Graphene has been widely utilized in optoelectronic applications due to its high carrier mobility, and extremely fast optical response. Microcavity-integrated graphene waveguide structure is one basic module of integrated photonic devices which can greatly improve the light-matter interaction strength. The enhanced optical absorption in the undoped graphene layer results from the light trapping and the corresponding long light-graphene interaction length. Tuning the Fermi energy level of the graphene layer enables the electro-optical modulation. We report the realization of reconfigurable electro-optical attenuator and switch with unity-order modulation depth in light reflection and transmission at near-infrared frequency. The transformation from a lossy absorber to a quasi-perfect transparent condition of the monolayer graphene by tuning the Fermi level leads to the unity-order tunability of the electro-optical attenuator and switch. We investigate theoretically and numerically the absorption properties of the designed microcavity-integrated graphene with respect to different graphene Fermi levels. Electro-optical attenuator with attenuating coefficient from 10% to 98.29% is fulfilled. On-off electro-optical switching with a switching contrast larger than 21 dB is demonstrated. Our approach provides the possibilities of graphene photonics applied in communications, and sensing. The weak optical absorption is detrimental to the realization of high-performance graphene based optoelectronic device6, where absorption up to 100% is desired8. Specifically, to develop optical devices such as photodetectors and optical antennas, high optical absorption in graphene is required to generate sufficient large photocurrents. Boosting the light-matter interaction strength in graphene is one important issue which needs to be addressed to take further advantage of graphene in optoelectronic devices. Microcavity structure has been demonstrated to possess excellent performance in confining light in the defect layer and hence greatly boosts light-matter interaction strength9. The light-matter interacting enhancement only occurs at the designed resonant wavelength, which makes it promising for the wavelength division multiplexing system10. For graphene, one important property is its optical absorption can be easily manipulated14. The conductivity of the graphene layer is highly sensitive to the Fermi level. By shifting the electronic Fermi level, one can controllably change graphene’s optical transitions to achieve unexpected tunable waveguide devices. The linear dispersion of the graphene Dirac fermions provides an ultra-wideband tunability by applying electrostatic field, magnetic field, or chemical doping.The intriguing optoelectronic and photonic properties of graphene has led to an increasing research interest in utilizing graphene for electro-optical applications. Generally, for monolayer graphene, the interaction strength with light is rather weak due to the inherent single atom thickness  of 1.2 eV and 1 eV have been experimentally achieved through electrostatic doping23 and chemical doping24. The refractive index of the surrounding media, between which graphene is located, also affect the graphene’s absorption characteristics. Normally, the absorption coefficient for the geometry with graphene acting as a conducting interface sandwiched between two dielectric media with refractive indices of n1 and n2, respectively, at different operating frequencies can be calculated utilizing the boundary conditions from Maxwell’s equations as25:ω is the angular frequency, Z0 = 120π Ohm is the free-space impedance and n1(ω) and n2(ω) are refractive indices of the surrounded dielectrics. The optical conductivity σ(ω) of graphene represents the electron transition and determines the electromagnetic wave absorption coefficient A(ω).The absorption coefficient of a monolayer graphene depends on its unique band structure and many other parameters including scattering rate, operating temperature, electron velocity, as well as electric and magnetic field bias3N4) and silica (SiO2) layers with thickness of 107 nm and 147 nm, and the bottom metallic mirror is set to be a 200 nm gold film (to make sure the reflection reaches to unity). The monolayer graphene is integrated into the defect region acting as an active electrochromic material. Note that, the selected materials of the Bragg mirror and the defect layer are non-absorbing at the resonant wavelength to provide high optical performance of the microcavity. The defect Si3N4 layer guarantees the maximum trapped electric field amplitude occurs right at the graphene sheet position. The thickness of the Si3N4 defect layer is set to be 104 nm.Microcavity offers a convenient method of actuation for electro-optical modulators: tunable optical characters of the integrated absorber layer can lead to the manipulation of the optical features of the incident light. One more attractive characteristic of the microcavity structure is its resonant response occurs only at wavelengths that are an integer fraction of the effective optical path length of the cavity. Great light confinement and enhancement in cavity provide strong light-matter interaction for optical routing with the need of relative lower input incident energy. Figure kB is the Boltzmann constant, T is the temperature, ω is the frequency, τ is the carrier relaxation time from the impurities, and EF is the Fermi level. The in-plane graphene permittivity is characterized as 29. The reflections of the Bragg mirror with different period numbers are depicted in Fig. 2/Si3N4 offers the Bragg mirror with reflection up to unity in a broad spectral range around 850 nm as the inset shows in Fig. The microcavity is considered to be critically coupled when the leakage rate of a guided resonant mode out of the Fabry–Pérot cavity is equal to the absorption rate in the graphene layer and all the incident light is absorbed correspondingly. We use finite different time domain (FDTD) method to simulate the optical behaviors of the Bragg mirror and the microcavity-integrated graphene waveguide to achieve critical coupling. Three-dimensional FDTD simulations are performed with periodic boundary conditions along the y and z directions and prefect matching layer (PML) condition along the x direction. During the simulation, the dynamical graphene optical conductivity is calculated using the random-phase approximation method as3N4 defect layer thickness. The varied cavity resonance and total absorption are due to the different interference strength of the counter-propagating incident and reflected waves at different defect layer thickness conditions. According to our calculation, the Q-factor (Q = λ/Δλ) of the resonant mode in the microcavity structure can reach as high as 328, which can be further enhanced by further increasing the defect layer thickness or selecting other defect material with higher refractive index . Owing to the broadband absorption of graphene, the concept of critical coupling at 850 nm also extends to other wavelengths by tuning the thicknesses of the quarter-wavelength alternating dielectric layer of the top Bragg mirror and the defect layer.Then we optimize the waveguide geometrical parameters for critical coupling through the transfer matrix method. The thickness of the bottom gold film mirror is firstly fixed to be 200 nm to ensure a perfect suppression on the incident light transmission. Next, the period number of the top Bragg mirror is optimized to cancel the reflection to obtain a unity-order absorption. Figure Continuous variable optical attenuators are key components of fiber optic communication networks and have been commonly used either to test power level margins or to control the intensity of one or more light wavelengths. One challenge within the current optical systems is to fabricate attenuator that is flexible, lightweight, reliable, and has a minimum amount of moving parts. Optical switching technology is intensively driven by the need to provide flexibility in optical network connectivity. In telecommunication, an optical switch is a device that enables signals in optical fibers or integrated optical circuits to be selectively switched from one circuit to another. We expand the concept of electro-optical attenuating and switching of graphene absorption by coupling to a high Q-factor microcavity. In the microcavity-integrated graphene waveguide, we assume no plasmonic response in the graphene layer. The light trapping and enhancement in the cavity region of the microcavity allows the strong interaction between the monolayer graphene and the incident light. The concept of the unity-order absorption model reminds us the tuning of absorption of the microcavtiy to achieve optical modulator by adjusting the absorption of the graphene layer. The critical coupling effect is robust, and the frequency where total absorption occurs can be tuned by adjusting either the waveguide geometric parameters or the material properties. The method through tuning the conductivity of the graphene to obtain absorption tunability by employing different graphene Fermi levels is much easier since graphene can be tuned from highly lossy to transparent or vice visa by tuning its Fermi level in visible and near-infrared region.In order to gradually tune the reflection to the greatest extend from zero to unity-order, the bottom mirror should be as close to perfect reflector as possible, since any transmission through it represents energy leakage, and this energy portion cannot be absorbed. With undoped monolayer graphene integrated into the cavity, full absorption of the normally incident light can always be obtained at resonant wavelength condition. Under this total absorption condition, when a proper doping condition applied on the graphene, the lossy graphene layer can be tuned to be transparent wherein the light can directly reach the bottom perfect mirror that reflects all of the incident light. Once we achieved de-critical coupling situation by tuning the Fermi level, we can obtain the reflection of the microcavity-integrated graphene waveguide larger than zero and even up to unity-order.EF = 0, graphene can absorb all of the incident electromagnetic waves corresponding to A ≈ 1, R ≈ 0 and T = 0 corresponding to a unity-order light confinement factor. When the graphene layer is highly doped (EF = 1 eV), it becomes nearly lossless, and the peak reflection reaches 90%. As shown in Fig. Figure EF = 1 eV to −0.48 dB at EF = 0 eV, resulting in an electro-optical switching contrast of 20.54 dB.The obtained switching effect is as following: for the microcavity-integrated graphene electro-optical switch, a connection is in the on state if the graphene is highly doped with essentially 10% loss in optical energy and 90% reflection. A connection is in the off state if essentially zero reflection emerges. The reflection coefficient is tunable from −21.02 dB at 2) and silicon nitride (Si3N4) layers with same geometrical parameters shown in Fig. 0.1Ga0.9As) and aluminum arsenide (AlAs) layers with thickness of 60 nm and 71 nm, respectively. The monolayer graphene is integrated into the defect Si3N4 region (same geometrical parameter shown in Fig. 0.1Ga0.9As offers the back Bragg mirror with reflection up to unity in a broad spectral range around 850 nm as well.The concept of the tunable reflection of the microcavity also applies to other types of resonators in which the incident field undergoes a significant enhancement in the cavity decorated with graphene. With two non-absorbing, nearly perfect reflecting Bragg mirrors as shown in Fig. Simulation results indicate that the implementation of the tunneling effect can be satisfied by setting the period numbers of the top and bottom Bragg mirrors of 8.5 and 19, respectively. Under complete transmission condition, the incident field has to be strongly amplified in the cavity. At resonance, the incident light traps inside the cavity and passes through the graphene layer multi-times similar to the above. Without graphene, the typical full width at half-maximum of the transmission spectrum is 3.3 nm and the Q-factor is 257.6. The transmission and reflection spectra of this Fabry–Pérot resonator at different Fermi levels are shown in Fig. In conclusion, we theoretically demonstrate the integration of a monolayer graphene layer into a microcavity to produce unity-order tunability in reflection, transmission and absorption of the normally incident light in the near-infrared domain by means of tunable critical coupling with the guided resonant mode. The modulation depths in light reflection and transmission in the two different microcavity-integrated graphene structures exceeding 90% and 75%, respectively, indicating small insertion losses. This attenuator/switch is configured to be compact, and lightweight while proving wavelength agility and tunability at chip-level, and can be used on platforms having limited size, weight, and power budgets. Due to the broadband tunable absorption of graphene, the proposed concept can extend to visible, mid-infrared and far-infrared domains by appropriately selecting the alternating dielectric layer thickness of the Bragg mirror and the thickness of the defect layer. Compared with the conventional electro-optical attenuators and switches, the microcavity-integrated graphene optical attenuator and switch provide a new path to develop graphene-based nano-scaled photonics with fast optical modulation speed, low electric power consumption, and easy integration with large-scale photonic array without complex packaging techniques, pointing to the applications in communications, sensing, security, and spectroscopy.


We hypothesized that ISP and SCPPopt can be predicted using clinical factors instead of ISP monitoring.We recently developed techniques to monitor intraspinal pressure (ISP) and spinal cord perfusion pressure (SCPP) from the injury site to compute the optimum SCPP (SCPPopt (SCPP that optimizes pressure reactivity). We studied how well 28 factors correlate with mean ISP or SCPPopt including 7 patient-related, 3 injury-related, 6 management-related, and 12 preoperative MRI-related factors.Sixty-four TSCI patients, grades A–C , were analyzed. For 24 h after surgery, we monitored ISP and SCPP and computed SCPPopt to be computed. Thirteen percentage, all AIS grade A or B, had no U-shaped sPRx versus SCPP curves. Thirty-six percentage (22/64) had U-shaped sPRx versus SCPP curves, but the SCPP did not reach the minimum of the curve, and thus, an exact SCPPopt could not be calculated. In total 5/28 factors were associated with lower ISP: older age, excess alcohol consumption, nonconus medullaris injury, expansion duroplasty, and less intraoperative bleeding. In a multivariate logistic regression model, these 5 factors predicted ISP as normal or high with 73% accuracy. Only 2/28 factors correlated with lower SCPPopt: higher mean ISP and conus medullaris injury. In an ordinal multivariate logistic regression model, these 2 factors predicted SCPPopt as low, medium–low, medium–high, or high with only 42% accuracy. No MRI factors correlated with ISP or SCPPopt.All patients underwent surgery to restore normal spinal alignment within 72 h of injury. Fifty-one percentage had U-shaped sPRx versus SCPP curves, thus allowing SCPPopt; thus, invasive monitoring remains the only way to estimate SCPPopt.Elevated ISP can be predicted by clinical factors. Modifiable factors that may lower ISP are: reducing surgical bleeding and performing expansion duroplasty. No factors accurately predict SCPPThe online version of this article (10.1007/s12028-018-0616-7) contains supplementary material, which is available to authorized users. The U-shaped curve is not always present and may vary throughout the period of monitoring; when computed in patients with head injury or spinal cord injury, a U-shaped sPRx versus SCPP relation is present approximately 50% of the time. ISP, SCPP, SCPPopt, and sPRx for TSCI are, respectively, analogous to intracranial pressure (ICP), cerebral perfusion pressure (CPP), optimum CPP (CPPopt), and cerebrovascular pressure reactivity (PRx) for traumatic brain injury (TBI) [Traumatic spinal cord injury (TSCI) is a catastrophic condition: Over a third of patients do not recover sensation or voluntary movement below the injury . No treary (TBI) .opt more often improve their AIS  grade than patients with SCPP very different from SCPPopt [opt could form the basis for individualizing the treatment of TSCI in a physiologically meaningful manner. When compared with the current guideline of maintaining MAP at 85–95 mmHg in all TSCI patients [opt, represents a paradigm shift. A universal MAP target is inadequate because TSCI patients have different ISPs and because the SCPPopt varies widely between patients [opt in each TSCI patient. The ability to estimate ISP and SCPPopt noninvasively would be a major advance by allowing doctors to calculate a target MAP for each TSCI patient without ISP monitoring.TSCI patients with mean SCPP ≈ SCPP SCPPopt . Thus, tpatients , the conpatients , 5, 8. TPatients were recruited as part of the Injured Spinal Cord Pressure Evaluation (ISCoPE) study . Approvals for ISCoPE were obtained from the St George’s, University of London Joint Research Office and the National Research Ethics Service London–St Giles Committee (No. 10/H0807/23).We include all (consecutive) TSCI patients recruited between October 2010 and December 2017. Inclusion criteria are: (1) severe TSCI defined as AIS grade A, B, or C; (2) age 18–70 years; (3) timing between TSCI and surgery within 72 h. Exclusion criteria are: (1) patient unable to consent; (2) other major comorbidities; (3) penetrating TSCI.®, Depuy Synthes, Leeds, UK) was placed intradurally on the surface of the injured cord at the site of maximal cord swelling. The dural opening was sutured and supplemented with fibrin glue . The ISP probe was connected to a Codman ICP box linked via a ML221 amplifier to a PowerLab running LabChart v.7.3.5 . Arterial blood pressure was recorded from a radial artery catheter connected to the Philips Intellivue MX800 bedside monitoring system , and in turn connected to the PowerLab system. ISP and arterial blood pressure signals were sampled at 1 kHz for 24 h after surgery. When the spinal cord is swollen and compressed against the dura, the subdural pressure  and intraparenchymal pressure at the injury site are the same. In this case, ISP is higher than cerebrospinal fluid (CSF) pressure above or below the injury site—details are given elsewhere [Surgical decompression and spinal instrumentation were performed based on patient requirements and surgeon preference. Some patients also had duroplasty as described . During lsewhere , 13–15.opt as the minimum of the curve. We used the ISP and MAP signals recorded over the 24 h after surgery to compute the average ISP, the average SCPP, as well as the overall SCPPopt. The ISP monitoring setup is illustrated in Fig. We processed signals using ICM + to compute SCPP (as ISP minus MAP) and sPRx (as the running correlation coefficient between ISP and MAP). Microsoft Excel was used to produce sPRx versus SCPP plots and estimate the SCPPAge,Sex,Smoking,Hypertension,Diabetes,History of excess alcohol consumption,Body mass index,Level of injury, i.e., cervical/thoracic/conus,AIS grade on admission,Primary survey MAP,Hours from injury to surgery,Duration of surgery,Intraoperative blood loss,Extent of decompression i.e., spinal alignment/spinal alignment + laminectomy/spinal alignment + laminectomy + duroplasty,Surgical approach, i.e., posterior/anterior + posterior,Mean MAP during surgery,Epidural hematoma,Intraparenchymal hematoma,Cord transection,Number of sagittal inter-vertebral levels with no CSF signal ,Injury level average spinal cord occupation rate: SCOR ,Brain and spinal injury center score BASIC ,Sagittal grade 1–4 ,Longitudinal extent of T2 signal abnormality ,Maximum spinal cord compression MSCC , 21,Maximum canal compromise MCC ,Average normal cord in injured cord ,Average % cord signal change at injured level . Detailed definitions of the 28 factors are given in the Supplement. Data regarding the 28 factors were collected without knowledge of the ISP, SCPP, and SCPPopt data.A total of 28 factors were collected for each patient as follows:opt between the factors. In the multivariate logistic regression analysis for ISP, we chose the best model based on likelihood by including factors with P < 0.1 and removing factors already in the model if P > 0.2 when a new factor is added. In the multivariate ordinal logistic regression analysis for SCPPopt, we chose a stepwise forward model based on the Wald criterion; the model enters factors with P < 0.1 and removes factors already in the model if P > 0.2 when a new factor is added. Correlations between two factors were quantified with the Spearman’s rank correlation coefficient “ρ”.Analyses were carried out with XLStat Biomed . For univariate analyses, we used Mann–Whitney U or Wilcoxon rank sum with post hoc Dunn to investigate differences in ISP or SCPPopt to be computed. Mean SCPPopt for all patients was 74 mmHg (range 48–103). Thirteen percentage (8/64), all AIS grade A or B, had no U-shaped sPRx versus SCPP curve for the first 24 h after surgery. The remaining 36% (22/64) patients appeared to have U-shaped sPRx versus SCPP curves, but the range of SCPPs did not reach the minimum, and thus, exact SCPPopt could not be calculated.Table P < 0.05) predictors of high ISP. Intraoperative blood loss was no longer significant because of collinearity with the level of injury (ρ = 0.59), i.e., more blood loss when operating lower down the spine.In univariate analysis, only 5/28 characteristics that were examined correlated with ISP. The 5 characteristics that were associated with higher mean ISP are no excess alcohol consumption, lower cord injury, not having a duroplasty, younger age, and more intraoperative blood loss , low–medium (60–70 mmHg), high–medium (70–80 mmHg), or high (> 80 mmHg). This allowed us to analyze 51 patients in total, by including not only the 34 patients who had exact SCPPopt, but also 8 patients with SCPPopt > 80 mmHg and 9 patients with SCPPopt < 60 mmHg. In univariate analysis, only 2/29 factors that were examined correlated with lower mean SCPPopt: higher mean 24-h ISP and lower spinal level of injury . Interestingly, again none of the 12 MRI factors correlated with mean SCPPopt. An ordinal logistic regression model based on these two factors could classify SCPPopt as low, low–medium, high–medium, or high with only 42% accuracy , the same trend may apply [opt by ISP monitoring.To conclude, our study supports the notion that ISP is determined by the size of the CSF space surrounding the injured cord. In other words, after TSCI, the cord swells and is compressed by the dura , thus, ftabolism . In TBI tabolism , althougay apply . To dateAt present there is no consensus about the correct paradigm for managing acute TSCI , 37, 38 Supplementary material 1 (PDF 1101 kb)Below is the link to the electronic supplementary material.


In humans, attentional biases have been shown to negative  and positive  stimuli. However, it is not clear whether these attentional biases reflect on stimulus driven, bottom up, or goal driven, top down, attentional processes. Here we show that, like humans, Japanese macaques show an attentional bias to snakes in a dot probe task (Experiment 1). Moreover, this attentional bias reflects on bottom up driven, preferential engagement of attention by snake images (Experiment 2a), a finding that was replicated in a study that used the same methodology in humans (Experiment 2b). These results are consistent with the notion that attentional bias to snakes reflects on an evolutionarily old, stimulus driven threat detection mechanism which is found in both species. Although snakes pose a lesser threat to the survival of modern humans, fear of snakes remains highly prevalent, even in locations where risk of fatal encounters with snakes is minimal. A large scale Swedish survey, for instance, revealed that 5.5% of a mainly urban sample reported levels of fear of snakes that are clinically relevant and which the respondents described as unjustified, uncontrollable, and impairing their everyday activities3. This rate seems remarkable as there is only one venomous snake native to Sweden (Vipera berus) and fatalities after bites are extremely rare4.The preferential detection of threats to survival is an important mechanism in the defensive armoury of any organism placed into a situation where the need for foraging competes with the risk of falling prey to a predator. However, threat detection mechanisms that are highly adaptive at one stage of evolutionary history may become vestigial and even maladaptive at a later one. In primates, the preferential attentional processing of snakes may provide an example for such a development. Snakes are a prime predator of non-human primates to the extent that the selection pressure exerted by snakes shaped the evolutionary development of the primate visual system5. Fear conditioning is assessed by pairing pictures of snakes or control pictures with aversive outcomes. In humans, preferential fear conditioning to snakes as indexed by physiological responses is evident in that it resists extinction, is selective to aversive learning, can be acquired within a single trial of training, and resists cognitive interventions such as instructions that further unconditional stimuli will not be forthcoming (for reviews see7). Similar evidence for preferential learning of a selective association between snakes and negative outcomes has been shown in laboratory reared rhesus monkeys (Macaca mulatta), even in absence of a direct experience of the negative outcome .The predisposition to detect and process images of snakes preferentially has been documented in humans and other primates in a number of different paradigms, most prominently in fear conditioning, visual search, and spatial attention tasks10 or non-threatening animals11. Here, participants are required to detect singleton pictures, e.g., a snake among flowers or a flower among snakes, as quickly as possible. Faster detection of snakes has been shown in human adults and children12 and in Japanese macaques (Macaca fuscata)14. Moreover, in human participants the faster detection of snakes is enhanced in participants who self-report high levels of fear of snakes15. This observation of individual differences renders it unlikely that preferential detection of snake pictures reflects on low level perceptual features of the stimulus materials used rather than on the content depicted. The evidence from visual search tasks has been criticised, however, as it is not clear whether faster detection of snake than of flower targets reflects on differences in target detection or on slower search through snake than through flower backgrounds11.Visual search has been employed as a paradigm to demonstrate preferential detection of snakes relative to non-threatening stimuli, such as flowers and mushrooms16. In this task, participants are simultaneously presented with two cues, e.g., pictures of a snake and a flower, for a short period of time and after their removal a probe, e.g., a dot, is presented in one of the cued locations. Participants are required to indicate the location or the identity of the probe as quickly as possible. Preferential allocation of attention to one of the images is indicated by faster responding to the probe that replaces this picture, e.g., attentional bias to snakes is evident if the probe replacing the snake is detected faster than the probe replacing the flower, whereas the inverse pattern of results is indicative of avoidance. The dot probe task has been applied to assess attentional bias not only in the context of animal phobias but anxiety disorders more broadly17 and more recently in contexts as diverse as addiction18, obesity and disordered eating19, and pain20. This broad interest reflects on the notion that attentional biases as reflected in the dot probe task may contribute to the development and maintenance of emotional disorders and that their reduction in attentional bias modification training may aid the treatment of these disorders21.A second task that is used, in particular in clinical research, to assess preferential allocation of spatial attention or biased attentional processing is the dot probe task22. Whether a similar attentional bias to snakes in the dot probe task can be observed in non-human primates is currently unclear23. This knowledge gap seems surprising given the importance attributed to attentional biases for the maintenance and mitigation of emotional disorders. Thus, it is important to determine whether such biases can be found in non-human primates or whether they reflect on an evolutionarily relatively recent phenomenon and are limited to Homo sapiens.Past research using the dot probe task in human participants has provided evidence that pictures of snakes (or spiders) bias attention and are preferentially attended to and that this bias is larger in participants who reported higher levels of fear of snakes24. However, the remaining two studies reported attentional biases to threatening facial expressions using either faces with neutral expressions25 or scrambled faces26 as controls. Moreover, the former study confirmed that this bias was selective to threatening facial expressions and not evident when positive expressions were presented together with the neutral controls. The prior work on attentional biases in non-human primates confirms the utility of the dot probe paradigm for their assessment. Thus, Experiment 1 will employ the dot probe paradigm to confirm that, like humans, non-human primates (Macaca fuscata) display an attentional bias to snake images.While there is no work on attentional bias to snakes in non-human primates, there is some prior work that assesses attentional biases to social stimuli, faces of conspecifics, in macaques. Contrary to predictions, one study failed to find evidence for larger allocation of attention to faces of infants over faces of adults24. Faster detection of a probe presented after a picture of a snake may reflect on preferential attentional engagement by snakes, i.e., the faster allocation of attention to snake images. Conversely, it may reflect on a delay of attentional disengagement from snake pictures after attention has been allocated to them. Whereas the former process would suggest a stimulus driven, bottom up attentional process the latter indicates the involvement of top down, goal directed attentional processes. Dissociating these two processes is important not only for a complete understanding of attentional biases, but also for the design of effective interventions as different interventions may differ in their effectiveness to modify them. It should be noted that some of the work on attentional biases in children12 can speak to this dissociation. However, past work in children has largely employed visual search tasks in which it is difficult to differentiate bottom-up and top-down attentional processes15.Although attentional biases in the dot probe task are a well-established phenomenon in humans, it is currently unclear which attentional processes underlie the biases observed27 suggested the inclusion of baseline trials on which two neutral images, e.g. two images depicting flowers, are presented as a means to dissociate preferential attentional engagement from delayed attentional disengagement in a dot probe task. In brief, preferential engagement is indicated if a probe in the same location as, say, a snake image  is found faster than a probe on a baseline trial whereas delayed disengagement is indicated if a probe presented in the location not occupied by the snake  is found slower than a probe on a baseline trial.Koster and colleagues28. However, more recent studies using a modified version of the dot probe task29 or a spatial cuing task30 also provide evidence for preferential attentional engagement by threatening visual stimuli. Experiment 2a will employ a design comprising snake-valid, snake-invalid, and baseline trials to assess whether the attentional bias in Macaca fuscata as shown in Experiment 1 is driven by preferential attentional engagement or delayed attentional disengagement. The study that documented attentional bias to snakes in humans22 did not employ an analysis that would permit the assessment of the underlying attentional processes, but reported performance on snake-valid and snake-invalid cued trials only . However, the study included baseline trials in which no animal pictures were presented. Thus, Experiment 2b will report a reanalysis of these data delineating whether the attentional bias to snake images is mediated by the same attentional processes in Homo sapiens and Macaca fuscata.Using pictures of mutilations and physical threat scenes, Koster and colleagues found that the attentional bias in their study was mainly driven by delayed disengagement of attention from threat, and a similar pattern emerged in a study that used words as stimulus materialsMacaca fuscata) display an attentional bias to pictures of snakes relative to pictures of flowers in a manner similar to that observed in humans22. Experiment 2a included baseline trials on which two flower pictures were shown as cues and was conducted to determine whether attentional bias to snakes in Japanese macaques reflects on preferential attentional engagement to or delayed disengagement from snakes. Experiment 2b reanalysed published data to assess whether the attentional bias in Macaca fuscata and Homo sapiens reflects on the same underlying attentional process.In summary, the current report is of two experiments conducted in non-human primates and a reanalysis of published data from humans. Experiment 1 was designed to determine whether Japanese macaques  aged 6, 7 and 8 years participated in the experiments. All were born in captivity in social groups at the Primate Research Institute of Kyoto University (Japan) and lived with their own mother and other group members in an enclosure that provides access to a large outside area and is located in a rural environment. Thus, prior encounters with snakes cannot be excluded completely, but can be assumed to be extremely unlikely. All experimental procedures were approved by the Ethics Committee of the Primate Research Institute of Kyoto University (#2015-012) and comply with the Guide for the Care and Use of Laboratory Primates .M = 20.2, SD = 4.92) provided informed consent and volunteered in exchange for course credit. The study had been approved by the University of Queensland ethics review board (B/14/Psych/ARCL/99).Sixty nine undergraduate students  placed in a sound-attenuating chamber. A 21.5-inch touch-sensitive LCD screen  was mounted on one side of the experimental box. A universal food dispenser  was placed in the experimental box to provide a piece of sweet potato, apple or raisins as a food reward. The food dispenser was controlled by computers with USB I/O interfaces . Stimulus presentation and food dispensation were controlled by a custom-written computer program.Participants were tested individually and performed the task on a personal computer running a custom written program. Stimuli were presented on a 17-inch colour monitor at a distance of 70 cm and participants provided responses via a button box.22. All pictures were sized to an area of 195 × 260 pixels. The average luminance was adjusted to equivalent values.The current study employed nine pictures of snakes and flowers used in prior research with human participants22.In addition to the pictures of snakes and flowers, participants also saw nine pictures each of spiders and mushrooms26. A fixation cross (size: 48 × 48 pixels) was shown in the screen center with the two pictures and the probe key following the procedure used in humans22. After the probe key was touched, the screen blacked out and the monkey was reinforced with a food reward accompanied by auditory feedback. The monkeys were required to touch the probe key within 1500 ms. After reinforcement, a 1000 ms inter-trial-interval (ITI) was inserted, and the next trial was started. If the monkey failed to touch the probe key within 1500 ms or touched the location opposite to the probe key, the screen blacked out and a buzzer sound was played. After an error, a 4000 ms ITI was inserted as negative feedback, and the next trial started delayed.Throughout the experiments, the monkeys were required to touch circles (size: 120-pixels in diameter) displayed one at a time on the touch screen. The events within a single trial and example pictures are illustrated in Fig. On snake-valid trials, the probe key appeared at the location previously occupied by the snake picture; on snake-invalid trials, the probe key appeared at the location previously occupied by the flower picture. Half of the trials in each session were snake-valid, whereas the other half were snake-invalid. Probe position (left or right) and SOA were counterbalanced across trials and each trial configuration was repeated 7 times. Consequently, each session comprised a total of 84 trials , presented in a randomized order. Each subject completed a total of 21 test sessions.27. Preferential attentional engagement by snakes is indicated by faster probe detection on snake-valid trials than on baseline trials. Delayed disengagement of attention from snakes is indicated by slower probe detection on snake-invalid than baseline trials. Each test session in Experiment 2a comprised 90 trials , and each subject completed 15 test sessions.Experiment 2a replicated the general procedure of Experiment 1, but 30 baseline trials on which two flower pictures were presented were randomly inserted among 30 snake-valid and 30 snake-invalid trials. The inclusion of baseline trials permits the assessment as to whether a response time difference between snake-valid and snake-invalid trials reflects on preferential engagement of attention by snakes or delayed disengagement of attention from snakes22). The probe followed the picture on the left for one exemplar of each combination and on right for the second. On each trial, a central fixation cross was presented alone for 500 ms, with two pictures centred in the left and right half of the screen for another 500 ms, and with a small white dot in the left or the right half of the screen for a further 500 ms. After the button corresponding to the probe location was pressed, an intertrial interval of 2000 ms commenced. Trials were presented in a random order without interruption. The task commenced with 10 practise trials and the instruction to work as quickly as possible while avoiding mistakes.In brief, participants were presented with a random sequence of 160 trials, five blocks of 32 trials each comprising two repetitions of the 16 possible combinations of the four picture categories  developed for R version 3.2.3. Significance levels were set at P < 0.05. We additionally subjected the results of the present study to mini meta-analyses31, using the R package, Metafor (https://cran.r-project.org/web/packages/metafor/metafor.pdf)32 to confirm the reliability of the attentional bias across our experimental manipulations. We calculated summary effect sizes of comparisons between conditions from individual results by using a random-effects model (restricted maximum likelihood estimation).Response times (RTs) were measured from the appearance of the probe key to the touch response. Trials on which the subject failed to touch the correct location, did not touch within 1500 ms or did not touch the screen precisely  were excluded from the analysis (6.9% in Experiment 1 and 9.7% in Experiment 2a). RTs within the experimental conditions were averaged for each session. To examine the presence of attentional biases, trial type  × target position  × SOA  mixed-effect model analyses of variance (ANOVAs) were conducted on RTs. Sessions were treated as random effects in the models. Post-hoc comparisons were conducted by calculating least square means and confidence intervals of differences between the conditions to be compared. The statistical analyses were performed separately for the three subjects, by using the lmerTest package with t-tests. All datasets are available through the OSF (https://osf.io/fvc9q).RTs from trials with errors (pressing the wrong button) and outliers reflecting RTs that deviated by more than three standard deviations from a participant’s mean were excluded from the analysis. Error rates were low (3–5%) and further analysis yielded no significant results. RTs from snake-valid cued trials, snake-invalid cued trials, and baseline trials, defined as trials on which a flower and a mushroom image were presented, were averaged and subjected to a within subject ANOVA conducted in SPSS. Follow-up analyses were performed with paired F = 20.80, p < 0.001, ηp2 = 0.160; Anoi: F = 27.10, p < 0.001, ηp2 = 0.200; Ringo: F = 23.10, p < 0.001, ηp2 = 0.170) and all subjects were faster if the probe was presented on the side of their preferred hand, right for Anoi  = 27.80, p < 0.001, ηp2 = 0.110) and Neru  = 76.90, p < 0.001, ηp2 = 0.260), and left for Ringo  = 82.90, p < 0.001, ηp2 = 0.270). As can be seen in Fig. F = 5.45, p = 0.020, ηp2 = 0.024) and Ringo  = 22.40, p < 0.001, ηp2 = 0.092), but not for Neru  = 3.83, p = 0.051, ηp2 = 0.017) for whom the analysis yielded a Trial type × SOA interaction  = 3.95, p = 0.021, ηp2 = 0.034). Follow up analyses confirmed that Neru was faster to detect the probe on snake-valid than on snake-invalid trials at a SOA of 300 ms (t(219.97) = 2.92, p = 0.004), but not at SOAs of 100 (t(219.97) = 1.49, p = 0.138) or 500 ms (t(219.97) = 1.01, p = 0.313). These results indicate that like humans Japanese macaques display an attentional bias to snakes. This bias was significant across all SOAs for two of the macaques tested whereas the third displayed the bias at a SOA of 300 ms only.For all three subjects, response time decreased with increasing SOA  = 34.20, p < 0.001, ηp2 = 0.220; Anoi: F = 51.20, p < 0.001, ηp2 = 0.300; Ringo: F = 16.40, p < 0.001, ηp2 = 0.120), and all subjects were faster if the probe was presented on the side of their preferred hand, right for Anoi  = 79.80, p < 0.001, ηp2 = 0.250) and Neru  = 359.50, p < 0.001, ηp2 = 0.600), and left for Ringo  = 248.10, p < 0.001, ηp2 = 0.510). The probe detection times in the baseline, snake-valid, and snake-invalid trials of Experiment 2a are shown in the left panel of Fig. F = 3.09, p = 0.047, ηp2 = 0.025; Anoi, F = 4.49, p = 0.012, ηp2 = 0.036; Ringo, F = 5.56, p = 0.004, ηp2 = 0.045), but the overall pattern differed slightly. Subsequent post-hoc comparisons revealed faster probe detection on snake-valid than on snake-invalid or baseline trials for Neru  = 2.25, p = 0.03; baseline: t(238) = 2.04, p = 0.04) and Anoi  = 2.81, p = 0.005; baseline: t(237.9) = 2.30, p = 0.022). Ringo detected the probe faster on snake-valid than on snake-invalid trials, t(238) = 3.32, p = 0.001, with only a marginal difference between snake-valid and baseline trials, t(238) = 1.94, p = 0.054. There were no significant differences in probe detection time between snake-invalid and baseline trials for any of the three subjects (Neru: t(238) = −0.21, p = 0.830; Anoi: t(237.9) = −0.51, p = 0.610; Ringo: t(238) = −1.38, p = 0.170). This pattern of results seems to show that attentional bias to pictures of snakes in Japanese macaques reflects stimulus driven preferential engagement of attention.As in Experiment 1, probe detection times decreased with increasing SOAs in all subjects  = 5.42, p = 0.007, ηp2 = 0.139, with faster probe detection on snake-valid than on baseline, t(68) = 2.79, p = 0.007, and on snake-invalid trials, t(68) = 3.15, p = 0.002, but no difference between baseline and snake-invalid trials, t(68) < 1. Thus, the attentional bias to snake pictures in humans, like in Japanese macaques, reflects on preferential engagement of attention.As shown in the right panel of Fig. p = 0.033; 300 ms: MD = −19.38, CI = , p < 0.001; 500 ms: MD = −15.34, CI = , p = 0.012). These results support the conclusion of faster RTs on snake-valid trials across SOAs in all monkeys.The results of the current series of experiments seem to reflect a common trend of an attentional bias to snake images between species. However, the results of Experiments 1 and 2a for monkeys were sometimes weak and inconsistent. Unlike the other two monkeys, Neru showed a reduced RT on snake-valid trials only in one SOA condition in Experiment 1. On the other hand, comparisons between trial types in Experiment 2a revealed unique results for Ringo. To confirm the reliability of the attentional bias towards snake images in monkeys, we performed a mini meta-analysis across individual results. We firstly reassessed the bias towards snake images at each SOA by integrating individual results from Experiment 1 and 2a (N = 6). We calculated summary effect sizes for the comparison between snake-valid and snake-invalid trials at each SOA. Figure p = 0.033; MD = −17.68, CI = , p = 0.004, respectively) while no difference emerged between baseline and snake-invalid conditions . Moreover, Experiment 2a indicates that this bias reflects on preferential engagement of attention by snakes. In Experiment 1, all subjects were faster to detect probes following a snake picture than a picture depicting flowers, although for one subject this difference was significant only at one SOA. Experiment 2a, replicated this result for all subject across all SOAs. Moreover, the inclusion of baseline trials27 in Experiment 2a permits the delineation of the attentional process that underlies this bias. Rather than delayed disengagement of attention, the faster detection of probes following snake pictures reflects on the preferential engagement of attention by snakes. A reanalysis of existing data in humans22 based on a subset of trials that matched the trial types used in Experiment 2a confirmed that the same process underlies attentional bias for snakes in humans. Humans, like macaques, were faster to detect probes on snake-valid cued trials than on baseline trials or snake-invalid cued trials with no difference between snake-invalid cued trials and baseline trials. Rather than reflecting on delayed attentional disengagement, the attentional bias seen in humans is driven by preferential engagement of attention by snakes.Across two experiments which comprised three independent replications each, the current manuscript documents an attentional bias to snake images in Japanese macaques (2. It is in contrast with past findings from human research28 which suggest that attentional bias to stimuli depicting physical threat, pictures of mutilations or physical attack, or to negative words is driven by delayed disengagement of attention. Taken together the current results contribute to the increasing body of evidence that attentional biases may emerge on different levels of information processing which may require different approaches if they are to be the target of clinical interventions. This is well illustrated by the apparent failure of attentional bias modification training in cases of spider fear21.The current report indicates that, like humans, Japanese macaques show an attentional bias to images of snakes in the dot probe task. Moreover, it confirms across species that this attentional bias to snakes reflects on the preferential engagement of attention by snakes. This finding is consistent with the view that preferential attention to potential predators such as snakes is stimulus driven in a bottom up manner and may reflect on a perceptual system shaped by evolution that is highly sensitive to their detection33, most studies found similar results for both target animals with faster detection in visual search that is enhanced in persons fearful of either snakes or spiders15 or faster detection of probes cued by snakes or spiders22. However, a recent visual search study in Japanese macaques found faster detection of snakes but not of spiders14 and a human study employing a visual cuing paradigm found evidence for preferential bottom up attentional processing of spiders only if they were goal relevant30. This pattern of results suggests that more research is needed across experimental paradigms and participant species to gain a more complete understanding of the processes reflected in attentional biases to threatening animals.The current results also raise questions as to the boundary conditions for the bottom up driven attentional bias observed across species in the current experiments. Past research in humans on attentional bias to threatening animals has frequently employed pictures of snakes and spiders as stimulus materials. Although not universally so2 and found not only in non-human primates that share our evolutionary ancestors6. It enhances our understanding as to the processes that mediate attentional biases and suggests that attentional bias training to reduce fear of snakes has to target bottom up, stimulus driven attentional processes.The current study provides converging evidence across two primate species for attentional biases to snakes in a spatial attention task. Moreover, in both species, the bias reflects on stimulus driven preferential attention to snakes rather than on delayed disengagement from snakes. This observation is consistent with the notion that attentional biases to snakes reflect on threat detection mechanisms that are evolutionarily old


This article contains quality of life data experienced by individuals before and after implantation of a press-fit or screw-type osseointegrated fixation when fitted with conventional socket-suspended and bone-anchored limb prosthesis, respectively. This specifically-designed survey was developed and administered by Queensland Artificial Limb Services (QALS), an Australian State government organization. It was an integrated part of QALS′ continuous quality improvement procedure for assessing the provision of bone-anchored prosthesis. A total of 12 out of the 65 consumers completed to the survey, giving a return rate of 18%. This benchmark information can contribute to inform the design of (A) other patients' experience surveys including those built-in governmental continuous quality improvement procedure as well as (B) clinical trials looking at the overall effects of surgical implantation of ossoeintegrated fixation on patients' quality of life. Online repository contains the files:  This cohort represented circa 16% and 7% of existing population estimated at 400 in Australia and 950 worldwide, respectively 6.1.2This specifically-designed survey data on the quality of life was administered by Queensland Artificial Limb Services (QALS), an Australian State government organization, as an integrated part of its continuous quality improvement procedure for assessing the provision of bone-anchored prosthesis •7 (28%) questions about “Osseointegration Surgery Details” ,•5 (20%) questions about “Pre-Osseointegration Surgery” ,•13 (52%) questions about “Post-Surgery Osseointegration” .First, participants were required to indicate their name, address, date of birth and email. Then, participants answered 25 questions organized around the three following sections:The 65 eligible consumers were asked to participate in this study over the phone by a QALS' agent. Consumers could choose if they preferred receiving the survey by email or by post with pre-paid return envelope.6.1.3•○4 (16%) questions focusing on efficacy, particularly the level of function ,○1 (4%) question focusing on experience, particularly the level of satisfaction ,○3 (12%) questions focusing on knowledge of the osseointegration treatment , particularly the motivation for considering the procedure and the sources of information considered where promotional information included TV and social media.7 (28%) questions providing baseline outcomes that related to the quality of life of QALS′ consumers fitted with socket-suspended prosthesis before implantation of osseointegrated fixation including:•○2 (8%) questions focusing on surgery , particularly the time of the surgery and the level of satisfaction with the procedure,○2 (8%) questions focusing on safety or harms , particularly the occurrence of infection 17 (68%) questions assessing the quality of life of QALS′ consumers fitted with bone-anchored prosthesis after implantation of osseointegrated fixation including:•○4 (16%) questions focusing on efficacy, particularly the level of function ,○1 (4%) question focusing on experience, particularly the level of satisfaction ,○3 (12%) questions focusing on knowledge of the osseointegration treatment , particularly the motivation for considering the procedure and the sources of information considered where promotional information included TV and social media.7 (28%) questions providing baseline outcomes that related to the quality of life of QALS′ consumers fitted with socket-suspended prosthesis before implantation of osseointegrated fixation including:•○2 (8%) questions focusing on surgery , particularly the time of the surgery and the level of satisfaction with the procedure,○2 (8%) questions focusing on safety or harms , particularly the occurrence of infection ○6 (24%) questions focusing on efficacy or benefits , particularly the level of function ○6 (24%) questions focusing on overall experience , particularly the limitations and level of satisfaction.17 (68%) questions assessing the quality of life of QALS′ consumers fitted with bone-anchored prosthesis after implantation of osseointegrated fixation including:•1 (4%) general comments provided by consumers focusing on limitation of their observation time as well recommendations, benefits and shortcomings of the treatment .Analysis of the survey data consisted in extracting information for:Answers to the 10 (40%) dichotomous questions  were expressed in percentage of individual responses .Answers to the 3 (12%) Likert-type scale questions were expressed as percentage of participants in each of the 10 levels between 0 for “not satisfied” and 10 for “very satisfied” .○6 (24%) questions focusing on overall experience , particularly the limitations and level of satisfaction.•1 (4%) general comments provided by consumers focusing on limitation of their observation time as well recommendations, benefits and shortcomings of the treatment .Answers to the 12 (48%) open-ended questions were coded accordingly to the recurrence of themes in the replies .Answers to the 10 (40%) dichotomous questions  were expressed in percentage of individual responses .Answers to the 3 (12%) Likert-type scale questions were expressed as percentage of participants in each of the 10 levels between 0 for “not satisfied” and 10 for “very satisfied” .Answers to the 12 (48%) open-ended questions were coded accordingly to the recurrence of themes in the replies .7Only aggregated data was presented in this study. Exploration of more detailed analysis revealed that proportionate and disproportionate stratification sampling were unattainable given the diversity of case-mix and the small number of respondents.


Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) images of graphene reveal either a triangular or honeycomb pattern at the atomic scale depending on the imaging parameters. The triangular patterns at the atomic scale are particularly difficult to interpret, as the maxima in the images could be every other carbon atom in the six-fold hexagonal array or even a hollow site. Carbon sites exhibit an inequivalent electronic structure in HOPG or multilayer graphene due to the presence of a carbon atom or a hollow site underneath. In this work, we report small-amplitude, simultaneous STM/AFM imaging using a metallic (tungsten) tip, of the graphene surface as-grown by chemical vapor deposition (CVD) on Cu foils. Truly simultaneous operation is possible only with the use of small oscillation amplitudes. Under a typical STM imaging regime the force interaction is found to be repulsive. Force–distance spectroscopy revealed a maximum attractive force of about 7 nN between the tip and carbon/hollow sites. We obtained different contrast between force and STM topography images for atomic features. A honeycomb pattern showing all six carbon atoms is revealed in AFM images. In one contrast type, simultaneously acquired STM topography revealed hollow sites to be brighter. In another, a triangular array with maxima located in between the two carbon atoms was acquired in STM topography. Graphene has been widely studied because of its potential use in future nanoelectronics, as it provides unprecedented mobility of charge carriers at room temperature . MoreoveNowadays, a variety of methods are used to prepare graphene. Mechanical exfoliation of graphite facilitates obtaining micrometer-scale graphene layers on amorphous substrates such as silicon oxide . GraphenTheoretically, current in STM and attractive force in AFM have a similar origin . HoweverDuring the past decade, STM and AFM studies of graphene have been shown to yield honeycomb or triangular patterns due to different experimental parameters or sample preparation –10. Alsoa atoms. The other three carbon atoms, which are denoted as b atoms, are placed right above the hollow sites of the underlying graphene layer. This results in the two types of surface atoms to be electronically inequivalent. Since, b atoms have a greater contribution to the density of states close to Fermi energy compared to a atoms, they are imaged as bright spots at low bias voltages based on the STM investigations. These b atoms form a new larger triangular structure in STM images . Although most of the STM studies on graphene at low bias voltages show triangular patterns where b atoms were indicated as bright spots, some other experiments at closer tip–sample separations show triangular patterns where bright spots were identified as hollow sites. This is interpreted as a consequence of current saturation in the near-contact regime [In most of the STM investigations on graphene, atomic triangular patterns were reported for a broad range of bias voltages –21. In at regime –26.There is a variety of substrate materials which graphene is grown on. Graphene–metal bonds could be divided into two main groups, i.e., “strongly bonded” and “weakly bonded”. Graphene–Ni, graphene–Co and graphene–Rh are classified as strongly bonded and others such as graphene–Cu, graphene–Au and graphene–Ir are classified as weakly bonded. Moreover, graphene–metal interaction can result in a lattice-matched  or lattice-mismatched configuration  .Material and termination of the apex of the tip play an important role in STM and AFM results as well. Due to the strong interaction between metal tip and carbon atoms, atomic resolution can be obtained in both attractive and repulsive regimes, but with inverted contrast . Some FMIn this work, using a simultaneous STM/AFM working with sub-angstrom oscillation amplitudes we intended to gain insight on relative contrast mechanisms in STM and AFM, on a graphene surface. In the past, we used this small-amplitude STM/AFM technique in order to investigate surfaces such as Si(100) , Cu(100)−4 Å/√Hz is capable of measuring tunnel current, force, force gradient, tunnel barrier height and energy loss [−10 mbar is achievable by baking out the chamber.Our setup is a commercial STM/AFM operated in ultrahigh vacuum (UHV) that was modified and improved by the implementation of a Fabry–Pérot fiber interferometer in order to achieve high sensitivity in detecting lever deflection and measuring the oscillation amplitude, which in turn allows us to conduct simultaneous STM/AFM measurements. This system with a sensitivity of 2·10rgy loss . The UHVThe oscillation amplitude of the cantilever plays a major role for the actual simultaneous measurement of forces and tunneling current. Large lever oscillation amplitudes offer only a limited range in which tip is in the tunneling cycle. Using very small (sub-angstrom) lever oscillation amplitudes, the tip is kept in the tunneling range during the entire cycle. Consequently, while the constant tunnel current is used as feedback loop, the use of very small oscillation amplitudes ensures simultaneous STM/AFM operation as close as possible to the actual STM mode ,33. The F = klever·(A0 – A), where klever is the lever stiffness, A0 the free oscillation amplitude, i.e., far from the surface, and A is the measured amplitude during tip–surface interactions [With the use of sub-angstrom oscillation amplitudes, far from resonance, the tip–sample force corrugation in the images obtained at very close separations, can be calculated using ractions .2 + Ar atmosphere up to 950 °C. Upon reaching the process temperature, the Ar flow was stopped and the H2 flow was reduced while CH4 was let in to the quartz tube as the carbon source. As-grown samples, as well as graphene crsytals transferred on to dielectric substrates were investigated by optical microscopy and scanning electron microscopy (SEM). Raman spectra taken on several samples showed the presence of dominantly single-layer graphene [Graphene layers were grown on Cu foils using chemical vapor deposition (CVD) . A custographene .We used a custom-made tungsten tip–cantilever probe  the stifF–d) measurement presented below. Ondracek et al. [In the force image, brighter shading corresponds to more positive values. This means that C atoms reveal a more repulsive force compared to the hollow sites. This makes sense if the imaging regime is beyond the force minimum . This will be supported by the force–distance  and constant-height (CH) scans. The force corrugation contrast between carbon and hollow sites is found to be about 0.1 nN for both CC and CH modes. Thus, as far as the force is concerned the tip trajectory in CC mode does not have a considerable influence on the measurement of the oscillation amplitude. A similar behavior was observed in a previous work on Si(111) using the same small amplitude STM/AFM technique .F–d) spectroscopy measurements. At a certain point on the sample, by changing the distance between the surface and the tip, we simultaneously measure the force as well as tunnel current. It is difficult to do site-specific spectroscopy at room temperature due to thermal drift. Our goal was to carry out spectroscopy on a carbon and a hollow site. We imaged the surface for a long while until the thermal drift was minimized. Then by moving the tip to targeted lateral positions (carbon and hollow sites) we obtained several F–d curves. The curves revealed two distinct features particularly regarding the onset positions of tunnel current and force interaction, as shown in F–d measurements at a particular tunnel-current set point, the curves obtained on the hollow site are displaced by 2 Å, obtained from the STM corrugation in the image before, to account for the shift between the hollow and carbon site measurements  plays an important role in the relative contrast of different sites on the graphene surface. In order to shed light on the contrast differences in imaging we have also conducted force–distance (urements . Based oAnother set of simultaneous scans obtained using the same W cantilever at a positive sample bias of +0.5 V is shown in a-type and b-type carbon atoms in HOPG is predicted to be possible in the work by Teobaldi and co-workers [a-type and b-type carbon atoms at bias voltages between 0.3 and 0.7 V. In the upper part of the scans, we see a qualitative behavior similar to the lower part in both STM and force. However, the line profiles show a different quantitative behavior in force scan. Now the two C atoms reveal the same force value as can be clearly seen in the line profile. It is well known in scanning probe microscopy that such contrast changes may occur due to a change in the atomic structure of the tip apex. The fact that there is no sign of an abrupt change in the scans in both channels and the gradual increase in height in STM scan, which amounts up to 1 Å, may have suggested a real height change due to buckling/twisting of the topmost layer or change in LDOS between the two regions. The change in force contrast accompanied by a slight change in STM topography could suggest a change in alignment of the topmost layer with the underlying graphene layer or the substrate. However, we cannot rule out the possibility of a tip change occurring smoothly during several scan lines, which would result in the changes observed in force and STM images, both qualitatively and quantitatively.In the lower part of the scan, the line profile of the force clearly distinguishes the two C atoms and the hollow sites, one of the C atoms revealing a considerably larger force than the other. Comparing the STM line scan with the force, we see that the bright spots in the triangular pattern of STM topography corresponds to the middle of the two C atoms. The observation of STM topography maxima between -workers . Upon oba-type or b-type carbon atoms or hollow sites. The triangular patterns in STM topography in this work resulted in maxima in between the two C atoms, which is supported by theoretical calculations. Such an observation would not be possible without simultaneous acquisition of tunnel current and force interaction. Under the typical STM imaging conditions of graphene, the tip–sample interaction force is in repulsive regime. This behavior, which has been observed ever since the very early STM results of the HOPG surface, is shown to be the case in graphene surface as well. Hence atomic relaxations might be quite influential in STM imaging of graphene. The contrast mechanisms could be understood using simultaneous STM/AFM. Truly simultaneous operation is possible only with the use of sub-angstrom oscillation amplitudes.We investigated graphene grown on Cu foils using simultaneous STM/AFM with a metallic cantilever oscillated with sub-angstrom amplitudes. Different relative contrasts between STM and force are obtained. Both honeycomb and triangular patterns are observed in STM images. The maxima in the triangular patterns in STM images of HOPG and graphene presented in the literature have been assigned to either


Dear Editor,The study by Kurtz et al.  shed ligThe mixed methods study highlighted that students found writing questions a beneficial tool . HoweverMaximum benefit from these devised questions would require questions to cover universally challenging themes identified by students. As question authors have researched their difficult topic in detail, relevant information found should be included alongside answers. Students benefit from collaborative reviews  so may aIn addition to concerns about time spent writing questions, there may be limitations with different question styles. Imperial College School of Medicine regularly tests students with Single Best Answer questions (SBAs) rather than MCQs. SBAs are an excellent tool to consider similar differentials and focus on the most likely and ‘best’ option. However, developing these questions is difficult and students may have insufficient knowledge to consider which option is first-line and appropriate plausible detractors . HoweverTo conclude, as highlighted by Kurtz et al , creatin


Keloids develop due to hyperactivity of keloid fibroblast (KF) in proliferation, migration, and collagen deposition along with low rates of collagen degradation. These are a result of the Wnt/β catenin signaling pathways under stimulation of TGF-β. 5α-oleandrin can suppress Wnt-targeted genes of osteosarcoma cells. We aimed to evaluate the anti-fibrotic effects of 5α-oleandrin on KF activities.We collected the core of keloid materials from six patients who underwent keloid debulking surgery. Passage 4 of KF cells were then treated with mitomycin-C, 5α-oleandrin, and dilution medium as the negative control. To determine the effective dose of 5α-oleandrin, we diluted 5α-oleandrin into various concentrations. The incubation periods were 24 h, 48 h, and 72 h. The anti-proliferation and anti-fibrotic properties were measured using standard assay.p ≤ 0.05) compared to the non-treated group. Antifibrotic activities of 5α-oleandrin in cellular proliferation and collagen deposition were better than mitomycin-C.Both the mitomycin-C and 5α-oleandrin treated groups indicated decrease in proliferation index , collagen deposition index , and migration capacity . These were significant changes (The 5α-oleandrin has good antifibrotic effect in keloid fibroblast activities. Keloids are a fibroproliferative benign tumor that only affects human skin with characteristic overgrowth of scar tissues that exceeds the original wound size . This chEach transforming growth factor beta (TGF-β) subclass has a different role in wound healing, and transforming growth factor beta 1 (TGF-β1) is well known as an important growth factor in keloid formation . This gr32H48O9) isolated from Nerium indicum Mill. This material can significantly inhibit cellular proliferation and cellular invasion by suppressing Wnt-targeted genes of osteosarcoma cells [− 6 mM, but it is less cytotoxic against normal human cells [Nerium oleander taken orally for 21–28 days is well tolerated in heavily pretreated patients with advanced solid tumors [Recently, many natural products are tested for anticancer properties including oleandrin .3 core of each material was thinly sliced into 0.2–0.3 cm3 pieces and cultured via an explant method in Dulbecco’s Modified Eagle’s Medium  containing 10% fetal bovine serum  and 1% penicillin/streptomycin  at 37 °C and 5% CO2. The spindle-shaped cells that grew out from the explants then were sub-cultured until passage-4.We collected the core of keloid materials from six patients who underwent keloid debulking surgery after completing informed written consent forms. The age range of the patients was 18–23 years old. A 2 cm.Passage 4 of KF cells from each patient were then treated with mitomycin-C, 5α-oleandrin, and dilution medium as the negative control. We used 5α-oleandrin purchased from the Department of Pharmacology and Therapy, Faculty of Medicine, our university as the experimental groups; mitomycin-C  was the positive control. Both materials were diluted in DMEM containing 10% fetal bovine serum plus 1% penicillin/streptomycin in various concentrations. We used the lowest effective dose of mitomycin-C (30 μM) as previously reported by Dachlan et al.  as the p/ OD of paired non-treated group) × 100%.The anti-proliferation property was measured by measuring cellular viabilities using MTT -2,5-diphenyltetrazolium bromide) purchased from MP Biomedicals, France. The resulting optical density (OD) of the formazan product produced by the MTT and living cells was measured at 570 nm. The OD of the non-treated group was defined as 100% proliferation, and the proliferation index of various treated groups was counted as:  assay based on the method of Taskiran et al. . The OD The anti-fibrotic property was also determined via a cellular migration assay based on Liang et al. . Brieflyp < 0.05 was considered as significant level.All data were presented as a mean ± standard error. We used Analysis of Variance (ANOVA) followed by Fisher’s Least Significant Difference (LSD) to analyze data with normal distribution. For data with abnormal distribution, we used the Friedman followed with Wilcoxon rank sign test. p ≤ 0.05) compared to the non-treated group. The comparison between mitomycin C and 5α-oleandrin proliferation indices, collagen deposition, and migration capacity are detailed below.Both the mitomycin-C treated group and the 5α-oleandrin-treated group indicated a decrease in proliferation , collagen deposition index , and migration capacity . This was a significant change  as shown in Fig. The activity of keloid fibroblast migration after 72 h was higher in the administration of 5α-oleandrin than that of mitomycin C  or 5-ethynyl-2′-deoxyuridine (EdU-)incorporation assay, and the cell death measurement test, such as TUNEL or anti-caspase-3 staining, becoming a limitation of our study.5α-oleandrin has good anti-fibrotic effect. Further study is still necessary to reveal more specific manner of this substance as anti-proliferation agent. BrdU- or EdU- incorporation assay are suggested method to examine cells proliferation. Either BrdU and EdU assay are sensitive method but special precautions have to be noted due to their toxic, potential mutagenic, and/or teratogenic effects.


Sarcoidosis is a non-necrotizing granulomatous inflammatory syndrome with multisystemic manifestations. We performed a systematic review of sarcoidosis in the pediatric population with particular emphases on early onset sarcoidosis, high-risk sarcoidosis, and newly reported or unusual sarcoid-related diseases. Blau Syndrome and early onset sarcoidosis/ BS-EOS are seen in children younger than five years old presenting with extra-thoracic manifestations but usually without lymphadenopathy and/or pulmonary involvement. The prevalence of high-risk sarcoidosis is very low in children and is further limited by the difficulty of diagnosis in symptomatic children and underdiagnosis in subclinical or asymptomatic patients. Reports of sarcoidal syndromes in users of E-cigarette/marijuana/other flavorings and their induction in cancer immunotherapies are of interests and may be challenging to differentiate from metastatic malignancy. The diagnostic considerations in pediatric sarcoidosis are to support a compatible clinicoradiographic presentation and the pathologic findings of non-necrotizing granulomas by ruling out granulomas of infective etiology. There is no absolutely reliable diagnostic test for sarcoidosis at present. The use of endoscopic bronchial ultrasound (EBUS) and transbronchial fine needle aspiration (TBNA) sampling of intrathoracic lymph nodes and lung, and for superficially accessible lesions, with cytopathological assessment and pathological confirmations provide fair diagnostic yield and excellent patient safety profile in children. Sarcoidosis is a multisystemic syndrome with a highly variable clinical course and diverse disease manifestations . The incSarcoidosis is an ever-evolving process. The clinical phenotypes range from single-organ, self-limited, asymptomatic disease to multi-organ involvement with high-risk manifestations . Hilar lThe diagnosis of sarcoidosis is relatively uncommon in children ,11,12,13We performed a systematic narrative review on sarcoidosis with particular emphases on early onset sarcoidosis, high-risk sarcoidosis, and newly reported or unusual sarcoid-related diseases in the pediatric population. We searched PubMed, Scopus, Google Scholars, and Cochrane Database of Systematic Reviews, using the following terms: sarcoidosis, pediatric, juvenile, children; high-risk sarcoidosis; pulmonary sarcoidosis; treatment-resistant sarcoidosis; cardiac sarcoid; and neurosarcoidosis. We also searched references from the appropriate reviews and case reports.The true incidence and prevalence of sarcoidosis in children is unknown as the disease is much less common in children than in adults . It is dIn younger children, the majority of cases of EOS seen in children younger than five years old uniquely presents with a clinical triad of uveitis, arthritis, and skin rash . In 1985CARD15/NOD2 encodes a multidomain cytosolic protein and is expressed primarily in the cytosol of antigen-presenting cells . StimulaApproximately 25% of affected individuals with sarcoidosis develop chronic or progressive disease . ManifesRecent progress in cell-mediated immunity and granuloma formation has advanced our understanding of the development of sarcoidosis ,35. MacrCardiac sarcoidosis (CS) is a rare but potentially fatal condition . ClinicaNeurosarcoidosis occurs in fewer than 5% of adult with systemic sarcoid with isolated neurosarcoidosis being more rare , and to In contrast to the chronic progressive disease with organ dysfunction in high-risk sarcoidosis, two acute sarcoidosis syndromes are of relatively benign clinical outcome. Lofgren syndrome is characterized by fever, bilateral hilar lymphadenopathy, erythema nodosum, and arthralgia, typically in young women, primarily Caucasian. Prognosis is excellent with complete resolution of the disease in 90% of the patients within two years ,49,50. HPathology images of the spectrum of pediatric sarcoidosis involving different organs . Recent case reports of sarcoidosis developing after antigen exposure to inhalation or in immune-therapy are of interests. The popularity of electronic cigarettes (E-cig) has recently been increasing among adolescents and young adults ,55,56. EThere is no absolutely reliable diagnostic test for sarcoidosis . A numbeIn the spectrum of pediatric sarcoidosis, depending on the initial clinical presentation and subsequent investigations including various diagnostic imaging modalities, sarcoidosis is a diagnosis of exclusion, with ruling out granulomatous infections, in particular by Mycobacterial and fungal organisms ,52. A hiCases of high-risk sarcoidosis in children with the involvement of treatment-resistant pulmonary disease, cardiac sarcoidosis, neurosarcoidosis, and multi-organ disease and the recent reports of E-cigarettes and immunotherapy-related sarcoidosis are uncommon. The lung is the most frequent site for biopsy confirmation, followed by skin, peripheral lymph nodes, and liver ,72. The Since the initial clinical description by Jonathan Hutchinson  in 1877,Lofgren syndrome patients develop acute sarcoidosis, and show reduced frequency of lung-resident regulatory T cells (T-reg). The T-reg, however, super-synthesizes interleukin IL10, as supported by the detection of increased BAL fluid IL10 concentration , thus, cWe summarize the clinicopathologic spectrum of pediatric sarcoidosis and the diagnostic considerations in


Hyperactivation of Wnt/β-catenin target gene expression is a hallmark of colorectal cancer (CRC) development. We identified L1-CAM (L1) and Nr-CAM, members of the immunoglobulin family of nerve cell adhesion receptors, as target genes of the Wnt/β-catenin pathway in CRC cells. L1 overexpression in CRC cells enhances their motile and tumorigenic capacity and promotes liver metastasis. L1 is often localized at the invasive edge of CRC tissue. Using gene arrays and proteomic analyses we identified downstream signaling pathways and targets of L1-mediated signaling. Here, we found that the expression of interferon-stimulated gene 15 (ISG15) that operates much like ubiquitin (is conjugated to proteins by ISGylation), is elevated in the conditioned medium and in CRC cells overexpressing L1. Suppression of endogenous ISG15 levels in L1-expressing cells blocked the increased proliferative, motile, tumorigenic and liver metastatic capacities of CRC cells. ISG15 overexpression, on its own, could enhance these properties in CRC cells, but only to a much lower extent compared to L1. We show that NF-κB signaling is involved in the L1-mediated increase in ISG15, since blocking the NF-κB pathway abolished the induction of ISG15 by L1. Point mutations in the L1 ectodomain that interfere with its binding to L1 ligands, also inhibited the increase in ISG15. We detected high levels of ISG15 in human CRC tissue cells and in the adjacent stroma, but not in the normal mucosa. The results suggest that ISG15 is involved in L1-mediated CRC development and is a potential target for CRC therapy. Colorectal cancer (CRC) is the second most common cause of death related to cancer in the world. A hallmark of CRC development is an aberrant activation of the Wnt/β-catenin pathway, already at an early stage of the disease, resulting in hyperactivation of β-catenin-TCF target gene expression –3. OvertWe wished to determine the proteins and signaling pathways that are involved in L1-mediated progression of colorectal cancer (CRC). We employed the LS 174T human CRC cell line stably overexpressing L1 and compared the proteins secreted into the conditioned medium of these cells using mass spectrometry , to thosTo determine the requirement for increased ISG15 in the tumorigenic properties conferred by elevated L1 expression, we isolated CRC cell clones overexpressing L1 in which the levels of endogenous ISG15 were suppressed using shRNA to ISG15 . In addiin vivo by s. c injection into immunocompromised mice  with a large number (hundreds) of proteins in the cell . We wishWe wished to determine the localization of ISG15 expression in human CRC tissue. Thirty-nine human CRC tissue samples were analyzed by immunohistochemistry with antibodies to ISG15 . We obseISG15 gene promoter, supporting the involvement of NF-κB in regulating the transcription of the ISG15 gene [In this study, we showed that among the proteins whose levels are most dramatically elevated by L1-overexpression in CRC cells is the ubiquitin-like interferon induced gene 15 (ISG15). We detected a significant increase in ISG15 both in the secretome and in cultured human CRC cells overexpressing L1. The increase in ISG15 was required for the pro-tumorigenic and metastatic properties involving increased cell proliferation under stress, enhanced cell motility and metastasis to the liver that are conferred by L1-expression in CRC cells. Interference with L1-mediated signaling by point mutations in the L1-ectodomain that are known to affect its adhesive properties and abolish its tumorigenic and metastatic properties , and whiG15 gene .ISG15 is suggested to operate much like ubiquitin and brings about the conjugation (ISGylation) of ISG15 to a wide variety of proteins (between 100–300 proteins)  and bothIn addition to its conjugation to target proteins, ISG15 was detected as an unconjugated protein, and in its free form ISG15 was suggested to function as a cytokine and as an intracellular interacting partner, acting independently of its conjugation to a target protein . In our The cell line LS 174T was grown in RPMI medium-1640  containing 10% FBS  and penicillin/streptomycin solution . LS 174T-L1, LS 174T-ISG15, LS 174T-L1/D598N and LS 174T-L1/H210Q cells  were maiThe ISG15 expression vector was obtained from Dr. Y. Song . ShRNA to ISG15 was prepared using pSUPER. puro by following the manufacturers protocol . The target sequences used for the preparation are described in Antibodies used for immunoblotting were: rabbit anti-L1  at 1:8,000 dilution, mouse anti-ISG15, sc-166755  diluted 1:1,000, rabbit anti-phospho-IκBα #2859  diluted 1:1,000, rabbit anti-NF-κB p65, sc-109  diluted 1:1,000, mouse anti-GAPDH, sc 47724  diluted 1:2,000, mouse anti-β-tubulin  diluted at 1:5,000. Cells were lysed in RIPA buffer [Western blots were developed using the ECL method . To analyze proteins secreted into the cell culture medium, cells were grown until confluence and the medium was replaced with medium without FBS for 24 hours. The medium was collected and centrifuged at 4,500 rpm for 10 minutes to sediment cell debris and the supernatant was filtered through a 0.22 μm syringe filter. The filtered medium was mixed with cold ethanol at a 3:1 ratio and with NaCl  and incubated overnight at ‒20°C and the denatured proteins were precipitated by centrifuging at 15,000 RPM for 30 minutes. Protein levels in cell lysates were determined by the BCA assay and the precipitated proteins were suspended in Laemmli’s SDS-PAGE loading buffer.For immunofluorescence, cells cultured on glass coverslips were permeabilized with 0.5% Triton X-100 in 4% PFA for 2 minutes . The priTotal RNA was isolated from cells using the Bio-Tri reagent  according to the manufacturer’s protocol. First strand cDNA was synthesized using the SuperScript™ II Reverse Transcriptase . The ISG15 primers used were, forward: 5′-GAGAGGCAGCGAACTCATCT, reverse: 5′-AGCATCTTCACCGTCAGGTC. Data analysis was performed employing the ΔΔCT method with the StepOne software v2.3 .The mass spectrometry analysis of the medium collected from LS 174T and LS 174T-L1 cells was performed at the proteomic unit of the Weizmann Institute of Science, as previously described .6 cells were injected into 5 different sites in the flanks of male nude mice [6 cells in 20 μl PBS into the distal tip of the spleen of 6 weeks-old male nude mice as described [Subcutaneous tumor growth was induced as described . Brieflyude mice . The abiThe Ethics Committee of the Weizmann Institutional Animal Care and Use (IACUC) reviewed, approved and supervised the animal studies (Permission number 11530219-2).Immunohistochemistry was carried out on 39 paraffin-embedded human colorectal adenocarcinomas using a rabbit anti ISG15 antiserum (antibodies-online #ABIN2844984), diluted 1:150, as previously described .P value of < 0.05 was considered significantIn the mouse metastasis experiments, statistical significance between the pcDNA3 and ISG15 cell clones was determined by the Wilcoxon Signed-rank test. The significance in the differences between L1 and L1+shISG15 cell clones was determined using the Mann-Whitney test. The significance of all other comparisons was determined by ANOVA. A


Ultrasound energy is a green and economically viable alternative to conventional techniques for surface modification of materials. The main benefits of this technique are the decrease of processing time and the amount of energy used. In this work, graphene nanoplatelets were treated with organic acids under ultrasonic radiation of 350 W at different times (30 and 60 min) aiming to modify their surface with functional acid groups and to improve the adsorption of uremic toxins. The modified graphene nanoplatelets were characterized by Fourier transform infrared spectroscopy (FT–IR), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The optimum time for modification with organic acids was 30 min. The modified nanoplatelets were tested as adsorbent material for uremic toxins using the equilibrium isotherms where the adsorption isotherm of urea was adjusted for the Langmuir model. From the solution, 75% of uremic toxins were removed and absorbed by the modified nanoplatelets. This process occurs at temperatures between 40–90 °C for 2 h [Nowadays, Diabetes mellitus, systemic arterial hypertension, increased weight, and obesity have a high impact on human health. All of these can cause chronic kidney disease (CKD), which is a complex disease. CKD represents 70% of all deaths in the US and México, with CKD being one of the main ten mortality causes in the last decade . CKD can for 2 h . The adv for 2 h . The aim of this study is to perform a surface modification of graphene nanoplatelets by a combination of organic acids, citric acid with oxalic acid and citric acid with formic acid, and ultrasonic irradiation with different sonication times to determine the adsorption of uremic toxins on these graphene nanoplatelets. Graphene nanoplatelets (10 to 12 layers) with a purity of 97%, with a diameter of 2 to 3 µm, identified as industrial-grade graphene nanoplatelets, were purchased at Cheap Tubes, Inc. . Citric acid, oxalic acid, and formic acid have a purity of 99% and were acquired from Sigma Aldrich . Distilled water with a pH of 7 was used in all aqueous solutions.The treatment was performed by dispersing 2 g of graphene nanoplatelets into 100 mL of distilled water with a combination of citric and oxalic acid; or citric and formic acid; in a 1:1 ratio, using a digital ultrasonic processor from Cole-Parmer model CPX750 , operated at 20 ± 0.1 kHz, with an output power of 750 W, at an amplitude of 50%, in continuous mode and plugged into a catenoidal titanium horn of 25 mm in diameter. For safety reasons, all experiments were done into a sound-abating enclosure. Two different treatment times of 30 and 60 min were applied. All experiments were performed at room temperature. At the end of the experiments, the graphene nanoplatelets were washed several times with distilled water until it reached a neutral pH, filtered and dried at 80 °C for 24 h.The materials were characterized by TA Instruments thermogravimetric analyzer (TGA) , which was used to examine the thermal stability of samples within a temperature range from 30 to 600 °C, at 10 °C/min, under nitrogen flow of 50 mL/min. From 600 to 800 °C, the nitrogen flow was changed to oxygen flow, at the same 50 mL/min, in order to obtain the total oxidation of the sample. −1, in the range of 400 to 4000 cm−1. Previously, the samples were dried in a vacuum oven  at 100 °C for 15 h, and thereafter they were supported in KBr pellets. The XPS (X-ray photoelectron spectroscopy) study was realized in the K-ALPHA spectrophotometer   with a monochromatic X-ray source with binding energy of 0–1350 eV and a depth of 400 μm, there is no pre-treatment to the samples. The X-ray powder diffraction data were collected on a Rigaku-smartlab diffractometer, operating at 40 kV and 40 mA with stability of 0.01%/8 h. Measurements of each system were performed in the scattering 2Θ range of 5° to 70°with a step of 0.02 and counting rate of 10 s/step. The quantification of acid groups was determined quantitatively by its acid-base titration. The methodology for the titration was based on the method of Bohem, which consists of placing 5 mL of a solution of 0.01 N of NaOH in 0.01 N NaCl in a matrix containing 10 mg of oxidized graphene. The samples were sealed and placed on a shaking rack at room temperature for 24 h, and then filtered and titered with 0.01 N HCl in NaCl solution. Fourier-transform infrared spectroscopy was recorded using a Magna Nicolet 550 spectrometer  with 100 scanner and resolution of 16 cmThe urea and uric acid were dissolved in distilled water separately at different concentrations  to create a calibration curve, which was read in the UV-Vis spectrometer Shimadzu model UV-1800 . The adsorption experiments were performed in precipitation glasses of 50 mL with 20 mL of solution of 160 mg/L (urea or uric acid) and 50 mg of unmodified and modified graphene nanoplatelets. The precipitation glasses were placed in a stirring plate at 37 °C and a stirring speed of 100 rpm, for 4 h, similar to the hemodialysis treatment time. Each 15 min a sample was taken and read in the UV-Vis spectrophotometer. The experiments were performed twice for reproducibility; the data given in the manuscript are the average values. Absorbance was measured by sampling at regular intervals. The concentration of uremic toxins in the solution was determined using the Beer–Lambert law by monitoring absorbance versus wavelength with λmax 200 and 293 nm for urea and uric acidThe removal percentage was calculated according to the following equation:Equation (1).m is the mass in mg of adsorbent.Equation (2).2) was calculated using the trendline command in Microsoft Excel. The Langmuir isotherm was calculated using the following equation:Langmuir and Freundlich models can describe the adsorption equilibrium. To test both models, absorption isotherms data were fitted and the correlation coefficient (R−1) and Ce (mg L−1) are the concentrations of the solid phase and liquid phase of the adsorbate in equilibrium, respectively, qm is the maximum adsorption capacity and KL is the constant obtained from plotting Ce/qe versus Ce.Equation (3).The Freundlich isotherm was calculated using the following equation:F (mg g−1) (L mg−1) and 1/n are the Freundlich constants related to adsorption capacity and n is the heterogeneity calculated with the lineal plot of lnqe versus lnCe. Equation (4).−1 corresponding to the bond formed by O-H in the samples was observed. This peak is not observed in the sample oxalic+citric60, likely due to the degradation of graphene and/or acid evaporation induced by the increase in the ultrasonic dose [nic dose . −1 and C-O vibration (from C-OH) at 1178 cm−1. These results are similar to those reported by Wang et al 2016 [−1 of oxalic+citric30 and oxalic+citric60 is due to COOH bond stretching vibration of the carboxylic acid. The FT–IR band at 1575 cm−1 was attributed to the carboxylate groups. These characteristic peaks indicate that large amounts of oxygen-containing functional groups exist on the graphene surface. All the samples exhibit the following characteristic signals: C=O stretching (from -COOH) at 1715 cm al 2016  for tart−1 corresponding to the bond C=O and C-O vibration at 1200 cm−1, these bands can be observed in the Formic+citric30 and formic+citric60 samples [−1, due to the presence of hydroxyl groups [−1 had a peak that was of greater intensity for the sample formic+citric30 compared to formic+citric60. samples . HydroxyThe XPS spectra of unmodified and modified graphene with oxalic+citric samples are seen in 2 carbon bond in graphene gradually decreased due to the addition of carboxylic groups on their surface, thus the chemical state of graphene was modified [modified . The sam4 in H2SO4 as an oxidizing agent. 2 and other compounds.Thermogravimetric analysis is shown in The XRD spectra measured in a range of 2theta from 5° to 70° . The intBased on the TGA, FT–IR, and XPS results, Uremic toxins can be classified based on their principal physicochemical characteristics that affect the solute elimination by dialysis. Special attention has been applied to uremic toxins of low molecular weight like urea and uric acid, which in general are used for adsorption tests . Figure 2. The result of the adsorption tests was based on the comparison of RBased on the above results, the following scheme is suggested for the adsorption mechanism. The acidic functional groups attached to graphene nanoplatelets can bind toxins (urea) by an attraction between the free electron pair of oxygen in the carbonyl functional group with the free electron pair of nitrogen of a urea molecule. At the same time, the hydroxyl functionality of the graphene surface could interact with the amine and carbonyl group of urea  by meansThe modification of graphene with organic acids and ultrasonic radiation was carried out successfully, as revealed by XPS, after deconvolution of the C1s peak, C-O and O-C=O bonds were found. The optimum experimental condition for reaching this modification was a combination of oxalic and citric acids in a ratio 1:1, and a time treatment of 30 min. The ultrasonic radiation promotes the attachment of acidic functionalities on the surface of graphene, but when the exposure time is increased, structural damage could occur.2SO4/HNO3 mixtures is the shorter reaction time, as it has been reported that times longer than 1 h for acidic oxidation with H2SO4/HNO3 produces serious modifications of the graphene network, limiting further potential applications. However, this method is considered green because it fulfills two principles of green chemistry, which are the use of renewable raw materials and alternate energies such as ultrasound.The advantage of this method compared to that of HUrea adsorption was achieved in all materials of modified graphene. Oxalic+citric30 material had a high level of adsorption (75%) and adjusted very well with the Langmuir isotherm, indicating that adsorption phenomena occurs by a monolayer formation, and that it is a good candidate as an adsorbent material for hemodialysis treatment. In contrast, uric acid adsorption in all modified graphene samples showed a poor adsorption value of 35%.The feasibility of adding modified graphene  to a polymeric membrane for enhancing its efficiency in the adsorption of uremic toxins makes this material an alternative for improving hemodialysis treatment.