Ultimately, zinc oxide (ZnO) nanoparticles were deposited into these two-dimensional heterostructures to produce an artificial ZnO/MoS2/graphene nanocomposite. This new composite experimentally exhibited an excellent photocatalytic efficiency in hydrogen evolution under the sunlight illumination (2. Moreover, due to the synergistic effects in MoS2 and graphene, the lifetime of excited carriers increased dramatically, which considerably improved the photocatalytic efficiency of the ZnO/MoS2/graphene heterostructure. We conclude that the novel artificial heterostructure presented here shows great potential for the high-efficient photocatalytic hydrogen generation and the high throughput production of visible-light photocatalysts for industrial applications.High-throughput production of highly efficient photocatalysts for hydrogen evolution remains a considerable challenge for materials scientists. Here, we produced extremely uniform high-quality graphene and molybdenum disulfide (MoS In recent decades, various methods and nanostructures have been developed to realize efficient hydrogen generation ,2. As exformance ; and Pd-formance . HoweverLow-dimensional nanomaterials, such as quantum dots and two-dimensional materials, are expected to be the new-generation photocatalytic materials because of their excellent physical and chemical properties. Zinc oxide (ZnO) nanoparticles are emerging as a competitive photocatalyst, due to their outstanding photoelectricity, regulable band gap, and extremely high electron densities ,9. Howev2/graphene heterostructure, in which MoS2, generally considered to be a layered n-type semiconductor with a suitable band gap for the absorption of visible light, serves as an interlayer to the sunlight absorption and thus improves the photocatalytic efficiency [2 also significantly enhances the transportation of excited carriers in the composite, leading to a higher photocatalytic efficiency [Graphene, the ‘superstar’ of two-dimensional materials with excellent electric, thermal, and mechanical properties ,16,17, wficiency ,25,26. Ificiency ,28.2 by the electrochemical-assisted liquid-phase exfoliation method [2/graphene van der Waals heterostructures [2/graphene nanostructures to form ZnO/MoS2/graphene ternary heterostructures. Relying on the extremely-high carrier mobilities and the large effective surface of graphene nanoplates, as well as the enhanced visible-light absorption of the electron-transport-layered MoS2 [2/graphene heterostructure.In this work, we exfoliated graphite into high-quality graphene nanoplatelets in solvents, produced high-quality layered MoSn method , and assructures . Next, Zred MoS2 ,32,33,34red MoS2 . Our syn−1). In order to evaluate the morphology and quality of these samples, a small quantity of diluted graphene solution was dropped on the 300 nm SiO2/Si wafer and dried for further characterizations by scanning electron microscopy (SEM) and Raman spectroscopy.Graphene nanoplatelets were produced by dispersing expanded highly oriented pyrolytic graphite  in N-methyl-pyrrolidone  solvent via bath sonication (100 kHz) for 10 h at 60 °C . After t2 nanoplatelets by electrochemical-assisted liquid-phase exfoliation methods. First, we pretreated the MoS2 crystals to be expanded to be bulk MoS2 by using the electrochemical method previously reported by Duan’s group [2 crystal was sonicated in the dimethylformamide (DMF) solvent with the stabilizing-agent Poly-vinylpyrrolidone , which effectively minimized the re-stacking of the MoS2 nanoplatelets for 6 h to obtain the MoS2 nanoplatelets. After the sonication and centrifugation processes were repeated, various concentrations (up to around 5 mg ml−1) of MoS2 solutions were produced. The solution exhibited a uniform yellow color due to the strong absorption of visible light by MoS2. The SEM and Raman spectroscopy data were collected by dropping the MoS2 nanoplatelets onto the surface of a 90 nm SiO2/Si wafer.Similar to the preparation of graphene nanoplatelets, we prepared MoS’s group . The exp3COO)2·2H2O; 99.999%, Sigma-Aldrich, Shanghai, China) was refluxed and dissolved in 10 mL ethanol at 80 °C. A potassium hydroxide solution, prepared from 95 mg of potassium hydroxide  sonicated in 10 ml ethanol, was slowly added dropwise to the zinc acetate solution in a water bath at 50 °C under magnetic stirring. The reaction conditions were maintained for 1 h, and the resulting transparent solution was kept overnight, extracted with n-hexane and ethanol, washed, and air-dried. In the process of synthesizing ZnO nanoparticles, 22 mg of zinc acetate dihydrate , to ultimately produce the ZnO/MoS2/graphene heterostructures shown in First, in order to assemble the MoS2 were obtained using confocal Raman spectroscopy  with a 488 nm laser wavelength, a 10 mW laser energy power, and a 300 nm resolution. The morphology of the nanomaterials was obtained by imaging using a scanning electron microscope . The components were detected by x-act with INCA and Aztec energy-dispersive X-ray spectroscopy (EDS) analysis software . The morphology and size of ZnO nanoparticles were measured by transmission electron microscope  with an accelerating voltage of 300 kV. The X-ray diffraction patterns of the samples were tested using an X-ray diffractometer  with Cu (Kα) at a speed of 2°/min. The structures were detected by the X-ray photoelectron spectrometer . The UV-visible spectra of the samples were recorded on a spectrophotometer .Raman spectra and mappings of graphene and MoS2S; Sigma-Aldrich #407410) and sodium sulfite . The resulting mixture was stirred for 1 h without light in order to obtain a uniform dispersion. In the meantime, the nitrogen gas was introduced to exhaust the oxygen of the reaction chamber. We exposed the Xenon lamp , with a 400 nm center-wavelength standard bandpass filter, continuously stirred the reactor, and then measured the light intensities by the optical sensor. Meanwhile, the generated hydrogen was collected and analyzed using gas chromatography .Hydrogen-generation photocatalytic measurements were conducted in a homemade quartz reactor system. Photocatalysts were placed into the deionized water with sacrificial reagents of sodium sulfide  was conducted on the samples of the MoS2/graphene heterostructure, the ZnO/MoS2 heterostructure, and the ZnO/MoS2/graphene ternary heterostructure, respectively. The typical element components of each material were measured, which further confirmed the formation and existence of these heterostructures, as shown in The SEM characterization of the morphology of prepared MoS2, and the ZnO/MoS2/graphene ternary heterostructures. For pure ZnO nanocrystals, the diffraction peaks appeared at 2θ = 31.3, 34.6, 36.1, 47.7, 56.2, 62.9, and 67.7; these peaks can be attributed to (100), (002), (101), (102), (110), (103), and (112) lattice planes, respectively. A comparison of the XRD patterns with the (100), (002), (101) and other diffraction peaks of standard ZnO materials demonstrates the existence of a polycrystalline hexagonal wurtzite crystal orientation for ZnO [2/graphene, it was easy to see that the (100), (002), and (101) diffraction peaks had a slight left shift, indicating that the ZnO lattice constant became larger due to the strong interactions of van der Waals forces in the heterostructures. Moreover, with respect to the pure MoS2 nanosheets, we compared the diffraction peak positions with the standard card JCPDS 37-1492, which was consistent with our results, proving that the product is a hexagonal phase. Moreover, the presence of the (002) peak indicated a good crystallization of the sample. The XRD diffraction spectrum of graphene nanoplatelets exhibited a standard graphene diffraction peak at 2θ = 26°, which was different from the diffraction peak of graphene oxide at 2θ = 10°. This indicates that there are no damages or defects between the layers of graphene, as proof of its excellence. Regarding the ZnO/MoS2/graphene heterostructures, they mainly exhibited the diffraction peak characteristic of ZnO, owing to the fewer components of graphene and MoS2 in the composition. The structural analysis of the various items and their components was performed using XRD, XPS, Raman, and PL spectroscopy.  for ZnO . When we2 hybridization in graphene [3/2 and 2p1/2 peaks of Zn-2p, respectively, which was assigned to the ZnO [3/2 and 2p1/2 of Zn-2p had a very slight shift. The reason may be that the formation of a heterojunction in the complex that promoted the charge transferring. In addition, we also observed Mo-3d and S-2p core levels at 228.4 eV and 162.1 eV in agreement to previous reports [4+ chemical state corresponding to MoS2. Moreover, considering that the MoS2 is prepared by a physical method (electro-assisted liquid-phase exfoliation method), almost no MoOx exists in the composite, resulting in the lack of another doublet peak of Mo-3d in the XPS result.Further, XPS spectra are shown in graphene . Further the ZnO . We can  reports ,42,43,442, and ZnO/MoS2/graphene were measured, as shown in 2 nanosheets as the excellent electron-transport-layered materials. However, after combining the graphene nanosheets with other materials to form the heterostructures, the D peak of the graphene in the composite became significantly higher, due to the influence of the internal effect in the heterojunction. Simultaneously, this effect was also found in the ZnO, which is evidenced by the left shift of the ZnO diffraction peaks in the XRD spectra. An explanation for this is that an increase of the lattice constant causes the occurrence of more oxygen-vacancy defects, which further results in an increase of the visible-light absorption capacity of the materials, eventually improving the catalytic efficiency of the composite. In addition, from the Raman spectra of ZnO/MoS2/graphene composite, we are able to explain the widening A1 and E2 peaks by the superimposition of the Raman signals from MoS2 and pure ZnO nanoparticles. To further characterize the quality of materials, the Raman spectra of ZnO, graphene, MoS2/graphene heterostructures at room temperature, as given in 2/graphene, the PL emission peak was reduced, indicating less photogenerated electron-hole recombination. The mechanism can be described as follows: The photogenerated electrons are more naturally diffuse into the graphene layer due to the excellent carrier mobility of graphene and the matched energy levels  spectra were also measured on the ZnO nanoparticles and ZnO/MoS2/graphene heterostructures and the electron transfer during the photocatalytic processes are illustrated in 2/graphene can be summarized as follows: (1) Introducing a MoS2 layer increases the specific surface area and inhibits the self-stacking of graphene nanoplatelets, providing more active sites [2 and graphene are reasonably matched, enhancing the electron transportation between layered materials; in this way, the possibilities of photogenerated electron-hole recombination are lowered. (3) As a two-dimensional material with higher carrier mobilities, graphene acts as an excellent electron acceptor. (4) The interlayer MoS2 serves as a visible-light absorbance material in this structure due to its adequate band gap. The band gaps of multi-layer MoS2 nanoplatelets and ZnO nanocrystals are 1.29 eV and 3.29 eV, respectively [2, as shown in 2, electrons can travel faster, which reduces the possibility of the recombination of electrons and holes [The designed ZnO/MoSve sites ,46,47,48ectively . Accordiectively . Considend holes ,51. Last2, and ZnO/MoS2/graphene. The hydrogen generation rate is nearly zero with the ZnO photocatalyst only, whereas ZnO/MoS2/graphene leads to maximum hydrogen generation. Due to the synergistic effect of MoS2 and graphene nanoplatelets, the recombination rate of photogenerated electron-hole pairs is strongly reduced. 2, and ~ 3% graphene. This phenomenon can be explained by the various roles played by ZnO, MoS2, and graphene in the catalytic process. A sufficient amount of ZnO nanoparticles provided a large number of photogenerated electrons, leading to an increase of the hydrogen generation rates of the photocatalysts [The photocatalytic activity was evaluated by measuring the ability of hydrogen generation under visible-light illumination in various photocatalysts. atalysts ,53,54. W2 photocatalyst prepared by Yuan et al. has a catalytic efficiency of about 0.8 mmol h−1 g−1 [2-graphene/ZnIn2S4 composite with a catalytic efficiency of about 4.2 mmol h−1 g−1 [−1 g−1 [2–Reduced Graphene Oxide composite with a catalytic efficiency of 28.6 mmol h−1 g−1 [2/graphene composite, whose catalytic efficiency can reach 5.4 mmol h−1 g−1 . As a comparison, we can conclude that this work provides a high-throughput method for preparing higher-efficiency photocatalytic materials, which has a driving role in the application of photocatalysis in industry.In comparison with separate studies referenced in this paper, the ZnO/MoS h−1 g−1 ; they al h−1 g−1 . Bhirud  [−1 g−1 . Kumar e h−1 g−1 . In this2/graphene sandwiched heterostructures. This new material was synthesized by taking advantage of the high electron densities of ZnO nanoparticles, the ultra-high electron mobilities and specific surface area of graphene nanoplatelets, and the enhanced visible-light absorption properties of MoS2, which allowed a highly efficient production of hydrogen by ZnO/MoS2/graphene enabled photocatalysis. Also, the production of these materials occurred mainly through chemical and liquid-phase exfoliations, which are suitable for large-scale industrial production. In summary, this work combined the excellent properties of zero-dimensional nanoparticles and two-dimensional nanomaterials, developed a novel layer-by-layer nanostructured photocatalyst, and eventually realized a highly efficient hydrogen production under sunlight. It opens new avenues for the high-throughput production of superior hydrogen-evolution photocatalysts that are of significant importance to a clean energy revolution. In this study, we presented a novel high-efficient photocatalyst based on the ZnO/MoS


Low-dimensional nanostructures and their complementary hybridization techniques are in the vanguard of technological advances for applications in transparent and flexible nanoelectronics due to the intriguing electrical properties related to their atomic structure. In this study, we demonstrated that welding of Ag nanowires (NWs) encapsulated in graphene was stimulated by flux-optimized, high-energy electron beam irradiation (HEBI) under ambient conditions. This methodology can inhibit the oxidation of Ag NWs which is induced by the inevitably generated reactive ozone as well as improve of their electrical conductivity. We have systematically explored the effects of HEBI on Ag NWs and graphene. The optimized flux for HEBI welding of the Ag NWs with graphene was 150 kGy, which decreased the sheet resistance of the graphene/Ag NWs to 12 Ohm/sq. Following encapsulation with graphene, the initial chemical states of the Ag NWs were well-preserved after flux-tuned HEBI, whereas graphene underwent local HEBI-induced defect generation near the junction area. We further employed resonant Raman spectroscopy to follow the structural evolution of the sacrificial graphene in the hybrid film after HEBI. Notably, the sheet resistance of the welded Ag NWs encapsulated with graphene after HEBI was well-maintained even after 85 days. Unfortunately, the use of these materials in practical applications has been hampered. For example, two-dimensional monolayer graphene possesses excellent optical transmittance (~97.7%)10, however, its doping and layer-by-layer stacking, which are required to decrease its intrinsic sheet resistance (300–1000 Ohm/sq)11, are plagued by issues such as doping stability, the presence of residual carbon, and complicated procedures. One-dimensional conductors, including Ag NWs and CNTs, also encounter insurmountable hurdles involving high wire-to-wire junction resistance and low corrosion resistance12. To overcome these issues, the complementary hybridization of nanostructures, in terms of their properties and effective welding processes to decrease the junction resistance, are highly required13. In previous studies, welding processes for randomly networked metallic NWs with low sheet resistance have included plasma treatment, UV-pulsed laser irradiation, thermal annealing, and pressure welding18. However, these approaches suffer from limitations such as requirements of large-scale fabrication and low-temperature processes for the application of plastic substrates for flexible nanoelectronics. In this study, we firstly established a unique and facile methodology for welding Ag NWs using high-energy electron beam irradiation (HEBI) under ambient conditions over a large area (90 × 90 cm2). In general, the structural manipulation of carbon nanostructures via knock-on collisions of highly energetic electrons has been carried out using transmission electron microscopy (TEM) under high vacuum21. In previous studies, the decoration of CNTs with Au, Ni, and Pt nanoparticles and the hybridization of graphene with ZnO thin films were performed using MeV electron beam irradiation under ambient conditions, to tune their electrical properties24. Here, we rationally designed that the welding of Ag NWs encapsulated in graphene was stimulated by flux-optimized HEBI under ambient conditions to inhibit the oxidation of the Ag NWs by the inevitably generated reactive ozone, as well as to improve their electrical conductivity. This strategy enables the hybridization of graphene with the Ag NWs to provide an additional conducting path, and to simultaneously passivate the HEBI-induced oxidation of the Ag NWs, which was previously explored in a similar system (graphene on Cu NWs)25. As a result, long-term, air-stable Ag NWs-graphene hybrid conducting films with a low sheet resistance could be obtained. Additionally, an in-depth study of the structural and chemical features of graphene and the welded Ag NWs after flux-optimized HEBI was implemented.It is widely recognized that the prerequisites for the development of high-performance transparent electrodes are high electrical conductivity and high optical transparency. To date, indium tin oxide (ITO) has been typically adopted for multi-purpose transparent electrodes in solar cells, touch panels, and organic light emitting diode panels. However, ITO films possess limitations to their application in next-generation, flexible nanoelectronics because of their physical inflexibility and high cost. Due to their intriguing optical and electrical properties, promising candidates such as metallic nanowires (NWs) and low-dimensional carbon nanostructures including carbon nanotubes (CNTs) and graphene have been developed as replacements for ITO films to fabricate key components of next-generation nanoelectronics26. Interestingly, the lowest sheet resistance of Ag NWs/SiO2 is 29 Ohm/sq with a flux of 200 kGy, and that of graphene/Ag NWs/SiO2 is 12 Ohm/sq with a flux of 150 kGy, as shown in Fig. 2 and graphene/Ag NWs/SiO2 increase significantly. Conversely, a negligible loss of the optical transmittance at 550 nm for the Ag NWs (83.0 ± 1.1%) and the graphene/Ag NWs (79.5 ± 1.1%) is observed after the flux-tunable HEBI  and TEM. Figure 2 with HEBI at a flux of 200 kGy, revealing that the two cross-stacked Ag NWs are welded unambiguously. For the graphene/Ag NWs/SiO2 with HEBI at a flux of 150 kGy, the Ag NWs are fully encapsulated in graphene and the formation of the wrinkle structure as well as electron-beam-stimulated welding of the Ag NWs can be observed in Fig. First, the effect of HEBI on the Ag NWs and the graphene/Ag NWs was explored, as depicted in Fig. 3d core level spectra of the Ag NWs/SiO2 after 1 MeV HEBI with a total flux of 120–600 kGy, revealing that the intensity of higher-binding energy oxidation states of the Ag 3d5/2 and 3d3/2 peaks increases with increasing HEBI flux. This result is strongly correlated with the variation in the sheet resistance of the Ag NWs after HEBI with a higher flux (>400 kGy). We mentioned earlier that HEBI was implemented under ambient conditions, whereby the oxidation of the Ag NWs occurs by the generation of reactive ozone. On the contrary, it should be noted that the initial chemical states of the Ag NWs encapsulated in graphene are well-preserved obviously, as shown in Fig. 1s core level spectra of the graphene/Ag NWs on SiO2 after HEBI with a total flux of 120–600 kGy, in which predominant sp2 C-C (EB = 284.5 eV) and oxygen functional groups including C–OH, C–O, and C=O combined with PMMA-induced bonding states are observed. The formation of PMMA residue on the graphene surface is thought to be induced by the PMMA-mediated wet transfer process. Interestingly, with an increase in the total flux of the HEBI, the intensity of the PMMA-related peaks decreases gradually. This phenomenon can cause a reduction of the sheet resistance when increasing the total flux of the electron beam irradiating the pristine graphene, as displayed in Fig. 29. The long-term stability of sheet resistance for the Ag NWs and the graphene/Ag NWs on SiO2 after HEBI with a total flux of 150 kGy was confirmed by elucidating the protection effect by the gas barrier property of graphene, as seen in Fig. The effects of flux-tunable HEBI on the chemical states of the Ag NWs and the graphene/Ag NWs hybrid films were explored by XPS. Figure D/IG) correspond to 1.52 and 0.10, respectively, indicating the synthesis of monolayer graphene with a highly crystalline structure, which is confirmed by the SAED pattern  compared with that in the graphene-only region (green circle). This phenomenon can be explained by the effect of the Ag NWs-driven surface enhanced Raman scattering30. The ID/IG map reveals that the relative intensity of the D-band for graphene significantly increases in the graphene/Ag NWs region. Figure From a different standpoint, we also focused on the structural evolution of graphene in graphene/welded Ag NWs hybrid films after HEBI. Resonant Raman spectra recorded at an excitation wavelength of 532 nm from graphene, graphene/Ag NWs, and graphene/welded Ag NWs are measured, indicating that graphene fingerprints including the D-, G-, and 2D-bands are observed, regardless of the film type  is displayed in Fig. 2). However, the size of the hybrid film was restricted inevitably due to limitation of the CVD system for graphene growth. In order to assess the capability in flexible electronics, the variation in resistance (ΔR/R0) for the hybrid film is examined by adjusting the bending radius , as shown in Fig. 4 cycles, as seen in Fig. 31.The optical transmittance at a wavelength of 550 nm of the Ag NWs and the graphene/Ag NWs after HEBI with a flux of 150 kGy corresponds to 83% (sheet resistance: 43.2 ± 5.9 Ohm/sq.) and 81% (12.9 ± 1.6 Ohm/sq.), respectively, as seen in Fig. In summary, we have demonstrated the welding of Ag NWs encapsulated in graphene formed by flux-optimized HEBI under ambient conditions over a large area. After the HEBI-stimulated welding process with a flux of 150 kGy, the sheet resistance of the Ag NWs with graphene decreased significantly. Because of the encapsulation in graphene, the initial chemical states of the Ag NWs were invariant, and local oxidation of graphene occurred on behalf of the Ag NWs. We systematically studied that the effect of HEBI the sacrificial oxidation of graphene extended to only 60 nm away from the welded Ag NWs junction. Remarkably, the sheet resistance of the welded Ag NWs encapsulated in graphene after HEBI remained relatively unchanged after 85 days. It is envisaged that this methodology will result in an increased demand for transparent and flexible electrodes with high electrical stability.2 (300 nm)/Si(001) substrate at a rotational speed of 3000 rpm for 30 s, and then immediately heated to 150 °C for 5 min to remove the solvent. Next, graphene was synthesized using a conventional thermal chemical vapor deposition (TCVD) system. A 25 μm-thick Cu foil  was utilized as a catalytic substrate for the synthesis of graphene. The Cu foil was loaded into the TCVD chamber and pre-annealed at 1050 °C with introducing H2 (200 sccm) under a pressure of ~3.6 Torr for 2 h in order to reduction and surface flattening of the Cu catalytic substrate. After the pre-annealing process, the graphene was immediately synthesized through the introduction of CH4 (2 sccm) and H2 (200 sccm) for 80 min. Following the growth of the graphene, the TCVD reactor was cooled down to room temperature with H2.First, a 0.5 wt.% solution of commercially available Ag NWs  in isopropyl alcohol was spin-coated onto a hydrophilic-treated SiO2 using a poly(methyl methacrylate) (PMMA)-assisted wet transfer technique. Nano-welding of the Ag NWs was accomplished through high energy electron beam irradiation (HEBI) of the graphene/Ag NWs hybrid films. A 1 MeV electron accelerator  was adopted for HEBI with the extraction window of 1200 mm in width. The total flux of the electron beam can be manipulated by adjusting the irradiation time at a dose rate of 33.3 kGy/sec. The samples were irradiated with a total flux of 30, 60, 90, 120, 150, 180, 200, 400, or 600 kGy under ambient conditions.The synthesized graphene was transferred onto the Ag NWs/SiO−9 Torr) with a pass energy of 50.0 eV. The structural feature of the hybrid films was investigated using micro Raman spectroscopy . The structural characterization of the samples was carried out using scanning electron microscopy  and TEM  with electron energy loss spectroscopy . The sheet resistance of the samples was measured by 4-point probe measurement system . The optical transmittance of the hybrid films was examined by UV-visible spectroscopy .The chemical identification of the hybrid films was conducted using X-ray photoelectron spectroscopy . The XPS spectra were recorded with a normal emission geometry using monochromatic Al Kα radiation (hν = 1486.6 eV) in an ultrahigh vacuum system (pressure: ~10Supplementary Information


This allowed us to avoid confounds and biases involved in relying on observers’ response , which contaminated previous measurements of this window. We presented letters to the right and left of fixation, each surrounded by task-irrelevant disks with varying distances. The disks were bright on one side and dark on the other. A central cue indicated which letter to attend. Luminance levels were identical across trials. We found that pupil size was modulated by the disks’ luminance when they were 1° away from the attended letter, but not when this distance was larger. This suggests that the diameter of the attentional window is at least 2°, which is twice as large as that established with behavioral measurements.This study measured the size of the attentional window when attention is narrowly focused, using attentional modulation of the pupillary light response – pupillary constriction when  Others showed that the size of the attentional window can be voluntarily modulated3. Additionally, it was suggested that the size of the attentional window plays a critical role in attentional capture, as attention can only be captured by stimuli appearing within the attentional window5. Eriksen and Hoffman6 further suggested that the size of the attentional window can be narrowed down to a diameter of about 1° of visual angle . Critically, most of the previous studies explored the characteristics of the attentional window using behavioral measurements, particularly reaction time (RT). For example, Eriksen and Hoffman6 presented a target letter flanked on each of its sides by two irrelevant letters (distractors). Target and distractors were chosen from the same set of four letters , and target identification RT was measured under three target-distractor distances: 0.53°, 1.0°, and 1.4°. They found no significant difference between the second and third distance conditions, but RT was significantly slower with the smallest distance. This led Eriksen and Hoffman to conclude that only with the distance of 0.53° the distractors were included within the attentional window. However, behavioral measurements could be affected by various factors that are not directly related to the size of the attentional window, such as higher-level strategies, decisional criteria, experience, learning, speed accuracy tradeoffs, response biases, etc. This is particularly so with RT, as it also involves factors related to motor preparation. The goal of the current study, therefore, was to estimate the minimal size of the attentional window , with a measurement that is independent of performance – the pupillary light response (PLR).Spatial covert attention refers to processes that prioritize information gathered from a specific location, in the absence of eye movements. The attentional window is defined as a restricted region in our visual field to which spatial attention is deployed. Many studies examined the characteristics of the attentional window. For instance, several studies suggested that the size of the attentional window varies with task demands7. For many years the PLR was considered a reflex that is mediated by low level, subcortical, mechanisms9. Interestingly, recent studies demonstrated that spatial covert attention can also affect the PLR. Under identical overall luminance conditions, covertly shifting spatial attention to a brighter area produces pupillary constriction relative to shifting covert attention to a darker area14. For instance, Binda et al.10 presented two disks, each with a dot at its center, against a uniform gray background. One disk was presented to the right and the other to the left of a central fixation mark. Additionally, one disk was bright and the other one was dark. A central cue instructed observers to covertly attend one of the disks while fixating the central fixation mark. The task was to count the number of times the dot on the attended disk changed its color. The results showed that pupil size depended on where spatial covert attention was focused: when the bright disk was attended pupil size was smaller relative to when the dark disk was attended. Similar results were found by Mathôt et al.11 and further extended to involuntary allocation of covert spatial attention12. We used these attentional modulations of the PLR to assess the spatial extent of attention without having to rely on performance. Specifically, we employed a task requiring the participants to focus their attention narrowly on a target, and added to the display task-irrelevant stimuli of different levels of luminance. The irrelevant stimuli were presented at varying distances from the target. As long as these distances were small enough so that the irrelevant stimuli fell within the attentional window, we expected to find a brightness effect: smaller pupil size when covert attention is directed to a target surrounded by bright than dark irrelevant stimuli. Once the irrelevant stimuli appear at a distance larger than the attentional window, their luminance should not affect pupil size. This allowed us to estimate the size of the attentional window.It is well known that the pupils change their size in response to light – they constrict when light levels are high and dilate when light levels are lowWe conducted two such experiments, in which we presented two squares to the right and left of the fixation Fig. . Each sqTwelve observers participated in this experiment. All observers were students from the University of Haifa, with normal vision and without diagnosis of attention deficit disorder. All observers signed an informed consent form. Observers were naive to the purpose of the study and were either paid or received course credit for participating. This study adhered to the Declaration of Helsinki, and was approved by the ethics committee of the University of Haifa.15 in MATLAB on a 19-in. monitor of an IBM-compatible PC . Pupil diameter and eye movements were recorded from the right eye with an EyeLink 1000 eye tracker . Two squares  were presented at an eccentricity of 6.75° to the right and left of a central square fixation mark (1° × 1°). An arrow (0.7° × 0.7°) pointing to the right or the left appeared inside the central square, and a rotating letter T (1° × 1°) was displayed inside each of the other squares against a static random dot noise that filled each square . The Ts could be oriented upright, inverted, 90° to the right or to the left, and they changed their orientation randomly and independently. The luminance of the Ts was set individually for each observer to avoid performance that is too high or too low . This was established based on the practice session. If performance was either very high or very low in the practice session the experimenter changed the luminance of the T in the experimental session accordingly to make the task harder or easier . The contours of all squares and the arrow were colored in isoluminant red (24.5 cd/m2), and the background was a uniform gray (24.5 cd/m2). A group of four disks surrounded each T with varying inter-stimuli distances. The distances from the center of each T to the inner edge of the disks that appeared above and below the T were 1°, 4°, 7° and 11° of visual angle. The distances of the disks that appeared diagonally above and below each T were 1.5°, 4.5°, 7.5° and 11.5°. Each disk had a diameter of 1°. The disks were bright (90 cd/m2) on one side of the screen and dark (0.04 cd/m2) on the other side.Stimuli were presented using the Psychophysics Toolbox extensionsAt the beginning of the session, observers were instructed to look only at the center and avoid blinking throughout each trial, but were encouraged to take short breaks between trials and long breaks between blocks. Then, a 9 points calibration was conducted. Each trial was preceded by a drift check to ensure the accuracy of the calibration is maintained and that the participant looks at the center. A trial started with the central fixation mark and the squares. After 1 sec, the arrow appeared inside the central square indicating the side to which the observers have to attend, and it was presented till the end of the trial. After 2 sec, the disks and rotating Ts appeared simultaneously. The Ts changed their orientation every 500 ms, and were visible for 6 sec. The target was the letter T on the attended side, and the task was to count the number of times the attended target assumed an upright orientation, while looking at the center of the fixation mark. Following a response, an auditory feedback indicated whether or not the response was correct. The distance between the target and disks was constant within a block and varied between blocks. The experiment included 448 experimental trials. For 10 out of the 12 participants these 448 experimental trials were divided into 4 sessions of 112 trials. These sessions were conducted on different days to minimize fatigue or at the same day if the participant could rest for at least two hours between sessions. In each session there were two blocks, each of a different target-disks distance. The order of distances was random, but to avoid order effects each distance appeared once as the first block of a session and once as the second block of a session. For 2 observers the 448 experimental trials were divided into 2 sessions of 224 trials, which included 4 blocks each. For all 12 participants, each experimental session was preceded by a practice session that included 20 practice trials. These practice trials did not include the disks in order to motivate the observers to concentrate only on the task. In addition, before the beginning of each experimental block, there were 5 practice trials that were identical to those of the upcoming experimental block. The side at which the bright (dark) disks were displayed, and the side to which the arrow pointed were chosen randomly for each trial and were counterbalanced across the entire experiment.10 . At first, blinks events were linearly interpolated17. Then, the sampling points of pupil size were averaged within 50 ms time bins. The baseline was the average pupil size of the 100 ms preceding the onset of the disks and Ts. For each trial, the average pupil size of each bin was divided by the baseline value. We performed a linear mixed effects analyses (LME) for each bin, using R’s lme4 package19. The variable of pupil size was entered into the model as the dependent measure and the variable of subjects served as a random effect. To test for a difference between the disk brightness conditions , as well as the effect of target-disks distance, the variables of brightness and target-disks distance as well as their interaction were entered to the model as fixed effects. Additionally, to examine in more details the relationship among these two variables, we conducted a separate analysis for each target-disks distance with disks brightness at attended side as a fixed effect. Similar to previous studies, we defined the significance criterion as t > 2 for at least 200 ms time interval21.We included in the analyses only trials in which fixation was not broken more than 1° and pupil size ranged between 2 to 8 mmhttps://osf.io/tg5n9/?view_only=3039239e39104ee292700b5cdf022f8c.The data that support the findings of this study are available in the Open Science Framework repository, 23. In addition, with all four distances there was a gradual increase in pupil size as the trial advanced, regardless of disks brightness. Such gradual increase was also demonstrated before, and it is probably due to cognitive effort associated with the task25. More important for the goal of this study, we found a significant interaction between brightness and distance. Further analyses performed for each distance separately revealed a significant brightness effect with the smallest distance of 1°: Pupil size was smaller when the attended target was surrounded by bright than dark disks. Critically, this difference was not significant at any time along the trial with the other larger distances. Hence, the results suggest that disks that were presented at a distance of 1° from the target fell within the attentional window, whereas disks that were presented at a distance of 4° or larger fell outside the attentional window.The results are presented in Fig. To establish a more accurate estimation of the attentional window, we performed Experiment 2, which was similar to Experiment 1, but examined the attentional effect on the PLR with a finer scale of distances .Twelve observers participated in this experiment, of which 6 also participated in Experiment 1. All observers were students from the University of Haifa, with normal vision and without diagnosis of attention deficit disorder. All observers signed an informed consent form. Observers were naive to the purpose of the study and were either paid or received course credit for participating. This study adhered to the Declaration of Helsinki, and was approved by the ethics committee of the University of Haifa.2 in Experiment 2 with a mode of 19 cd/m2. The distances from the center of each T to the inner edge of the disks that appeared above and below the T were 1°, 2°, 3° and 4°, and from the diagonally upper and lower disks were 1.5°, 2.5°, 3.5° and 4.5°. The presentation duration of the Ts was shortened to 4 sec. This was motivated by the fact that no effects of interest emerged at the last 2 sec of the trials in Experiment 1. With all the participants, the 448 experimental trials were divided into 4 sessions of 112 trials, as described for Experiment 1.The stimuli, apparatus and procedure were similar to Experiment 1 except for the following. The luminance of the Ts ranged between 15 to 21 cd/mStatistical analyses were identical to those of Experiment 1 . A similar significant brightness × distance interaction emerged Fig. : With th6. Experiment 2 further shows that disks that where presented at a distance of 2° or more, fell outside the attentional window, suggesting that the diameter of the attentional window is smaller than 4°. It is important to note that the distribution of attention is likely not uniform but rather falls gradually from the center of the attentional focus27, and that there is evidence for individual differences in the spreading of attention29. Such individual differences and general noise in the data may deem impractical an attempt to establish a finer estimation of the size of the attentional window, at least when looking for the minimal size.The results of both experiments demonstrate that disks that where presented at a distance of 1° from the target fell within the attentional window, even though they were task-irrelevant. If the attentional window is viewed as a round window centered at the target, then our findings propose that the diameter of this window is at least 2°. This suggests that the minimal size of the attentional window is twice as large as that found with behavioral measurements33. The typical way by which these studies measured the size of the attentional window was to measure distractor interference as a function of target-distractor distance; when distracting stimuli influenced performance it was concluded that they fell inside the attentional window33. However, this conclusion was debatable, because a large body of evidence suggests that unattended visual stimuli are also processed and can affect performance37. Hence, the mere fact that performance was affected by distracting stimuli does not necessarily mean that these stimuli fell within the attentional window. Likewise, the lack of response interference may not necessarily mean that the distracting information fell outside the attentional window. For example, Merikle and Gorewich38 suggested an alternative critical factor –the size of the distractors, or more specifically whether or not they meet the limitations of visual acuity. They presented a color name above and below a central color patch with varying distances: 0.5° or 2.5°. The color names were either incompatible with respect to the color patch  or neutral (a string of the letter ‘l’: “1111”), and they could be small (0.24°) or large (0.57°). Participants had to rapidly identify the color patch while ignoring the color names. The results revealed that when the target-distractors distance was 0.5°, distractor interference emerged for both large and small distractors: RT was significantly slower in the incompatible than neutral condition. However, when the target-distractors distance was 2.5° an interference effect was found only with the large distractors. These findings suggest that the lack of interference effect with the small distractors at the large distance was not necessarily due to the fact that they were presented outside the attentional window. More likely, the lack of effect was due to the fact that at this distance from the center the color names were too small to be resolved, and therefore too small to generate response interference. Likewise, Gatti and Egeth39 employed a similar paradigm and found that the interference generated by incompatible color names decreased as the distance between the color patch and color names increased. This led them to conclude that visual acuity plays an important role in distractor interference, and may compromise measurement of the size of the attentional window. Visual acuity limitations are not a problem in our study because we employed relatively large distractors  and there were four such distractors around the target. Moreover, because our method for measuring the size of the attentional window does not rely on response interference generated by distractors with conflicting semantic meaning, our measurements are not affected by the ability/inability to resolve the distractors’ fine details.A substantial part of our knowledge about spatial covert attention was established in studies that inferred attention allocation based on differences in performance. This is especially so regarding experiments that attempted to measure the size of the attentional window35 concluded that: “…complete elimination of unattended stimuli from semantic processing is a rare occurrence, probably requiring a very special combination of circumstances”. (p. 286). Moreover, Driver and Tipper36 showed that both distractors that generated response interference and those that did not, produced equivalent negative priming, indicating that both interfering and noninterfering distractors were processed and represented. This finding suggests that the presence or absence of distractor interference cannot serve as an indication of attention allocation or processing level (see Fox37 for similar conclusion). The current study overcomes this problem by not relying on differences in performance but on modulations of pupil size. In our study, the disks were neither compatible nor incompatible with the required response, and they were always bright on one side and dark on the other side, so the overall luminance level was always the same and it always affected the PLR. Critically, we tested effects on PLR beyond the overall luminance level – effects that are specific to covert attentional modulations13. If the disks were displayed close enough to the focus of attention so that they fell inside the attentional window  then pupil size was modulated by their brightness. Therefore, the measurement of the PLR seems more informative for our current goal than differences in performance. Additionally, contrary to performance, pupil size does not appear to be under a direct volitional control7 and therefore could serve as an uncontaminated measurement of attentional effects.As mentioned above, even when distractor interference is found, this by itself does not necessarily mean that the distractors were attended, because unattended stimuli are also processed. Indeed, after conducting an impressive serious of experiments that look at different factors that may affect the processing of the distractors, including their distance from the target, Miller26 demonstrated that the characteristics of the attentional window vary as a function of perceptual load; LaBerge1 demonstrated that the size of the attentional window varies as a function of task demands; and a study by Sagi and Julesz31 showed that the size of the window changes as a function of eccentricity. Previous studies who examined the effects of such factors on the size of the attentional window employed only behavioral measurements. Given the limitations of the behavioral measurements detailed above, our understanding of the characteristics of the attentional window would greatly benefit from future studies that will employ the PLR to carefully examine the various factors that mediate the size of the attentional window.Prior research of the attentional window suggests that its size, at a given moment, depends on several different factors. For instance, Caparos and Linnell40 and the attentional attraction field (AAF) model41, a parameter that represents the attentional spread plays an important role. Such models have to ensure that the value they assign to this parameter, when attempting to simulate performance, comply with the minimal size found here. Finally, our findings are important for cross-validation of neurophysiological studies that attempt to examine the characteristics of the attentional window using functional neuroimaging data44.Taken together, this study has important methodological, theoretical and applied implications. In terms of research methods, this study demonstrates the effectiveness of PLR examination as a method to study the nature of spatial attention – a method that is not contaminated by all the above-mentioned factors that are not directly related to attention. Moreover, the results of this study are important for cases in which it is essential to know the exact size of the attentional window in order to ensure that stimuli are falling/not falling within the attentional window. This is critical for the design of experiments that wish to control which information is attended/unattended at any given moment. Additionally, from a more applied point of view, it is also important for the design of optimal visual displays of any form , who wish to minimize clutter. Furthermore, our study has important theoretical implications for the development of physiological and computational models of spatial attention, because the minimal size of the attentional window poses a fundamental constrain on such models. For instance, neurophysiological models of attention have to ensure that the neural substrate suggested to underlie spatial attention can support the minimal size of the attentional window. Similarly, in several computational models, such as the normalization model of attentionTo sum, using the attentional modulation of the PLR we found that the minimal size of the attentional window when attention is narrowly focused has a diameter of about 2°, which is twice the size found when measured based on performance differences.


With the development of carbon nanomaterials in recent years, there has been an explosion of interests in using carbon nanotubes (CNTs) and graphene for developing new biosensors. It is believed that employing CNTs and graphene as sensor components can make sensors more reliable, accurate, and fast due to their remarkable properties. Depending on the types of target molecular, different strategies can be applied to design sensor device. This review article summarized the important progress in developing CNT- and graphene-based electrochemical biosensors, field-effect transistor biosensors, and optical biosensors. Although CNTs and graphene have led to some groundbreaking discoveries, challenges are still remained and the state-of-the-art sensors are far from a practical application. As a conclusion, future effort has to be made through an interdisciplinary platform, including materials science, biology, and electric engineering. A biosensor refers to a sensing device that transfers a biological event to a measurable signal. It usually consists of a biological recognition element and a transducer to translate the biology information to the measurable signal . To be sA great effort has been given in the past few years in the worldwide range on developing novel biosensors with high sensitivity and selectivity. The recent, fast development of nanomaterials has made a profound influence on the development of biosensors. The application of nanomaterials has been given to all technical components of biosensors from recognition components to signal processers. When the material’s size is reduced to nanoscale, the interesting changes in chemical and physical properties are happened due to two principal factors: surface effect and quantum effect. The surface to volume ratio of nanomaterials increases dramatically compared to their bulk form and is able to improve the sensitivity of biosensors through increasing the interface for recognition element allocation. The quantum confinement phenomenon can lead to an increase in the band-gap energy and a blue shift in light emission with decreasing size. As a result, the electrical and optical properties of nanomaterials become size and shape dependent. These essential features of nanomaterials make it possible to turn chemical and physical properties to specific biosensor applications by controlling their size, shape, and chemical composition .The world of nanomaterials is huge and consists of various materials with different nature, size, shape, composition, chemistry, etc. For biosensors, nanomaterials like carbon nanotubes (CNTs) and graphene are popular and at the forefront of the research , 7. Thessp2-hybridized carbon atoms with several nanometers in diameter and many microns in length. There are two classes of CNTs, single walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes (MWNTs). SWNTs can be considered as one rolled-up graphene sheet, while MWNTs are concentric tubes separated by about 0.34 nm of two or more rolled-up graphene sheets. SWNTs have very unique electrical properties, depending on the chirality of the wrap, and they can behave as either metals or semiconductors  and a GOx solution containing CNTs based on an electrostatic layer-by-layer (LBL) technique. It has been observed that the glucose electro-oxidation current increased 6–17 times compared to electrode without SWNTs. The sensitivity of the sensors could be controlled by tuning the number of layers 2+ and secondary antibodies (RuBPY-silica-Ab2) were used as the signal-amplified element. [Ru(bpy)3]2+ labels produce ECL in a multistep electrocatalytic redox reactions with a suitable sacrificial reductant such as tripropylamine (TprA) to yield photoexcited [Ru(bpy)32+]* that emits light at 610 nm. ECL light intensity was integrated by the CCD camera. The detection limit for PSA was 1 pg mL−1 and for IL-6 was 0.25 pg mL−1 in serum. These SWNT forest arrays can be used to interfacing with microfluidic for simultaneous detection of different types of proteins [Electrochemiluminescent (ECL) is a luminescence process that is produced by electrochemical reactions in solution. A CNTs microwell array-based ECL biosensor for detection of cancer biomarkers was developed by Sardesai et al. SWNTs forests were coated onto each of microwells on a pyrolytic graphite (PG) chip. Cancer biomarker prostate-specific antigen capture antibodies  was applied to be covalently attached onto PVP-protected GO for the immobilization of glucose oxidase. Counter anions were allowed to be exchanged with negatively charged GOx. The amperometric response of graphene-GOx-PFIL biosensor is linear against the concentrations of glucose ranging from 2 to 14 mM [−2 M−1 [−2 mM−1) and a detection limit of 64 μM [xOx) on CRGO were reported. The maximum enzyme loadings were found to reach 1.3 and 12 mg mg−1 for HRP and OxOx, respectively. The results indicate that CRGO is a potential promising substrate for efficient enzyme immobilization [As we discussed in the above, CNTs have exhibited excellent performance in enhancing the direct electron transfer between various enzymes and electrodes. The ongoing research shows that graphene-related materials can also promote the electron transfer between enzymes and electrode due to their extraordinary electron transport property and high surface area , 104. Thto 14 mM . Liu et  [−2 M−1 . It has  [−2 M−1 . The layof 64 μM . Zhang elization .4. The prepared rGO-SWCNT-Au nanocomposites were utilized to monitor glucose and revealed a wide linear range and a low detection limit [−1 with a wide linear range up to 18 nM toward glucose oxidation [Besides the graphene-based enzymatic biosensors, the research on graphene-based nonenzymatic biosensors has been carried out worldwide. Wang et al. reported a nonenzymatic glucose biosensor based on Pd nanoparticle-modified graphene oxide (Pd NPs/GO). A linear range of 0.2–10 mM with high selectively was achieved . A novelon limit . Bimetalxidation .−1 cm−2), a wide linear range from 0.4 to 718 µM, and a low detection limit of 25 mM with a fast response time of less than 3 s. The further study in human blood serum was performed, and the proposed FeN NPs/NG core–shell hierarchical nanostructure was found to be a promising candidate for electrochemical biosensor with high sensitivity, excellent selectivity, and good stability [Balamurugan et al. recently reported a novel strategy for the synthesis of an iron nitride nanoparticles/nitrogen-doped graphene (FeN NPs/NG) core–shell hybrid through single-step synthesis method as shown in Scheme tability . A straitability .Scheme 8l-cysteine (Cys) and cross-linker glutaraldehyde (GA). Then, the probe ssDNA was covalently grafted onto the electrode with the presence of GA. The hybridization procedure was monitored by DVP analysis using an electroactive intercalator daunomycin on the electrode. The complementary oligonucleotide could be quantified in a wide range of 1.0 × 10−12 to 1.0 × 10−7 M with a good linearity and a low detection limit of 1.26 × 10−13 M [N-methylpyridinium-4-yl) porphyrin (FeTMPyP) was used to mimic the biological function of HRP. Due to the 2D structure of graphene, FeTMPyP could be attached on the both sides of graphene and led to a high loading amount. They found that this method showed a detection limit down to attomolar levels, much lower than that obtained with a HRP-based trace label [Graphene’s large 2D aromatic surface is an ideal substrate for adsorption of biomolecules as well as a burgeoning support to disperse and stabilize metal, metal oxide, and semiconductor nanomaterials . Similar 10−13 M . Using gce label .Instead of using electroactive indicators or enzyme labels, DNA hybridization can be directly detected through the oxidative signals of DNA bases. As we know, only the adenine (A) and guanine (G) bases give detectable useful signals on traditional carbon electrodes . In the −13 M [Graphene-based DNA impedimetric sensor has also attracted a significant amount of attention due to their advantage of being indicator free. Bonanni et al. have demonstrated a label-free electrochemical impedance DNA biosensor for the detection of DNA hybridization and polymorphism. They also compared the performance of sensors with different graphene layers. Different graphene platforms were modified with hairpin-DNA (hpDNA) probes for the sensitive detection of a single nucleotide polymorphism (SNP) correlated with the development of Alzheimer’s disease. The negatively charged hpDNA probes were immobilized on the graphene and caused an increase in electron transfer resistance. After hybridization with wide type target, the electron transfer resistance decreased due to the partial release of the hpDNA probes from the electrode surface. The less resistance decrease was observed for the hybridization with mutant, and no decrease was observed with the noncomplementary sequence. They also found that sensors with four layers of graphene provided the best sensitivity and were employed for the detection of SNPs. A higher sensitivity was found for as-prepared impedance DNA biosensor compared to that obtained with similar platform using fluorescence methods . In the −13 M .−1 with a detection limit of 0.05 ng mL−1 [As one of the most promising nanomaterials, graphene has been widely used in electrochemical immunosensors. An electrochemical biosensing platform based on graphene for analysis of vascular endothelial growth factor receptor 2 (VEGFR 2) was proposed by Wei et al. In their work, a sandwich-type assay format based on thionine-functionalized chitosan-reduced graphene oxide (CHI-RGO) electrode was developed to detect VEGFR 2 in cell lysates directly. Capture antibodies were grafted onto RGO through the cross-linker GA for the adsorption of VEGFR 2, followed by the immobilization of biotinylated detection antibody. A bioconjugate of antibody and streptavidin-HRP was then used as enzyme labels to provide current signals. The detection limit for VEGFR 2 was found to be 0.28 pM . Liu et  ng mL−1 .−1, and the detection limit is 80 pg mL−1 [−1 to 1 mg mL−1 with a sensitivity of 177.56 Ω cm2 per decade [The label-free graphene-based impedimetric immunosensors have been developed by many researchers. An electrochemical impedance-based biosensor for determination of bovine interleukin-4 (bov-IL-4) was proposed by Chen et al. Reduced graphene oxide (RGO)/chitosan composites were modified on glassy carbon electrode for the attachment of monoclonal bov-IL-4 antibody. The resultant electrochemical impedance is linearly proportional to its logarithmic concentration in the range from 0.1 to 50 ng mL pg mL−1 . Mishra r decade .L-arginine methyl ester (L-NAME) were used as a model drug to stimulate cells to release and inhibit the release of nitric oxide. The nitric oxide concentration is around 350 and 145 nM for 1 and 0.5 mM Ach stimulation, respectively. Since the cell could continue to grow on the biofilm, it was claimed that the method may simultaneously monitor the time-dependent cell density while detecting nitric oxide [Real-time detection of biomolecules released from living cells is significant in the development of applications in clinical diagnosis and drug discovery. Guo et al. reported a biomimetic living cell sensors based on RGD-peptide-functionalized graphene for real-time detection of the biological signaling molecule, nitric oxide. As shown in Fig. ic oxide .Fig. 5a−1 was achieved [−1 or 13 pM) and selectivity toward specific proteins [Recently, much attention has been given to graphene-based FET biosensor due to its high sensitivity to electrical perturbations and high carrier mobility. Ohno et al. reported a label-free immunosensor based on an aptamer-modified graphene field-effect transistor (G-FET) for the electrical detection of IgE protein. The immobilization of IgE aptamers was confirmed by AFM observations. The height of the aptamers is about 3 nm. The aptamer-modified G-FET specifically detected IgE protein . Mao et achieved . In anotproteins . You et proteins .Scheme 92+ (Scheme −1 (three orders lower than the safe blood lead level: 100 μg L−1) was obtained in standard solutions with different Pb2+ concentrations. The proposed aptasensor was further used to detect Pb2+ in real blood sample from children. Their results suggested that such graphene FET aptasensors have great potential for future applications on monitoring of heavy metal ions for health care and diagnosis [Wang et al. proposed a label-free and portable aptasensor based on graphene FET for the detection of child blood lead. Briefly, 8–17 DNAzymes were functionalized on the graphene surface for the capture of Pb+ Scheme . A low diagnosis . The useiagnosis .Scheme 1sp2 carbon clusters embedded within a sp3 matrix and shows light absorption from UV to near-infrared (NIR) regions [π-electrons of GO lead to high fluorescence quenching ability which is very useful in optical-based biosensors [+ and Hg2+), and a small molecule (cysteine) were applied to test the feasibility of simultaneously detecting different targets with this homogeneous ssDNA-GO architecture (Scheme + and cysteine), and P5 (for Hg2+), were assembled onto the GO surface. After the incubation of the target mixture on the modified GO surface, fluorescence emission spectra of the mixture were recorded. One target can induce the disassembly of its corresponding functional ssDNA and result in an increase of fluorescence emission comparable to the fluorescence of the ssDNA-GO architecture. The detection limit was 1, 5, 20, 5.7, and 60 nM for sequence-specific DNA, thrombin, Ag+, Hg2+, and cysteine, respectively [GO has a recombination of electron–hole pairs localized within  regions . The larosensors , 133. Luosensors . Zhang ee Scheme . Differeectively .Scheme 1A fluorescent turn-on sensor for lipopolysaccharide (LPS) detection using peptide-assembled GO was developed by Kim et al. LPS, released from the outer cell membrane of Gram-negative bacteria, is a toxic inflammatory stimulator. In this work, tetramethylrhodamine-labeled LPS-binding peptides were grafted on the GO surface. The fluorescence of the dye-labeled peptide was then quenched due to the interaction with GO. The bond between LPS and LPS-binding peptides led to the release of dye from GO and resulted in the fluorescence recovery Scheme . The detIn order to investigate the sensing capabilities of graphene oxide nanosheets (GO-nS) in living cells, Wang et al. developed an aptamer/graphene oxide nanocomplex for intracellular monitoring and in situ molecular probing. As shown in Scheme 2/Si substrate. Due to the double effect of gold nanoparticles and graphene, the Raman signals of dye were dramatically enhanced. This platform exhibited extraordinarily high sensitivity and a detection limit of 10 pM for DNA. Moreover, it is possible to detect simultaneously more types of target DNAs on the proposed substrate with single-laser excitation [Graphene also can be used as SERS substrate to enhance Raman signals of absorbed biomolecules. He et al. reported a graphene-based SERS platform for multiplex DNA detection. Dye-labeled DNAs were assembled on gold-decorated graphene-SiOcitation .2) and GOx, which further amplified the ECL signal of luminol in the presence of glucose and oxygen. A linear relationship between ECL signals and the concentrations of PSA was obtained in the range from 10 pg mL−1 to 8 ng mL−1. The detection limit of PSA was 8 pg mL−1 [Graphene has been also utilized to fabricate electrogenerated chemiluminescence (ECL) immunosensor. Xu et al. reported a graphene-based sandwich-type ECL biosensor for the detection of cancer marker prostate-specific antigen (PSA). The cathodic ECL behavior of luminol at a positive potential with a strong light emission on a graphene-modified electrode was presented in this work. A signal amplification strategy from enzyme–antibody-conjugated gold nanorods was developed. The graphene–chitosan-modified glassy carbon electrode was prepared for the immobilization of PAS capture antibodies to immobilize PSA. The gold nanorods were used to carry secondary antibody (Ab pg mL−1 .Compared to CNTs, graphene has a much younger history. With the development of graphene in biological and biomedical areas in recent years, a natural question came up is that which one is better for making biosensors. As two popular carbon nanomaterials, CNTs and graphene share some properties in common, including excellent mechanic, electronic, and thermal properties. Graphene can be massively produced at a low cost and does not have metallic impurities which often present in CNTs . GraphenCurrently, it is a worldwide interest in employing carbon nanomaterials like CNTs and graphene in biosensors. It has been demonstrated by researchers that CNTs and graphene can offer new sensing protocols and also improve the detection limit over the existing protocols. The sensors using CNTs and/or graphene are faster in response, cheaper in cost, and smaller in size. However, great challenges remained in biosensors with CNTs and graphene. First, both CNTs and graphene need surface functionalization. The surface properties determine the subsequent performance in sensors. The established chemical approaches for surface functionalization are still far from being applicable and highly reproducible. The reliable and simple methods have to be developed for functionalizing CNTs and graphene in future. Second, biosensors are a class of devices that are able to translate the biological information to other information, like electric and optical signals. The integration of the sensing bed with the signal translator and receiver is another factor determining the efficiency of the sensor. The translation must be fast, reliable, and readable. Third, detecting more than one target molecules is still a great challenge in biosensor development. The medical devices usually require multifunctionality. Fourth, the sensors with strong anti-interference ability are highly desired. The real bioenvironment is much more complicated than the laboratory-built environment. Various biomolecules with similar properties often interfere with the detection of target molecules. To overcome this challenge, the effort must be made on developing highly specific targeting agents and these agents must be robust in various bioenvironments. To solve this problem and to develop CNT and graphene-based biosensors toward a practical application, efforts have to be made in not only materials science and technology, but also electric engineering and medical science.


OBJECTIVES/SPECIFIC AIMS: Emotional processing theory and some observations suggest that activation of subjective and physiological distress during therapeutic exposure and habituation across exposure sessions are key to improvement. This study sought to determine whether initial subjective and physiological activation and between-session habituation would predict PTSD symptom reduction after a series of written trauma narrative exposure sessions. METHODS/STUDY POPULATION: In total, 29 urban-residing African-American participants with PTSD participated in four 30-minute writing sessions. Writing sessions 1 and 2 were 12 hours apart and session 3 and 4 were performed 1 week later, also 12 hours apart. PTSD symptoms were measured at baseline, after session 2, and 1 week after all 4 writing sessions with the Clinician Administered PTSD Scale. During each session, Subjective Units of Distress Scores (SUDS) were assessed 4 times and heart rate was measured continuously. RESULTS/ANTICIPATED RESULTS: Participants exhibited PTSD symptom improvement and habituation of subjective distress, but not physiological arousal, across writing sessions. First session baseline-corrected SUDS maximum and SUDS decrease from the initial to the final writing session were both positively associated with symptom improvement. DISCUSSION/SIGNIFICANCE OF IMPACT: Increased subjective, but not physiological, distress in the first exposure session and diminished subjective distress across sessions may be a helpful marker of emotional processing for clinicians and predictor of symptom improvement after written trauma narrative exposure.


Here we present the longest running time-series of DMS-water (DMSW) concentrations in the world, obtained at the Rothera Time-Series (RaTS) station in Ryder Bay, West Antarctic Peninsula (WAP). We demonstrate the first ever evaluation of interseasonal and interannual variability in DMSW and associated flux to the atmosphere from the Antarctic coastal zone and determine the scale and importance of the region as a significant source of DMS. Impacts of climate modes such as El Niňo/Southern Oscillation are evaluated. Maximum DMSW concentrations occurred annually in January and were primarily associated with sea-ice break-up. These concentrations resulted in extremely high (up to 968 µmol m−2 d−1) DMS flux over short timescales, which are not parameterised in global-scale DMS climatologies. Calculated DMS flux stayed above the aerosol nucleation threshold of 2.5 µmol m−2 d−1 for 60% of the year. Overall, using flux determinations from this study, the total flux of DMS-sulfur from the Austral Polar Province (APLR) was 1.1 Tg sulfur yr−1, more than double the figure suggested by the most recent DMS climatologies.Biogenic dimethylsulfide (DMS) is a significant contributor to sulfur flux from the oceans to the atmosphere, and the most significant source of aerosol non sea-salt sulfate (NSS-SO Approximately 10% of total global DMS production ventilates through the sea-air interface4, where it accounts for approximately 50% of the natural global atmospheric sulfate burden5. Current estimates calculate a global DMS flux to the atmosphere of 28.1 (17.6–34.4) Tg S per year6, which is approximately half the anthropogenic global atmospheric sulfur input7. This makes DMS an important contributor to global sulfur fluxes. Once in the atmosphere, DMS oxidation contributes to the formation of non sea-salt sulfate (NSS-SO42−), a cloud condensation nuclei (CCN) important for cloud formation and thereby reducing incoming solar radiation, and subsequently cooling the climate8. Charlson and co-authors postulated a negative feedback loop between global temperature and DMS production that would keep Earth’s temperature in homeostasis; this hypothesis is referred to as the CLAW-hypothesis. The hypothesis has recently been questioned9 and model calculations on the future response of DMS to changes in global temperature vary widely: both increases11 and decreases12 in surface water DMS concentrations are predicted, with corresponding variation in Southern Ocean DMS flux between the models13. These results indicate large uncertainties in the processes surrounding DMS production, and emphasise the need to generate improved mechanistic understanding so to amend model parameterisation of the DMS flux.Dimethylsulfide (DMS) is a semi-volatile organic sulfur compound produced in surface waters around the globe, primarily from the breakdown of the algal osmolyte dimethylsulfoniopropionate (DMSP)13. The total Southern Ocean (south of 40°S) DMS flux is calculated at approximately 3.4 Tg S during summer months (December to February)14, with an annual total flux estimated at 5.8 Tg S15. However, calculations of the DMS climatologies are still highly uncertain due to two factors. Firstly, the highest DMS concentrations (above 148 nmol L−1), as found in the marginal ice zone, are omitted because data are highly variable and scarce6. Secondly, availability of austral winter data is extremely limited14. A recent update of the summertime climatology, however, indicated that extremely high DMS concentrations might be a real feature in some areas of the Southern Ocean14; in the short, highly productive Antarctic spring and summer seasons, surface water DMS concentrations can exceed 50 nmol L−1 18. These high values are often associated with the release of ice algae, recognised as a significant source of DMSP21, from melted sea ice24. DMSP is an important osmolyte and cryoprotectant and may play a pivotal role in sea-ice algae surviving the extreme conditions of temperature and salinity that prevail in sea ice25. The release of DMSP during ice melt events may be the source of significant input of DMS into polar waters, potentially producing a short-term atmospheric flux of high DMS, although direct evidence for this pathway is limited26. DMS concentrations in Antarctic sea-ice leads have also been found to be an order of magnitude higher than in the underlying water column28.Global climatologies of DMS concentrations show that the polar regions are of significant importance to total global DMS production, in particular the Southern Ocean32. Over the same era, precipitation increased and winds strengthened and veered to be more northerly33. These changes are known not to be monotonic, but to have significant interannual variability superposed34. Whereas the retreat in sea ice will directly impact on the release of DMSP and DMSP-producing algae, changes in the physical environment can also impact indirectly on phytoplankton productivity and composition through changes in light and nutrient availability35.The Western Antarctic Peninsula (WAP) is a climatically very sensitive region. During the second half of the twentieth century, a strong atmospheric warming trend was present, with a marked concurrent retreat in sea ice and warming of the upper ocean38, exceptions being two extensive datasets from the Palmer Long-Term Ecological Research (LTER) program, which show increasing DMS concentrations in December, reaching relatively stable concentrations in January between 5 and 15 nmol L−1 and occasional maxima exceeding 25 nmol L−1 40. To address this knowledge gap, we undertook a five-year study at the WAP that involved measuring water column DMS(P/O) concentrations to identify temporal variability over multiple consecutive years in both winter and summer and to associate these changes with trends in phytoplankton abundance and community composition41. This study was carried out at Rothera Research Station  in Ryder Bay was identified over the five-year time-series ranging between minimum winter temperatures of −1.8 °C and a maximum summer temperature of 3.3 °C in 2012/13 Fig. , decreas−1  remained relatively shallow above 20 m Fig. . Wind at−1 Fig. , with evW in surface waters of Ryder Bay was found to be extremely high, with concentrations exceeding 30 nmol L−1 in four out of five summer seasons and peaking at over 170 nmol L−1 in January 2015  concentrations were distinctly lower than during summer, ranging between 0.1–7.1 nmol L−1  was used with the current RaTS data.With a 5-year averaged wind speed of 12.6 m s−1 Fig. , Ryder BW concentrations . These data were used to generate a year-round climatology of both surface DMSW and DMS flux from Ryder Bay and the wider WAP region. It is estimated that the flux of sulfur in the form of DMS from Ryder Bay was 9.0 Mg S yr−1 (Table −2 d−1) produced during summer and 11% (mean 2.5 ± 5.3 µmol m−2 d−1) during the winter months.During the second, third and fourth years, at least one significant spike in DMS flux was identified each year, where flux exceeded 100 µmol mW and subsequent DMS flux presented here from five years of sampling in Ryder Bay allow us to quantify the interseasonal and interannual variation in DMS emission to the atmosphere from a highly productive region, and evaluate the changes identified with variations in long-term climate trends and shorter-term climate variability, such as the El Niño event that occurred in 2016/17. The results motivate a re-evaluation of existing DMS flux models in the WAP region and have comparable implications for other regions of the Marginal Ice Zone.The DMSW concentrations were generally low in water under the sea ice, due to limited in-situ production from water-column phytoplankton. In winter, mixed layers at the WAP are typically deep (50–150 m) due to buoyancy loss through cooling, brine rejection from ice formation, and mechanical mixing due to wind stress46. These conditions and the low-light levels in winter are unfavourable for phytoplankton growth. During periods of fast-ice cover, water temperature below −1.8 °C and low light penetration, algal communities instead thrive in close association with sea ice, living in the brine channels, porous ice layers and along the ice-sea interface47. Starting in early spring, sea ice retreats southward along the WAP as insolation and temperatures increase. Sea-ice melt together with runoff from land-based glaciers release low salinity water at the surface, resulting in stratification of the upper water column and development of a shallow (<20 m) mixed layer, despite the exposure of the sea surface to wind-driven mixing49. During mid-to-late December, a steady increase of DMSW concentrations developed in all years except in 2016, when ice cover was still 100%.In winter and early spring, DMSW observed during the five years at Ryder Bay in January 2015, Stefels et al.26 calculated similar concentrations as those presented here throughout the wider Marguerite Bay area and further onto the continental shelf and also identified a strong sea-ice influence on surface water DMS(P) concentrations. Occurring in four out of the five years of DMSW analysis, this January peak in DMSW is judged a key part of the annual DMSW cycle, covering a significant percentage of the annual DMSW production in the region. In general, the highest DMSW concentrations were associated with the summer break-up of sea ice, with the majority of high concentrations observed when the area coverage of ice was estimated between 10 and 40%  identified a significant global relationship between DMSW and Chlorophyll a50. Chlorophyll a is determined by fluorimetry as part of the RaTS program, and is used as a proxy for water column primary production in Ryder Bay. No relationship between Chlorophyll a and DMSW could be identified during the five years studied, nor was there a relationship with MLD-normalised chlorophyll a concentration, as also proposed by Simo & Dachs . Further investigation into the relationship between the phytoplankton community structure, other biogeochemical parameters and subsequent DMSP, DMS and DMSO concentrations are currently undertaken51.During the highest peak of DMSW concentrations from Ryder Bay in a wider context, monthly mean DMSW concentrations  than the L11-WAP data (7.8 nmol L−1), which resulted in annual mean surface DMSW concentrations in Ryder Bay higher than the WAP (3.7 nmol L−1 and 2.8 nmol L−1 respectively). When comparing the standard deviations of the data, our data reveal a much higher variation with on average a 43% variation over the year, compared to a 6% variation for the L11-WAP data. This suggests that the L11 climatology is not accurately predicting WAP summer DMSW production, and in particular is missing peak-DMS production events. This motivates improved data coverage along the WAP and further development of long-term DMS monitoring programs in order to further determine the causal factors that drive such peak events.To examine the DMSns Table  were com6. As no attempt was made to quantify DMS flux from sea ice or slush snow layers on top of sea ice, quantification of DMS flux in this study will underestimate the total Antarctic DMS-derived sulfur flux. Gas transfer from the water column can occur through partial ice cover, particularly in coastal environments such as Ryder Bay where movement of ice between the bay and the greater Marguerite Bay area results from wind, water and tidal action. Development of summer shallow MLD upon ice breakup initially suggests limited exchange to the atmosphere of DMSW produced below the immediate surface layers . More specifically, the short-term high-flux peaks in January of each year resulted in flux rates of DMS that exceeded DMSW production, and resulted in the rapid decrease in DMSW concentrations the following day. Interannual variation is especially visible when comparing the 2016–2017 period with previous years, and it is suggested that connections between interannual modes of climate variability (including the El Niño/Southern Oscillation (ENSO) phenomenon and the Southern Annular Mode (SAM)) and the DMS concentrations and flux are present. Firstly, the El Niño event in 2015/2016 coincided with a period of sustained positive SAM and relatively prolonged period of medium-high DMS concentrations during summer. Secondly, an anomalously long period of fast-ice cover in Ryder Bay the following winter, together with a strong increase of SST when ice cover broke-up  conflicts with the rapid retreat of sea ice elsewhere around Antarctica34, but is a known consequence of the directionality of the wind and local topography. The higher SST in Ryder Bay during the summer of 2017  will be the primary source of aerosol particles64. A previous study demonstrated tight coupling between MBL DMS and NSS-SO42−, particularly during periods of intense DMS flux63 such as we identified, suggesting that these spikes in DMS flux will further drive significant production of NSS-SO42- and subsequent particle nucleation. Given that high particle concentrations from nucleation events have been shown to be an important contributor to the global atmospheric aerosol budget64, our data provide evidence that the Antarctic coastal zone particle production has a significant impact on global particle concentrations. Our data also indicates that pulses of DMS flux are an intricate feature of Antarctic coastal areas, which can easily be missed when the frequency of data collection is insufficiently high.The flux values from Ryder Bay exceed those presented from the area of Palmer Research further north on the WAP (~64°S) by at least one order of magnitudeca Table . Of crit26. Therefore, we have used the interannual and interseasonal assessment of DMS flux to calculate the total atmospheric sulfur input from the coastal areas of the WAP and wider Antarctic marginal ice zone  compared to 0.9 million tonnes from the 60–70 °S latitude band (1.9 × 107 km2) as calculated by L116. Normalising for area, a twofold higher sulfur flux was calculated as our annual mean flux compared to L11, showing that the latter is significantly underestimating the Antarctic contribution to atmospheric NSS-SO42− input. In addition, we highlight the south-western side of the WAP as a significant source of sulfur.Given the area and scale of the Antarctic coastal sea-ice zone and APLR, temporal and spatial availability of data on DMS14 utilised a larger DMSW dataset in the Southern Ocean, including a better parameterisation of DMSW and region-specific parameters, to generate a new Southern Ocean DMS summer climatology (J16). During December to February, when our mean DMS flux from Ryder Bay was 30 µmol m−2 d−1, J16 calculated western WAP DMS flux was below 10 µmol m−2 d−1 14. It has been previously discussed26 that the basin-scale methodology used in the J16 climatology does not account for large and dynamic fluctuations in the DMSW concentration and DMS flux shown in the Ryder Bay time series. It is apparent that the important pulses of DMS, leading to potential nucleation events and high particle production, are missed if relatively small data sets are averaged over longer time periods. We show that the data points capped in climatologies should be considered in the model calculations, as these are recurring features of the Antarctic coastal zone. In a global atmospheric circulation model, based on the existing DMS climatologies, it was established that despite variation in spatial and temporal production of DMS, the global mean radiative effect of sulfate is linearly proportional to the global mean surface flux of DMS65. It remains an open question what the radiative effect of the high spikes of DMS and subsequent flux as found in this study will be if incorporated into climate models.Jarníková and Tortell (2016)W concentrations from the longest running time-series studying organic sulfur cycling in the world, and demonstrate the first ever evaluation of interseasonal and interannual variability in DMSW and associated flux from Antarctica. In situ concentrations of DMSW and derived DMS flux were compared to those extracted for the WAP from existing DMS climatologies, and were significantly higher than models predict during January, the most productive time of the annual cycle. Our data also indicate that DMS flux is above the nucleation threshold of 2.5 µmol m−2 d−1 for >60% of the time. Together with extremely high spikes of DMS flux during the Austral summer, this would result in significant production of NSS-SO42− and subsequent particle formation. December was the month of maximum DMS concentrations in the L11-climatology Samples for DMS and physical parameters were collected 2–3 times per week throughout five summer seasons (January 2013 through to March 2017) from the primary Rothera Time Series (RaTS) site at 67.570°S 68.225°W in south-facing Ryder Bay  sensor, was deployed in a single 500 m cast. Data was collected on the down-cast of the instrument, ensuring the shadow of the boat was not interfering with the irradiance data. The surface 1 m measurements were used to determine SST and salinity for flux calculations. The mixed layer depth (MLD) was calculated as the depth at which the density difference relative to the surface is 0.05 kg m−3, consistent with previous RaTS studies48. Full details of RaTS sampling is given in Clarke et al.49. Wind speed at Rothera was obtained from meteorological sensors on station67, and averaged over 24 hours. Sea ice cover in the bay was evaluated visually on a daily basis by observers on station: 100% sea ice cover was characterised by zero visible open water, and zero percent was no visible ice. Sea Ice trends have previously shown good agreement with wider-scale satellite-derived methods48 Fractional ice cover in between the two extremes was comprised of occasional large ice sheets, smaller floes, ice bergs and brash ice. The ice cover would move throughout the bay during the day with wind and water movements.Alongside discrete water sampling, continuous data collection for physico-chemical properties of the RaTS sampling site was undertaken. A Seabird 19+ conductivity, temperature and depth (CTD) instrument, combined with a WetLabs in-line fluorometer for Chlorophyll 13C-DMS was added to each amber sample vial, in order to quantify DMS loss during further processing: 8 mL was taken from the vial and stored in a teflon-stoppered vial for quantification of the total amount of 13C-DMS added. The remaining contents (62 mL) of the amber vial were gravity filtered through a 47 mm Whatmann glass microfiber GF/F filter under dim light conditions, with the process stopped after approximately 20 mL had filtered, prior to the filter being exposed to the atmosphere. Two 8 mL replicates were collected in 20 mL glass, Teflon-stoppered vials for immediate analysis of DMS. DMS was injected into a Proton-Transfer-Reaction Time-Of-Flight mass spectrometer  by purging at a flow rate of 150 ml min−1 through the sample within the vial. A full description of the PTR-TOF-MS method is described elsewhere26. The instrument was calibrated every 10 samples using fresh ~6 µM working DMS standard made in Milli-Q from which ~300 pmol DMS was injected. DMS standards were regularly cross-referenced with deuterated D3-DMSP standards. The instrument has a detection limit of 1–2 pmol. Final DMS concentrations were calculated after correction for the amount of 13C-DMS lost during filtration.Samples were delivered to the laboratory at Rothera within two hours of collection and were stored at 2 °C in the dark. During summer, 50 µL of a known solution of in-situ DMS. Two 70 mL amber glass vials were filled from a Niskin bottle typically collected from 15 m depth, but also from 5 m depth when CTD-fluorescence measurements indicated increased algal biomass. The sample was gravity filtered in a similar way as described for the summer samples. A 10 mL subsample of the filtrate for determination of DMS plus the dissolved DMSP fraction (DMS(P)d) was collected in a 20 mL glass vial, a pellet of NaOH was added and the vial crimp sealed. Samples were stored at −20 °C and analysed during the following summer season. For these winter measurements, the assumption was made that the DMS + DMSPd concentration was the absolute upper limit of potential winter DMS water concentrations and is therefore likely to be an overestimation of DMS. Over the course of the five summer seasons, DMS was on average 2.5 times higher in concentration than DMSPd, suggesting that the inclusion of DMSPd in the winter values will overestimate winter DMS by a mean of 40%. During the winter of 2016, loss of DMS during storage was tested: all samples received an addition of ~200 pmol D3-DMSP standard, before adding the NaOH pellet. Ten individual D3-DMSP working standards were prepared in March 2016, analysed to provide a baseline concentration (t0) and stored in crimp-sealed vials. Every month during winter, a new standard vial was opened for addition to the samples and control samples prepared and stored (t1). Samples from all remaining standards were again prepared upon return to summer-sampling protocol in November 2016 and immediately analysed (tend). This analysis was compared with the t0 and t1 analyses, to quantify loss during use of the standard. All samples collected for DMS(P)d during winter were compared to the t0 and tend standards, and the concentration of each sample adjusted for the percentage recovery of D3-DMS. Mean percentage recovery across the entire winter was 93 ± 14%.During the Austral winter (Apr–Nov) of 2013, 2014 and 2016, water samples were collected and stored for DMS + DMSP , with no direct analysis of Concentrations were averaged over the upper 15 m, with the non-constant depth intervals between samples accounted for in the averaging. This integrated concentration was divided by the depth, to give the mean DMS concentration and was assumed to be the concentration available at the surface for flux. This mean concentration was preferred to a direct measurement of DMS at the surface to remove spatial variability in surface values due to ice cover, and also to provide a best comparison with existing literature. The 15 m cut-off point was selected to provide the best comparison between summer and winter. DMS concentrations for non-sampling days were interpolated from existing values, assuming a linear relationship between concentrations on each sampled day.FDMS) to the atmosphere (µmol m−2 d−1) was calculated for each day, using Equation (W is the concentration of DMS (nmol L−1) and A is the fraction sea-ice cover. Due to the nature of sea-ice, it was expected that even during periods of extreme ice cover, flux would still be occurring through leads and brine channels68, and therefore the minimum open water fraction was set to 0.0169. The scaling of 0.4 allows for the determination of the effect of sea-ice cover on the flux, and is provided by the work of Loose et al. (2009)54. kDMS is the gas transfer velocity (cm−3 hr−1) as based on the model of Nightingale et al.70, according to the method given in Simó and Dachs50:u is the wind speed (m s−1) and Sc is the Schmidt number (cm2 sec −1), which is dependent upon sea surface temperature (t) and salinity as described by the model of Saltzman et al.71:The DMS flux (Supplemental