Further, ZnSk displayed superb antibacterial activity against the tested model gram-negative Escherichia coli bacterium. The produced ZnSk has huge scope to be used for real-world water contaminants remediation applications. We have fabricated ZnO nanoflake structures using degummed silk fibers as templates, via soaking and calcining the silk fibers bearing ZnO nanoparticles at 150 °C for 6 h. The obtained ZnO nanostructures were characterized using scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and UV-vis and fluorescence spectroscopic analysis. The size (~500–700 nm) in length and thicknesses (~60 nm) of ZnO nanoflakes were produced. The catalysis performances of ZnO nanoflakes on silk fibers (ZnSk) via photo-degradation of naphthalene (93% in 256 min), as well as Rose Bengal dye removal (~1.7 mM g ZnO nanoparticles have significant technological applications, as they are well known for their catalytic, electrical, optoelectronic, antimicrobial properties, etc. . They po2, Zirconia, ZnO, hematite, germanium oxide composites, etc. [Hippospongia communis was used to produce TiO2 3D composite structures using hydrothermal conditions (120 °C for 3 h) [Aplysina cauliformis were used to produce novel chitin–GeO2 photoluminescent nanocomposites, using a hydrothermal reaction with a temperature of 185 °C [Sepia officinalis to synthesize a template for the in vitro formation of ZnO nanostructure composites at 70 °C, which are extreme for the used biological material [Taking a practical science point of view into consideration, recent research has been accelerated towards the development of novel composite materials using thermostable biopolymers  and selected inorganic phases ,7. Usinges, etc. ,9,10. Fofor 3 h) . Likewismaterial ,9,10. AmTemplate directed synthesis of ZnO materials is gaining significant interest in research communities, and various porous and non-porous materials of ZnO have been synthesized ,5. PolyeNatural fibers from silkworms are well known for their biomedical applications, and recent studies display their potential as templates for nanoparticle synthesis ,14 DegumE. coli bacteria may be useful for large-scale wastewater treatment applications in real-time settings.Our work focused on introducing a facile template assisted synthesis strategy to attain flake type ZnO nanoparticles. In this study, a green template source (silk fibers) was utilized with zinc acetate precursor, with a reasonably low temperature annealing process, to attain ZnO nanoflakes on silk fibers (ZnSk). The synthesized ZnSk were used for pollutant remediation studies, such as naphthalene degradation and Ross Bengal (RB) dye removal from the aqueous system successfully. The stated chemicals were selected as model pollutants, as they have profound effects on the environment. For instance, the photo-degradation of naphthalene is slow, with photochemical half-life usually beyond 100 h , and RB,Bombyxmori silkworm were gifted by Silkworm Culture and Reeling Unit, Chebrolu, Andhra Pradesh, India. Further degumming steps were adopted from a reported study [2CO3 solution at 100 °C for 30 min. The process was repeated until the silk fibers tuned to white from pale yellow and the degumming solution stayed clear. Next, the samples obtained were washed with deionized water and naturally dried to get degummed silks.Dried cocoons of ed study . In brie3COO)2·2H2O solution was prepared using a mixture of H2O: methanol: ethanol in the volumetric ratio of 5:4:6. A small amount of acetic acid was added to adjust the pH value to ~4.8 to prevent the formation of hydroxides. Then, the solution was homogeneously mixed using a sonicator and 1 mL of it added to degummed silk fibroin of 56.8 mg. The wetted silk fiber was transferred to a glass crucible and kept in an oven at 150 °C for 6 h. The solution without the silk fiber was kept as a control with the above ascribed conditions. The obtained ZnSk structures were further analyzed.ZnO nanostructures were obtained on silk fibers by modifying the approach presented in a reported study using zinc acetate as a starting material . In a tyThe photocatalytic activity of the obtained ZnSk was investigated by means of naphthalene degradation experiment. Primarily, 80 mg of the ZnSk sample  was added to 30 mL naphthalene solution of 43 mg/L in a 100 mL wide mouth glass flask. The investigation was performed at room temperature (34 °C), with continuous stirring (800 rpm) in a rotary shaker incubator. During incubation, the obtained suspensions were irradiated from top under UV lamp (11W), Philips PL-S, Hyderabad, India, a compact UVC source with intensity of 22 lux. Samples for analysis were taken periodically and the decomposition of naphthalene versus irradiation time was monitored by UV–visible spectrophotometer.For reference measurements, silk fibers devoid of ZnO were also exposed to naphthalene, in the same way as the above stated experimental conditions, and monitored spectrally.Adsorption experiments were carried out by maintaining a ratio of RB/(ZnSk or silk fibers) as 2.45 mg/g. An orbital incubator shaker  was used for the study, and samples were monitored till 400 min. A pH of ~6.5 and a temperature of ~34 °C were used for investigations devoid of light. The concentration of residual RB was determined using a UV-visible spectrophotometer , where the measurements were made at 545 nm, which corresponds to its maximum absorbance. Silk fibers devoid of ZnO are used as control. The change in RB dye amounts were calculated from the concentrations in solutions before and after dye adsorption. The mechanism of adsorption by silk and ZnO deposited fibers were estimated by using the pseudo-first and second-order kinetic models . AdditioE. coli, using the zone of inhibition (ZOI) method. Bacterial cell suspension of 0.1 mL (from 2% w/v) was plated uniformly, with the help of spreader on nutrient agar plates. Using a sterile cork borer, 10 mm wells were made on agar plates, and ZnSk composite (of 20 mg) was placed in the well. Here, degummed silk fibers were used as a control and agar plates with samples were then incubated at 37 °C for 24 h. The diameters of the resulting ZOI in mm due to microbial growth were measured using imageJ software on digital images, and the antibacterial activity was determined.The produced ZnSk composite was tested for bactericidal activity against Gram negative UV-visible spectra of the samples were observed using Cyberlab UV100, UV-vis spectrophotometer. The scanning electron microscopy (SEM) observations were performed on JEOL-2100F machine . X-ray diffraction (XRD) measurements were done by X-ray diffractometer , with an accelerating voltage of 35 kV, with a current of 30 mA. The photoluminescence (PL) spectra were measured using spectrofluorometer  of 274 nm is observed, with a decreasing trend in λmax values and up to 93% degradation is observed in 256 min. Silk fibers devoid of ZnO did not displayed any change in λmax value at 274 nm upon UV irradiation, indicating no effect on naphthalene degradation. The prepared ZnSk composites, after repeated use (three times), displayed a decreasing trend of naphthalene absorbance, and the average λmax values at 274 nm with increasing time is shown in Next, we studied degradation study, where 0/C) vs irradiation time, fit better with the first-order kinetic model of the rate law  dose, the degradation behavior of naphthalene is comparable or superior to other reported studies with different nanoparticles (like TiO2) and other approaches [The observed data, in accordance with the ln ZIn addition to the above, complementing our study and observations, the enhanced photocatalytic properties of anisotropic ZnO materials are attributed to the high surface area and the nanofeatures ,34. ThesThe synthesized ZnSk structures have huge scope to be used in real time studies, as they are template based and firmly associated with silk fibers after repeated aqueous washings (observed Zn content is 118 mg/gm ZnSk with net loss in terms of Zn being ~4.8% after 12 washings). The application of ZnSk will prevent the leaching out of ZnO, and these structures can be recovered and reused easily, without any trouble. The consistent degradation ability (>97%) of ZnSk composites after 12 cycles c furtherRB, an anionic dye, was used as a model pollutant to evaluate the adsorption properties of the produced ZnSk composite. As soon as the fibers were exposed to the RB solution, the rose color slowly disappeared, and the typical visible spectrum peak of RB at ~550 nm progressively decreased a. The raTo investigate adsorption controlling mechanism, a pseudo-first order kinetic model was utilized to evaluate the experimental data . The rate (mg/g) is adsorption capacity, qt is adsorption at time t and k1 (min−1), k2 (g mg−1 min−1) are pseudo-first and pseudo-second order rate constants, and h (mg g−1 min−1) is the initial adsorption rate, corresponding to the second-order kinetic model.Furthermore, the pseudo-second order model is presented as follows:2) values for the pseudo-first order kinetics are 0.86 and 0.75 for ZnSk and silk fibers respectively, while R2 values for the second-order model are 0.99 and 0.99 for the same. A better correlation between the modelled and experimental data was observed using the pseudo-second order kinetics model. This favors chemisorption, and this behavior is the rate controlling factor for the adsorption of RB onto silk fibers and ZnSk composite used. The observed performance might be true, as the degummed silk fibers have the ability to fix anionic dyes through ionic bonding. Here, positive –NH2 group of the fiber will bind to acid group of dye [The adsorption kinetics was estimated using Equations (1) and (2) to get information on the adsorption behavior with respect to time. Batch adsorption data using the pseudo-first and second-order kinetic models are presented in p of dye .e is equilibrium dye concentration on adsorbent (mg g−1), Qm is monolayer capacity of the adsorbent (mg g−1), K is adsorption constant (L mg−1), and Ce is equilibrium dye concentration in solution (mg L−1).Furthermore, for examination of the adsorption behavior with different RB dye concentration, a quantitative Langmuir adsorption isotherm model was utilized to evaluate the experimental data. Langmuir equation in its linear form is usually expressed as:e/Qe versus Ce should be a straight line with a slope 1/Qm and intercept 1/QmK.According to the above equation, a plot of Ce/Qe vs. Ce is given in −1), and Qm values are found to be ~1.706 and 0.679 mg g−1 for ZnSk and silk fibers, respectively. The observed Qm values are promising and better than reported values using bottom ash type adsorbents [−1 in the former case, and it is 0.868 mg/g in the later reported study. The reusability of ZnSk composites are tested by exposing them to 0.006 mM RB with a ZnSk dose of 0.287 g in 50 mL solution  for 12 cycles, and results are shown in The equilibrium adsorption isotherm is of primary importance in the design of adsorption process. The Langmuir adsorption model is applied to the experimental data obtained from various RB concentrations and its adsorption a. A plotsorbents  and Fe production, hydrogen peroxide generation, attachment to bacterial cell surfaces, etc. [The antimicrobial activity of as synthesized ZnSk composite was tested on es, etc. ,38,39,40−1 of ZnSk composite material, and the experimental data fitted better to the Langmuir model. In addition to the above, with a potent antimicrobial activity against the tested E. coli at ambient conditions, results suggest that the multifunctional use of the produced ZnSk composites could have huge scope to be used in environmental, industrial, and wastewater treatment applications.In this study, biopolymer, silk fiber was used as a template to synthesize ZnO nanoflakes with zinc acetate as a starting material. This biomimetic approach uses a simple hydrothermal process (with reaction temperature of 150 °C for 6 h) for the growth and formation of ZnO- silk fiber (ZnSk) composites. The ZnSk composite structure was visualized through the electron microscopy, and the results reveal the size of and morphology of the nanoflakes . The deposition of ZnO was confirmed by XRD, SEM, UV, and fluorescence studies. The efficiency of ZnSk composites in naphthalene degradation is demonstrated. The preliminary measurements of the photocatalytic property of ZnSk composites demonstrate more than 97% degradation ability, along with the reusability of the photocatalyst. Furthermore, taking the advantage of ZnSk composite’s anionic dye adsorption capacity, we used RB for adsorption studies. The maximum RB adsorption capacity was found to be ~1.706 mg g


The obtained results reveal that the electronic properties of graphene and MoTe2 layers are well preserved in heterostructures due to the weak van der Waals interlayer interaction, and the Fermi level moves toward the conduction band minimum of MoTe2 layer thus forming an n type Schottky contact at the interface. More interestingly, the Schottky barrier height and contact types in the graphene-MoTe2 heterostructure can be effectively tuned by biaxial strain and external electric field, which can transform the heterostructure from an n type Schottky contact to a p type one or to Ohmic contact. This work provides a deeper insight look for tuning the contact types and effective strategies to design high performance MoTe2-based Schottky electronic nanodevices.Two-dimensional (2D) transition metal dichalcogenides with intrinsically passivated surfaces are promising candidates for ultrathin optoelectronic devices that their performance is strongly affected by the contact with the metallic electrodes. Herein, first-principle calculations are used to construct and investigate the electronic and interfacial properties of 2D MoTe Two-dimensional 2D) layered crystals have attracted increasing interest due to their novel physical properties and potential applications in various fields since the discovery of graphene . UnconveD layered2 includes three interesting phases: hexagonal  phase [d, type II Weyl semimetal) phase [2 has an indirect band gap of about 1.0 eV for bulk and a direct band gap of about 1.1 eV for monolayer [2 is simply referred as MoTe2. Compared with other TMDs, MoTe2 has many advantages, for example, the conductivity is lower [2 and graphene, fabricating a type of heterostructure by graphene and MoTe2 for device applications could be considered. Actually, recently vertical heterostructures based on 2D-layered-structure materials have been attracted increasing interests [2, some experiments have investigated the graphene-MoTe2 heterostructure [2. It was reported [2 vertical heterostructure is as high as ~(0.5 − 1) × 10−5, and the photo responsivity can reach 20 mAW−1, which are comparable to the corresponding values of graphene-MoS2 device. Later, based on graphene-MoTe2-graphene vertical vdW heterostructure, a near-infrared photodetector was fabricated [2 vdW vertical transistor which exhibits suitable V-shaped ambipolar characteristics [2 heterostructures are promising candidates for optoelectronic nanodevices with high responsivity, high-speed, and flexible. In this sense, it is essential to carry out a theoretical investigation on graphene-MoTe2 vertical heterostructure which has not been reported yet.As a member of TMDs, bulk MoTeg) phase , monoclig) phase , and octl) phase , 21, in onolayer , 23, whiis lower , Seebeckis lower , and theis lower , 25. Comnterests –33 due tnterests –38, as ctructure –43 due treported  that thebricated , 42 witheristics  was repoFor the metal-semiconductor heterostructure, the contact type (Schottky contact or Ohmic contact) has to be considered, because it determines the existence of rectifying characteristics or not for the heterostructure. For the Schottky contact, the Schottky barrier height (SBH) would play a key role on the behaviors of the corresponding devices  and has 2 heterostructure have been investigated. The calculated results demonstrate that the electronic properties of graphene and MoTe2 monolayer are preserved quite well after being vertically stacked up as a heterostructure. The Schottky barrier of the heterostructure can be changed between p type and n type by applying an external electric field or strain, and the heterostructure can even reach the Ohmic contact when the external electric field or strain is strong enough.In this paper, based on first-principles calculations, electronic structure, and external electronic field and strain dependence of the SBH of graphene-MoTe−6 eV for energy and 0.01 eV/Å for force. The Brillouin zone k-point mesh is set as 9 × 9 × 1 within the Monkhost-Pack scheme. A vacuum space of 25 Å along the z direction is adopted to avoid the interaction between the neighboring layers. As it was revealed that the spin-orbit coupling effect on band structures of 2H-MoTe2 is very weak [First-principle calculations have been carried out using the Vienna Ab-initio Simulation Package (VASP) –47 basedery weak , all of 2 heterostructure is constructed by graphene and MoTe2 monolayer via stacking the two 2D materials along the vertical direction. Both graphene and MoTe2 adopt the hexagonal lattice and their lattice parameters are 2.46 Å [2 monolayer, here, three typical stacking modes are considered: HS-1, HS-2, and HS-3, which are shown in Fig. The graphene-MoTee 2.46 Å  and 3.52e 2.46 Å , respectWhen the strain dependence of the SBH is investigated, strain is applied equally along the zigzag and armchair directions of graphene, respectively.2 monolayer and three typical stacking modes  of the graphene-MoTe2 heterostructure have all been fully optimized. The obtained binding energies of the three typical stacking modes are all nearly the same, i.e., −0.85 eV, while the equilibrium interlayer distances of the three modes are all approximately equal to 3.53 Å. Hence, we solely focus on the HS-1 graphene-MoTe2 heterostructure for the following discussion and omit “HS-1” for simplicity in the following text. The optimized geometry structures of MoTe2 monolayer and graphene-MoTe2 heterostructure are shown in Fig. 2 monolayer adopts the hexagonal lattice and the optimized lattice constant is 3.52 Å, which is consistent with the experiment results [2 monolayer, as it is shown in Fig. 2 monolayer is a semiconductor with a band gap of 1.14 eV, which is also consistent with the experiment results [2 monolayer are vertically stacked up as a heterostructure, the equilibrium interlayer distance is 3.53 Å, which is comparable to the value of the Sb-MoTe2 heterostructure (about 3.94 Å) [2 layer and graphene layer in the graphene-MoTe2 heterostructure almost remain the same as the original structures of MoTe2 monolayer and graphene, which indicates the interaction between these two layers is weak. The binding energy of equilibrium structures −0.85 eV is lower than that of the Sb-MoTe2 heterostructure (about −0.37 eV) [2 and graphene is weak vdW type.The lattice crystal structures for MoTe results . It can  results , 23. Whe 3.94 Å) . It coul0.37 eV) , so the 0.37 eV) , graphen0.37 eV) , graphen0.37 eV) , and gra0.37 eV) , indicat2 monolayer are stacked up to form the heterostructure. The 3D charge density difference in the graphene-MoTe2 heterostructure defined as Δρ = ρH − ρG − ρMT has been calculated, where ρH, ρG, and ρMT are the charge densities of heterostructure, isolated graphene, and MoTe2 monolayer, respectively. The result is shown in Fig. 2 layer, which indicates that the electrons accumulate around the MoTe2 layer; while graphene layer is surrounded by the dark pink area, implying that the holes accumulate around the graphene layer. To see the property of the charge transfer more clearly, the planar average 〈∆ρ〉, which is defined as the average value of the 3D charge density difference Δρ in planes with z = const. that are parallel to the graphene layer, is shown as a blue line in Fig. 2 layer, and there are oscillations in 〈∆ρ〉 in both the graphene and MoTe2 layer. The electron localization function (ELF) is also plotted in Fig. Actually, the charge redistribution and transfer would inevitably occur when graphene and MoTe2 heterostructure are shown in Fig. 2 layer demonstrate that the semiconductor characteristics of MoTe2 layer with a direct band gap are retained. The band gap of MoTe2 layer is 0.85 eV in the heterostructure, which is changed compared with the result of 1.14 eV for the isolated MoTe2 monolayer. One striking feature in Fig. 2 layer is insufficient to modify the characteristics of the band structure of each component in the heterostructure, so the interlayer interaction effect on the band structure is very weak. This further indicates that the vdW interaction dominates between MoTe2 layer and graphene layer in the heterostructure, and thus preserving the intrinsic key properties.Many physical properties are determined by the band structures and density of states (DOS), and the calculated band structures and DOS of the graphene-MoTe2 heterojunction-based transistor has been designed, and the schematic diagram is shown in Fig. 2 monolayer is used as the channel material and graphene as both source or drain and gate electrodes. Due to the difference in work functions of the metal and semiconductor, there is a band bending at the interface, which can be estimated by the Fermi level difference (ΔEF), defined by ΔEF = WG − MT − WMT, where WG − MT and WMT are the work functions of the heterostructures and the corresponding MoTe2 monolayer, respectively. The calculated WG − MT and WMT are 4.36 eV and 4.84 eV, respectively, as is shown in Fig. EF) is about 0.48 eV in the heterostructure, which is comparable to the result of graphene-hydrogenated phosphorus carbide heterostructure [The contact properties of heterostructures are of importance for device applications. A graphene-MoTetructure .Fig. 6a2 layer), which determines the current flow across the interface of heterostructures thus playing a significant role in the corresponding device performance. In general, according to the types of the semiconductors in heterostructures, SBH is divided into n type and p type, respectively. The n type SBH (ΦBn) is defined as the energy difference between the conduction band minimum (CBM) of the semiconductor (EC) and the Fermi level of the metal (EF), i.e., ΦBn = EC − EF. The p type SBH (ΦBp) is defined as the energy difference between the Fermi level of the metal and the valence band maximum (VBM) of the semiconductor (EV), i.e., ΦBp = EF − EV. The SBH results of the graphene-MoTe2 heterostructure is shown in Fig. 2 monolayer to conduction band side of MoTe2 layer in the heterostructure, which denotes that the SBH of the heterostructure is n type with the value of about 0.33 eV at the interface. That is to say, the charge conduction of the heterostructure will be mainly through electrons.One of the most important contact properties of metal-semiconductor heterostructures is Schottky barrier at the vertical interface  of the MoTe2 layer almost remains constant under the external electric field, which denotes that the external field has little effect on the pristine electronic properties. This can be understood as follows: although the external electric field can change the energy eigenvalues of the valence electron such as CBM and VBM, their relative values are unchanged, resulting in the band gap remaining constant. In other words, the external electric field could not change the band structure except the band bending. It can be also seen clearly from Fig. 2 without any barrier, indicating that MoTe2 possesses a metallic conductivity, and thus realizing a Schottky-to-Ohmic contact transition. For the negative electric field when the intensity exceeds 1.0 V/nm, the heterostructure could also be tuned to the Ohmic contact. All these results demonstrate that applying an external electric field is an effective strategy to modulate the SBH and contact type for the graphene-MoTe2 heterostructure.To improve the performance of heterostructure-based transistors, it would be desirable to tune the SBH. It is demonstrated that the SBH can be tuned via applying an external electric field and in-plane strain , 30, 58.z coordinate of the Te atoms are relaxed while the positions of other atoms remain fixed after changing the size of the unit cell. It is shown that strain can also tune the SBH of the heterostructure between n type and p type and drive the heterostructure to approach the Ohmic contact. The behaviors of strain dependence of SBH are very different with that of the electric field dependence. The situation becomes much more complex. For a wide strain range, ΦBn is smaller than ΦBp, while only in a narrow tensile strain range ΦBp maintains smaller than ΦBn. That is to say, the strain range of n-type SBH (the strain is about −10 ~ 4%) is much wider than that of the p type (about 4 ~ 7%). When the tensile strain reaches 7% and the compressive strain reaches 10%, the Ohmic contact for the heterostructure also appears. It is worth noting that the band gap of the MoTe2 layer in the heterostructure would change strongly with the variation of the strain in the Schottky contact region, which is strongly different with the results of the electric field case. When the lattices are under strain, they would deviate from the equilibrium state, thus causing the change of the band structure. In fact, not only the value of band gap but also the type of band gap (direct or indirect) would be change by strain. For small strain, MoTe2 layer remains a direct band gap while it changes to indirect band gap for large strain. Here, it should be pointed out that for a real transistor the actual conditions to realize the Schottky-to-Ohmic contact transition may be somewhat different with the calculated results due to the actual situations.The SBH as a function of the in-plane biaxial strain is also calculated and the results are displayed in Fig. 2 heterostructure, which is indispensable to design 2D vdW heterostructure based field-effect transistors. Furthermore, the graphene-MoTe2 heterostructure can be applied for tunable Schottky diodes in nanoelectronic and optoelectronic devices.The above results suggest that both applying an external electric field and in-plane biaxial strain are effective methods to control SBH and the type of contact of the graphene-MoTe2 heterostructure under different electric fields and biaxial strains have been systematically investigated based on first-principle calculations. The electronic structures of graphene and MoTe2 are well preserved after being stacked up together along the vertical direction, which suggests that the interlayer interaction of the heterostructure belongs to the vdW type. However, the Fermi level moves toward CBM of the MoTe2 layer after the formation of the heterostructure, i.e., the Schottky contacts are n type with a 0.33 eV SBH. The SBH and the type of contacts at the heterostructure interface can be effectively modulated by applying an external electric field or strain. When an electric field is applied, in the Schottky contact region, the n type SBH exhibits an approximately upward linear relationship with the electric field, and p type SBH behaves reversely. The heterostructure can be tuned to the Ohmic contact for an electric field which is greater than 1.0 V/nm at both positive and negative sides. For the case of applying biaxial strain, the situation is more complex than the electric field case. The strain range of n type SBH is much wider than that of the p type. When the tensile strain reaches 7% or the compressive strain reaches 10%, the Ohmic contact also appears. All the results demonstrate that applying an electric field or strain is a good way to control of the SBH as well as the type of contact of the heterostructure, even drive the system into the Ohmic contact. These features are quite significant for designing high performance nanoelectronic and optoelectronic devices.In summary, the band structures of the graphene-MoTe


Since its discovery, graphene and its multiple derivatives have been extensively used in many fields and with different applications, even in biomedicine. Numerous efforts have been made to elucidate the potential toxicity derived from their use, giving rise to an adequate number of publications with varied results. On this basis, the study of the reproductive function constitutes a good tool to evaluate not only the toxic effects derived from the use of these materials directly on the individual, but also the potential toxicity passed on to the offspring. By providing a detailed scientometric analysis, the present review provides an updated overview gathering all the research studies focused on the use of graphene and graphene-based materials in the reproductive field, highlighting the consequences and effects reported to date from experiments performed in vivo and in vitro and in different animal species . Special attention is given to the oxidized form of graphene, graphene oxide, which has been recently investigated for its ability to increase the in vitro fertilization outcomes. Thus, the potential use of graphene oxide against infertility is hypothesized here, probably by engineering the spermatozoa and thus manipulating them in a safer and more efficient way. Leafing through the newspapers or magazines, listening to the radio, looking at the television or surfing the Web it is impossible to do not stumble on news regarding the use of graphene in everyday life, from the formulation of new batteries  and the Graphene is chemically defined as a two-dimensional material or, more impressively, a one-atom thick species formed exclusively of carbon atoms packed in a honeycomb crystal lattice ,6,7. DesThe spreading of graphene and, overall, its oxidized derivatives into the biomedical research world  has led The present review is aimed to outline all the research studies focused on the use of graphene and graphene-based materials in the reproductive field, highlighting the consequences and effects reported by the scientific community during the last years. As a first step, a detailed scientometric analysis will be presented, created after analysing the published literature regarding the interaction between graphene and Graphene-Derived Materials (GDMs) and the reproductive function in animal models and humans, with the aim of evidencing the research efforts made on that issue.Then, particular attention will be directed to the recognition of the various derivatives belonging to the family of graphene-based materials investigated in these researches, with special attention to the oxidized form of graphene, GO. The idea is to follow the classification created by Wick et al. in order to understand structure–activity relationships in the context of health science and safety and to avoid generalizations of the term graphene . In addiA detailed bibliographic search was carried out to create a data set for the scientometric analysis, made up with the Advanced Search Function of Web of Science Database (WoS) .For the present analysis the topic “graphene” was used in combination with “sperm”, “spermatozoa”, “human spermatozoa”, “oocytes”, “reproduction”, “fertility” and “human fertility”. As a result, 29 documents  were found published from 2012 to 2019 see . Since dIt is evident from the analysis performed that the number of research products is recently increasing , as well as the number of citations , even ifTo explore the most relevant issues related to the scientific production in the selected products, the International Scientific Indexing (ISI) keywords were analysed. The words most commonly used inferred from the analysis were: “toxicity” (11), “in-vitro” (8), “nanoparticles” (8), “carbon nanotubes” (7) and “graphene oxide” (6). Moreover, the thematic map showed that “graphene oxide” and “in vitro” are of great importance in the research field studied. Regarding the most relevant source, the analysis showed that the majority of the manuscripts were published in journals included in the Web of Sciences Category (WC-Subject Area) “toxicology”, while only one article was published in a journal within the category “reproduction”.The analysis of the contribution from each country is an interesting tool to evaluate the scientific production. Researchers from China, Italy and Korea represent the most active countries in these topics, representing the 60% of the total of publications. On the other hand, the analysis of the collaborations evidences the absence of strong collaborations among researchers from different countries, with no multiple interactions. The analysis of the network with the dynamics of authors and co-authorships establishes that there are many sub-networks, with all the components characterized by the tendency to form highly clustered structures that do not communicate with each other. Taken together, these data suggest that the scientific community is highly fragmented, highlighting the lack of communication among scientists. Cytoscape Software  was used to integrate and analyse the networks . SupplemMany methods of preparation have been developed in order to obtain graphene, but they differ in the final size, quality and production costs. In general terms, graphene can be obtained following two different strategies: the top down and the bottom-up. Most mass scale graphene is produced by a top-down approach via graphite exfoliation. This process consists of the peeling off of graphene from graphite, requiring large amounts of solvent and mechanical mixing, sonication or electrochemical treatment ,32,33,34On the other hand stands the bottom-up synthesis of high quality graphene, exploiting chemical vapor deposition or advanced organic synthetic methods that allows to recover very small amounts of the final material and at very high costs ,40.In the present analysis of research studies evidencing the effects of graphene and graphene derivatives on reproductive functions, the biggest problem that came to light, as mentioned above, was the nature and features of the investigated materials. As a matter of fact, the term graphene was often used as a general term to indicate carbon materials spanning from zero-dimensional carbon materials such as carbon black (CB)  and nanoIn order to shed light and clarify the different materials investigated and generically referred to as graphene or carbon materials, the following is a list of the most representative materials that have been encountered during the present bibliographic analysis.D/IG, index of occurred oxidation, is 1.55.Pristine and acid purified SWCNT, differing for their metal (iron) content  and oxidGraphene nanoplatelets or graphene nanoparticles (GNP) in their pristine version ,49 or fuDespite the reduced molecular weight of such material, only a few studies reported detailed properties and dimensions of GQDs, although bottom up and top-down approaches of synthesis could entail completely different products. For example, whereas a commercial sample was described only in terms of round shape of 40–45 nm size and X-ray diffraction pattern , other sThese particles are a variant of pure carbon quantum dots that contain also nitrogen and oxygen. They are prepared by different methods: solvothermal approach in DMF using GO as a precursor  or pyrol4/NaNO3 and H2SO4 [2sp carbon atoms and oxygen-functionalized regions containing moieties such as hydroxyl (–OH) and epoxide (–O–) functional groups on the two accessible sides, and carboxylic acid (–COOH) or carbonylic (C=O) groups at the edges. It is a hydrophilic derivative of graphene and possesses different degrees of oxidation depending on the precise protocol of preparation [w/w, that may vary from 0.25 [Graphene Oxide (GO) is typically produced, as reported above, by a Hummer’s method  or slighnd H2SO4 . The proparation . The graparation . Researcparation ,56,57,58paration , oxygen rom 0.25  to 0.39 rom 0.25  or as firom 0.25  or >36% rom 0.25 ), dimensrom 0.25  to 3–5 µrom 0.25 ,47), surrom 0.25  to −56.7rom 0.25 ). In a from 0.25 ,63 or arrom 0.25  sheets wrom 0.25  or harshAll materials obtained by reaction of GO with different agents can be inserted in this class. For instance, carboxylic GO (GO-COOH) can be obtained through oxidization on GO surface of epoxy and hydroxyl groups to carboxyl groups by performing chemical modification with sodium chloroacetate . Within 3sp carbon atoms, missing in pure graphene. rGO can be obtained following different approaches. The widely used reductive agent is hydrazine [This compound is a reduced version of graphene oxide, often named as pristine graphene due to the fact that, theoretically and as reported above, the reduction in oxygenated moieties of GO should bring graphene oxygen to its original progenitor, graphene. Obviously, this is not perfectly true and rGO keeps numerous defects and ydrazine ,57,66 buIn recent years, the spread of graphene-derived materials has caused many researchers concern regarding the environmental and health impacts derived from their use, giving rise to different manuscript publications.As has been inferred from the scientometric analysis, the majority of the studies conducted to date regarding graphene and GDMs and reproduction have aimed to analyse the toxicological events involving the reproductive function, a powerful approach that allows examining not only the detrimental effects caused to the single individual but also the effects left in bequest to the offspring. In that way and from 2014 see , some reOther researchers, by contrast, have carried out their experiments in different animal species and either in vivo or in vitro by analysing the health of the offspring after exposing the forefathers with different graphene derivatives and concentrations, as it will be further reviewed  to mammals .Caenorhabditis elegans and paracentrotus lividusCaenorhabditis elegans (C. elegans) is one of the most common species used to study the toxicological phenomena derived from the use of non-physiological compounds, thanks to its relatively short life, low cost, well-known genetic background and easy handling. In this regard, various graphene-derived compounds at specific concentrations have been added by some research groups to the soil living-medium, showing low or no toxicity [The soil nematode hermaphrodite toxicity ,49,52 ortoxicity ,71. For toxicity . It is wZhao et al. investigated a completely different material, nitrogen-doped GQDs characterized by the presence of both nitrogen and oxygen moieties and by a really small size . They were used to evaluate the potential toxic effects at different concentrations . Authors demonstrated the absence of toxicity for the nematodes, targeted organs and embryos .2 (amide) and COOH (carboxylate) at various concentrations  for 72 h. In this case, GO and GNP were precisely characterized, being essentially micrometric flakes, not necessarily single layer. Their findings, based on the number of offspring at all stages beyond the egg, showed some toxic effects varying with the graphene type, surface functionalization, number of layers, dose and time exposure, with no toxicity for the lowest concentrations (5 and 10 µg/mL). In a later work, they further investigated and compared the effects of few-layered nano-sized GO and rGO at doses of 20, 50 and 100 µg/mL for 72 h, demonstrating a higher reproductive toxicity of GO than rGO, likely due to the activation of a non-canonical Wnt-MAPK signaling cascade as the possible underlying mechanism causing the GO reduced reproductive capability [On the other hand, Chatterjee and co-workers have found some negative effects in the reproductive potential of the worms influenced by the surface functionalization and layer number of the different graphene materials utilized . Concretpability .The toxicity caused directly to the reproductive organs (concretely the gonads) has been also evaluated. Zhao and collaborators added GO at different doses  to the worms’ living medium until their young adults stage. In this case, GO was synthesized from graphite and had a size of 40–50 nm, prevailingly monolayered. They found that concentrations of GO 10–100 µg/mL induced the production of more germ cell corpses (thus inducing germ line apoptosis) as well as a slightly decreased brood size and number of oocytes, an inhibition of the egg injection rate and an increased embryo mortality. Moreover, they suggested an epigenetic protection mechanism probably activated by GO, hypothesizing a novel self-protection mechanism against toxicity .After long-term GO exposure  of young adult nematode, GO-characteristic Raman spectral bands measured throughout the bodies of C. elegans revealed the accumulation of GO in the reproductive organs, a reduced sperm number and a damage of the spermatogenesis . AdditioParacentrotus lividus) has been also used by researchers to study the sperm toxicity after the exposure to commercial graphene materials, such as carbon black (CB) and GO. As far as GO is concerned, it was prevailingly mono-layered with a mean size ranging between 0.5–5.0 µm and containing 20% by weight of oxygen. Their findings showed that, after 1 h of sperm exposure to different concentrations , egg fertilization was significantly affected with a reduction of around 50% in the case of CB or had almost no effect in the case of GO [The Mediterranean purple sea urchin  to evaluate the effects of commercial GO and rGO at concentrations of 250 and 1000 mg/Kg of dry soil. By evaluating the life cycle of the soil, the Authors confirmed reduced hatching, survival and reproduction rates after the treatment with the highest concentrations and in a dose-dependent way [Spodoptera frugiperda (S. frugiperda) by Martins et al. at different doses . Both monodimensional and bidimensional carbon nanomaterials affected the reproductive performance when they were used at the highest concentrations, which could entail ecologic and economic consequences for the agriculture sciences [Similar experiments were performed with the soil invertebrate dent way  for the sciences .Mouse2+, to analyse GO biodistribution. Male mice were exposed to this compound by oral gavage  or IV injection  to study the short and long-term reproductive ability. Their results illustrated that the exposed mouse possessed normal sexual behaviours with no affectation of the testes and epididymis, normal pregnancy rates and litters, and a normal development and growth of the offspring. GQD-exposed mouse sperm retained high quality, suggesting that GODs avoided to penetrate the blood-brain and blood-testis barriers [Mouse species is commonly used for the study of reproduction, since mice are cheap, easy to maintain and straightforward to breed in captivity . Additiobarriers . On the barriers . NeverthAkhavan et al. performed a work in which they confirmed the uptake of NGO sheets by the testis of male mice after IV injecting the compound to both female and male mice in vivo every week for 8 weeks at concentrations of 2, 20, 200 and 2000 µg/mL (last one corresponds to 4 mg/kg mouse). They used GO nanosheets  obtained by oxidation and sonication from GO. They analysed the spermatozoa, finding a reduced viability, motility and progressive motility and a decrease in some kinetic parameters, as well as a higher reactive oxygen species (ROS) production and DNA fragmentation when exposed to the highest NGO concentrations. In addition, they reported for the female mice a decreased fertility, gestation rates and hormone concentrations  when using the highest concentrations of this graphene material .125I, whose stability is known to be not very good for long-term tracking [Similar nanoGO samples were used by Liang and co-workers to perform their experiments, but results were completely different from the previous study. Concretely, they used two sizes of NGO previously used for cancer phototherapy and in vivo tumour targeting ,75  intraperitoneally injected at doses of 0.4, 2 and 10 mg/kg for 7, 15 or 30 days . Their findings demonstrated a dose-dependent reduction in the number of spermatozoa, spermatogonia and spermatids, a decreased sperm motility, and some morphological abnormalities in the groups that were treated with the highest NGO concentrations. Moreover, some oxidative stress was confirmed with the increased activity of antioxidant enzymes, without causing damage to the testis or reducing the fertility potential, data confirmed with the healthy offspring derived from the matching with female rats .The study of the toxicological effects in vivo provides an interesting amount of information about the general and systemic effects, as well as the evaluation of many vital functions, organs and tissues as a whole. However, this model poses an important problem, since it acts as a black box: it is possible to know the details about the input  but not the output . Moreover, it is of great importance to consider the neurohormonal control of reproduction, involving a network of central and peripheral signals in the hypothalamic-pituitary-gonadal axis . Due to To our knowledge, only one research work has been published to date regarding the toxicity of graphene on the female germ cell, the oocyte. Lin et al. recently incubated in vitro GDQs with mouse oocytes at doses of 0.5, 1 and 1.5 µg/mL. By evaluating the oocyte maturation at different times, they found an interference in the maturation process, with no appreciable toxicity regarding the development of the offspring in vivo . FurtherRegarding the toxicity of the graphene materials in vitro caused to the male germ cells, a modest number of articles have been published to date. Asghar and co-workers functionalized carbon nanotubes (SWCNT-COOH) and rGO to evaluate their influence on human spermatozoa when incubated with different concentrations  over 30 min and 3 h. The Authors found an absence of toxicity on sperm viability and kinetic parameters, but an increase in ROS production when using SWCNTs-COOH, supporting the possibility to develop microfluidic sorting systems to select the sperm subpopulations .2H4-GO), reduced by hydrothermal reaction (HT-GO), and with green tea polyphenols (GTPs-GO). After incubating for 2 h with different doses , they found a reduced viability, motility and progressive motility whereas some kinetic parameters, for concentrations >1 µg/mL, were influenced in a dose-dependent manner. Moreover, all the compounds but the GTPs-GO increase the ROS and nitric oxide (NO) production, while decreasing the ATP and NAD+/NADH [Hashemi and co-workers found some cyto- and genotoxic effects in mice spermatozoa when exposed to GO and various rGO: GO reduced with hydrazine , most oIn order to confirm the positive results obtained in the IVF assays in a different animal model and in more physiological conditions, further experiments were carried out using a bovine in vitro model in which a somatic component, the oviductal epithelial cells, was included. This innovative model allowed us to verify the absence of toxicity when spermatozoa were capacitated in the presence of GO 1 µg/mL, to confirm the positive effects in terms of IVF outcomes, and even more important to evidence the absence of toxicity during the early embryo development (until Day 8 post-fertilization). Furthermore, the increase in the bull sperm fluidity was confirmed, giving rise to an interesting number of proteins and lipids modified after the treatment with the GO solution .Very recently, our group moved forward towards the use of the mouse model, currently used for the study of most of human diseases since mice and humans share virtually the same set of genes  . The resAs has been exposed, the vast majority of the works published to date related to graphene and reproduction are focused on the study of the toxicological events that this fusion entails. However, the first approach of what might be the first steps into the bioengineering of the male gametes to minimize the problem of infertility has also been presented, a worldwide issue that affects around the 20% of couples in the world (48.5 million) and entails psychological, social, demographic and financial problems for the society. It is known that the male factor is responsible for around the 50% of the cases, and among them, the 30% are due to unknown causes ,86,87. Thttps://www.grandviewresearch.com/press-release/global-assisted-reproductive-technology-market) “the global assisted reproductive technology (ART) market is expected to reach USD 45.4 billion by 2025, according to a new report by Grand View Research, Inc. Childbearing postponement is one of the high impact rendering drivers of the infertility treatment market. The reproductive behavior and pattern of some of the nations such as few European nations have shifted from early to late childbearing pattern. Increasing marital age, rising tobacco and alcohol consumption, increasing obesity rate are some of the other factors contributing to the market growth. Furthermore, increasing incidence rate of conditions such as poly-cystic ovarian syndrome (PCOS), tubal factors and endometriosis are other drivers of the market”.It is important to mind that, as reported by the Grand View Research Incorporation (Archea to mammals, including Human, has been provided here. What is emerging is a very interesting perspective presenting two sides of the same coin: on the one hand they could be harmful materials, with possible toxic effects on such delicate and important function; on the other hand, it is possible to speculate that the GRMs, and GO in particular, could represent a possible way to fight the problem of infertility by manipulating spermatozoa in a safer and better way.In summary, an updated overview of the scientific literature concerning graphene and graphene-related materials and reproduction in several organisms, from


Since the success of monolayer graphene exfoliation, two-dimensional (2D) materials have been extensively studied due to their unique structures and unprecedented properties. Among these fascinating studies, the most predominant focus has been on their atomic structures, defects, and mechanical behaviors and properties, which serve as the basis for the practical applications of 2D materials. In this review, we first highlight the atomic structures of various 2D materials and the structural and energy features of some common defects. We then summarize the recent advances made in experimental, computational, and theoretical studies on the mechanical properties and behaviors of 2D materials. We mainly emphasized the underlying deformation and fracture mechanisms and the influences of various defects on mechanical behaviors and properties, which boost the emergence and development of topological design and defect engineering. We also further introduce the piezoelectric and flexoelectric behaviors of specific 2D materials to address the coupling between mechanical and electronic properties in 2D materials and the interactions between 2D crystals and substrates or between different 2D monolayers in heterostructures. Finally, we provide a perspective and outlook for future studies on the mechanical behaviors and properties of 2D materials. For MThe common types of 2D oxides include lead, phosphorus, and transition metal oxides a–d 82,8,882,83. The imperfections introduced during production processes inevitably distort the pristine lattices and have a significant influence on the mechanical properties of materials. The accurate manipulation of defects has been recognized as an effective approach to alter/modify the mechanical properties of materials. Structural defects in 2D materials have attracted much attention since the era of graphene has arisen. In particular, design based on topological defects in 2D materials has become a hot topic in the field of mechanics and material sciences ,86. HoweAs shown in 1 (5-9) defect), and one dangling bond [2 (5-8-5) defect] arrangement, with a formation energy of 8.7 eV . . 2, but nalities . The GBsGB kinks c,d [107,GB kinks b and hasn the GB .2 mentioned above, the formation energies of vacancies in phosphorene are much lower, which is attributed to the weaker P–P bond and the puckered structure [Noncarbon 2D materials with a single element have also attracted tremendous attention due to their unique structures and distinct properties. The phosphorus monolayer exfoliated recently exhibited fascinating electronic properties for future applications ,113,114.tructure .2 molecule first dissociates and then reacts with P atoms in phosphorene [Interstitial defects usually appear during the growth of 2D phosphorus sheets. The self-interstitial P atom prefers to form two bonds with P atoms in different layers, leaving one dangling bond . As a resphorene ,119. FirAlthough there are many allotropes for boron, the boron monolayer on the silver surface under ultrahigh vacuum conditions was successfully synthesized in 2015 . Boropenv) have been recently discovered from both theoretical predictions [v1/9 structure is predicted to be the most stable [Unlike other 2D crystals, multiple polymorphs of borophene with different arrangements of periodic hexagonal holes  found in borophene structures have similar lattices and can serve as the building blocks of a number of borophene crystalline phases by controlling the mixing ratio of the two rows  nanoindentation by Lee et al. . As showe strips ,133,134.e strips . Table 12 and graphene nanoribbons [2 is consistent with that from DFT calculations, while the measured strength varies within a large range. Such considerable variation is attributed to undetectable pre-existing cracks introduced during the synthesis process [Although AFM nanoindentation has been widely adopted to measure the elastic properties and strength of 2D materials, it induces highly localized stress and strain underneath the AFM tip, which to some extent affects the strength measurement. A nanodevice was recently developed to achieve uniform tensile stress and used for mechanical testing of MoSeoribbons . The obt process . Current2 [2 are isotropic, as indicated by Atomistic simulation is an increasingly powerful tool for investigating the mechanical properties of nanostructured materials . As an a2 . As an iTo describe the elastic properties of 2D materials, a molecular mechanics model and molecular structural mechanics model have been developed as a bridge to link atomic structures with macroscopic properties. Aiming at the linear elastic properties (such as Young’s modulus and Poisson’s ratio), Chang and Gao first adopted an effective stick-spiral model and derived analytical expressions to describe the elastic moduli of graphene and carbon nanotubes . Beyond Defects have a significant influence on the mechanical properties of 2D materials. Even the mechanical properties of 2D materials can be tuned by controlling the density or distribution of defects. As mentioned above, vacancies are one of the most common structural defects in 2D materials. Interestingly, a controlled density of vacancies introduced in graphene by irradiation can significantly increase the Young’s modulus up to 550 N/m . This phSingle crystalline graphene is usually obtained from mechanical exfoliation and has a limited in-plane length scale. In recent years, the chemical vapor deposition (CVD) growth approach has been used as a main synthesis method for the large-scale production of graphene. However, the CVD-grown graphene involves some GBs. Understanding the GB effects on the mechanical properties is essential for the applications of graphene. Recent nanoindentation tests have confirmed that the Young’s modulus and strength of CVD-grown high-quality graphene are comparable to pristine graphene . NotablyThe size effects of strength have been widely investigated in various nanostructured materials, for example, the classic Hall–Petch relationship in polycrystalline metals. Analogously, substantial attention has also been drawn to polycrystalline graphene ,179,180.The MD simulations mentioned above have revealed that nanocrystalline failure during tension typically initiates at GB junctions. The grain size effect of the strength largely depends on the detailed microstructures of the GBs. To date, nearly all present studies on the mechanical properties of polycrystalline materials are based on MD simulations, but physically realistic GB arrangements might have a certain discrepancy with the constructed samples used in modeling. Therefore, real experiments are still needed to investigate the relationship between polycrystalline graphene strength and grain size. Theoretical models of realistic GB structures are also required to further study the mechanical properties and behaviors of polycrystalline graphene.2 [The theoretical strength describes the maximum stress that can be sustained by perfect materials, while the fracture toughness is a measure of the material’s resistance to crack prorogation. Since crack-like flaws are inevitably introduced to 2D materials during synthesis or transfer, the fracture toughness of 2D is essential for practical applications of 2D materials . Recentl2 , which i2 ,184. The2 . The cra2 ,186. MD 2 . Such a 2 .2, respectively [The fracture behaviors and properties of polycrystalline graphene have been recently investigated via in situ experiments and atomistic simulations ,182,188.ectively ,182,188.ectively ,188. As ectively . Such inectively . The cri2 have shown that MoS2 has a much lower critical stress intensity factor than graphene [2 is dependent on the orientation. Furthermore, the crack edge chirality is found to determine the crack propagation path because of the more complex atomic arrangement of MoS2. The zigzag crack prefers a straight path, while the armchair crack extends via a kink, leaving a zigzag edge [2. However, MoSe2 is too brittle to sustain precracks through FIB cutting, resulting in a catastrophic failure during the cutting process. The lower surface energy of MoSe2 further suggests that MoSe2 is a more brittle material than graphene [With the bursting of various 2D materials, their fracture behaviors have drawn increasing attention. MD simulations of the fracture of perfect MoSgraphene . Similarzag edge . For phozag edge . Due to zag edge . The samgraphene .It is a long-standing challenge in the field of material science to achieve a material with both high strength and high fracture toughness. As a representative 2D material, although pristine graphene has very high stiffness and strength, it possesses a rather low fracture toughness. As crack-like flaws are inevitable in graphene, an effective toughening strategy is required to improve graphene’s toughness and ensure its safety and reliability during applications. The introduction of controlled topological defects has been proven to be an effective solution to toughness enhancement. It has been demonstrated that topological defects (such as disclinations and dislocations) give rise to apparent out-of-plane wrinkling, which can be utilized to generate 3D graphene structures and further alter the fracture properties . Using t2 kirigami structure [Another promising toughening method utilizes the interaction between nanocracks, i.e., establishing the concept of kirigami design. Recent MD simulations showed that patterning graphene with cuts results in a significant increase in yield and fracture strains ,198. Thetructure . As a retructure ,201,202.tructure . Recentltructure . Althougtructure , kirigamNanocomposites are also a significant toughening strategy for 2D materials. One-dimensional carbon nanotubes (CNTs) are embedded in graphene to construct a hybrid structure, figuratively called “rebar-graphene.” Rebar graphene is demonstrated to remarkably enhance the fracture toughness of pristine graphene h,i. Such2 also suffers out-of-plane ripples when subjected to shear loading. In particular, under the mixed mode of modes I and II, buckling cracks are generated due to out-of-plane deformation [The 2D materials exhibit other fracture modes (such as shear and tear failure) except mode I fracture. Due to the single-atom-layer structure, graphene under shear exhibits out-of-plane wrinkles, further affecting the in-plane mechanical properties. MD simulations have shown a reduction in fracture strength due to shear-induced ripples . The forormation . The proormation .Tearing is also a significant fracture mode that occurs during the fabrication and applications of 2D materials . Moura a9 cycles at an average stress of 71 GPa and a stress range of 5.6 GPa [Recently, Cui et al. used AFM to investigate the fatigue behaviors of graphene and graphene oxide . It was  5.6 GPa . These f 5.6 GPa . Cui et  5.6 GPa . The fat 5.6 GPa . These s2 monolayer, oscillating piezoelectric outputs were detected under cyclic loadings  is considered an ideal candidate because of its natural presence of triangular nanopores [3N4 to be piezoelectric. More importantly, such piezoelectricity does not vanish in structures with multilayers, which is convenient for its fabrication and applications [Another intriguing approach to create in-plane flexoelectricity is the introduction of noncentrosymmetric nanopores. Tight-binding modeling and DFT calculations have been adopted to investigate graphene monolayers containing triangular or trapezoidal pores g 236,23. Due to anopores . Both DFications .Bulk materials with laminate structures are widely used as solid lubricants because of interlayer weak bonding by van der Waals forces. The high relative surface area and good thermal properties of 2D materials make them ideal candidates for lubricants in nanoscale electronic or mechanical systems . The AFMThe friction measurements via frictional force microscopy (FFM) of the chemically modified graphite showed an unexpected increase with decreasing normal load, indicating a negative friction coefficient . The cor2D materials generally exist in the forms of single layers, few layers, or multiple layers. It is necessary to investigate the interlayer shearing and sliding of 2D materials to further explore their assembly and to ensure their performance and reliability during applications. When two graphite sheets are in incommensurate contact, they can easily slide with each other, exhibiting superlubricity due to the ultralow shear strength between two graphite sheets . Such suThe defects of 2D materials alter the surface states of the structure, leading to apparent modifications of their friction behaviors. FFM measurements showed that charged iron irradiation-induced defects in single-layer graphene efficiently enhanced friction . MD simuA wide range of applications of graphene results in complicated environmental exposure. When exposed to humid conditions, graphene was observed to present increased friction compared with that in a dry atmosphere, which becomes more apparent with aging. Experiments and simulations have indicated that increasing friction is associated with variations in surface energy . FurtherWhen 2D materials are attached to substrates, the interaction strength between these systems has proven to be a determinant of their friction behaviors . ModificThe booming study of 2D materials has attracted much attention beyond the simple structures and properties of graphene and its analogs. Indeed, the interactions between 2D materials and substrates and between heterogeneous multilayers have attracted enormous interest due to their distinct properties and exciting applications.Strain engineering of 2D materials has brought a new dawn of fundamental mechanisms and thrilling applications. Graphene, although it exhibits extraordinary electronic properties, lacks a band gap, making it intricate in practical applications. Various approaches have been proposed to modify the band gap in graphene to broaden its applications, among which the mechanical strain method has drawn much attention. First-principle calculations have indicated that the opening of the band gap is expected through asymmetrical strain. When uniaxial tension is applied to graphene, a tunable band gap of graphene can be achieved, but the symmetrical biaxial strain has a negligible influence on the band gap opening ,259. The2 under uniaxial strain have been indirectly observed [Due to the atomic nature of 2D materials, precise strain control over monolayer or few-layer structures remains challenging. Currently, the strain engineering of 2D materials can be achieved by epitaxial growth, thermal strain, and flexible substrates . The epiobserved ,264. The2-supported graphene presents pronounced weakened carrier mobility, which results from the surface roughness and interlayer contamination. Graphene laid on a single crystalline h-BN has demonstrated a remarkable enhancement in carrier mobility compared with that on SiO2 substrates [2 sandwiched with graphene may enlighten further development [The evolution of research on graphene and isolated 2D crystals has shifted focus to atomic layers vertically stacked by different 2D materials. Van der Waals-bonded heterostructures are emerging with unique structural and electronic varieties, resulting in their possible applications in novel electronic and photoelectronic devices ,266. Silbstrates . This substrates . The hetbstrates . The comelopment .2/MoSe2 [2/WSe2 [The tunable electronic and optoelectronic properties of heterostructures can be achieved through the crystallographic orientation between stacking crystals. For the graphene on the h-BN substrate, the similar hexagonal structure with a 1.8% difference in lattice constant results in a moiré structure when joining. The induced periodic potential forms a secondary Dirac point . Rotatio2/MoSe2  and MoS2 [2/WSe2 . However [2/WSe2 ,275. Des [2/WSe2 ,275.In this review, we summarize recent advances in experimental, computational, and theoretical studies on the mechanical behaviors and properties of various 2D materials, including their tension and fracture behaviors, piezoelectricity, flexoelectricity, friction, interlayer shear properties, and van der Waals interactions. We further emphasize that some common defects in 2D materials have a profound influence on their mechanical behaviors, suggesting tunable properties by defect engineering. Although graphene discovery has stimulated prosperous studies of 2D materials, there are still open questions calling for further exploration.2, or h-BN monolayers, while experiments have seldom been conducted for other newly synthesized 2D crystals due to technological limitations and difficulties. The extraordinary properties of novel 2D crystals largely remain as theoretical proposals. In addition, the experimental approach is quite limited for mechanical measurements of 2D materials. The pioneering work of nanoindentation tests for graphene has become the most frequent mechanical characterization approach for 2D materials. However, nanoindentation induces local deformation and only reveals an average property for anisotropic 2D materials. A more effective analytical model is needed for extracting the intrinsic mechanical properties of 2D materials [Numerous experimental characterizations and mechanical tests have been mainly performed on graphene, MoSaterials ,277. ForThe defect engineering or topological design of 2D materials has drawn much attention for tunable mechanical or electronic properties, but there is a general lack of fundamental understanding of intrinsic mechanisms for defective structures. For the mechanical strength, the disagreement of various defects’ influences calls for experimental verifications and further theoretical explanations. The toughening of brittle 2D crystals has been realized via topological design. It is then necessary to further probe the optimization of fracture properties by controlling patterned defects, which may be a heavy burden due to variant design parameters. Further explorations of tailoring fracture behaviors rely mostly on understanding toughening mechanisms and interactions between cracks and defects, which until now remain mysterious. Although the introduction of patterned defects into pristine 2D crystals has been given by previous studies ,279, theInvestigations on 2D materials have extended from specific performances to taking them as platforms for heterostructure studies. In addition, unstable 2D structures require encapsulation by other 2D materials with chemical inertness for practical applications. The typical assembly process of heterostructures contains the layer-by-layer transfer of monolayer 2D crystals. This procedure has high inefficiency, which urges the further development of assembly techniques. The effort of epitaxial growth on other 2D materials as templates endows the possibility of large-scale synthesis for industrial applications ,281. RecA new era of nanotechnology has been seen since the first discovery of graphene monolayers. After extensive efforts in the scientific community, 2D materials have been revealed as marvelous candidates for many applications, from conventional mechanics, electronics, and optics to novel biomedicine, drug delivery, and energy storage. The emergence of vertically stacking heterostructures has broadened the studies of 2D materials beyond monolayer crystals to multilayer structures by human design. An expanding number of family members and defect engineering methods further provide multiple choices for tailoring the mechanical, physical, and chemical properties of 2D material systems, which can be used for future practical applications.


We review the evidence for bio-regulation by coral reefs of local climate through stress-induced emissions of aerosol precursors, such as dimethylsulfide. This is an issue that goes to the core of the coral ecosystem’s ability to maintain homeostasis in the face of increasing climate change impacts and other anthropogenic pressures. We examine this through an analysis of data on aerosol emissions by corals of the Great Barrier Reef, Australia. We focus on the relationship with local stressors, such as surface irradiance levels and sea surface temperature, both before and after notable coral bleaching events. We conclude that coral reefs may be able to regulate their exposure to environmental stressors through modification of the optical properties of the atmosphere, however this ability may be impaired as climate change intensifies. Coral reefs cover some 600,000 square kilometers of the earth’s surface (0.17% of the ocean surface), with coral ecosystems amongst the most diverse on the planet . Coral rOn many reefs, reduced stocks of herbivorous fishes together with increased sediment and nutrient loading from land-based activities  have cauSince the late 20th century coral reefs have been subjected to a new range of environmental threats associated with climate change that can seriously jeopardize their continued existence unless radical change occurs in the governance and management of reef systems . These tInterestingly, reduced incoming light due to cloudy conditions has been shown to mitigate bleaching in the Pacific . Coral rOver the past 10–15 years, field and laboratory studies have provided evidence for the existence of a hitherto unrecognized climate bio-regulation process in coral reefs . This isOur understanding of aerosol-climate interactions although growing, is still incomplete, being identified by the Intergovernmental Panel on Climate Change (IPCC) as one of the key sources of uncertainty in our knowledge of Earth’s energy budget and anthropogenic climate forcing . This isThe quite separate fields of coralline ecology and aerosol-climate interactions both have a long and rich history. Unsurprisingly however, given the distinct disciplines involved, the intersection of these fields is relatively recent. Indeed, most of the published research on biogenic aerosol emissions by coral reefs has appeared in the last two decades. Notwithstanding the emerging nature of the field, there are numerous aspects of the topic that bridge the disciplines of climatology, aerosol science and coral reef ecology. Consequently, we have chosen to employ an integrative or critical review approach. Our aim is to assess the current evidence for coral reef bio-regulation of climate and to synthesize the literature in a way that will enable a new theoretical framework and paradigm to emerge , 2016. LAerosols are minute solid or liquid particles suspended in the atmosphere and are derived from a variety of natural and anthropogenic sources, ranging from industrial processes, volcanic eruptions, biomass burning and marine ecological processes. Aerosol particles are either emitted directly to the atmosphere (primary aerosols) or produced in the atmosphere from precursor gases (secondary aerosol). All atmospheric aerosols scatter incoming solar radiation, and a few aerosol types  can also absorb solar radiation. Aerosols that mainly scatter solar radiation have a cooling effect, by enhancing the total reflected solar radiation from the Earth . HoweverThe most convincing evidence for aerosol modulation of cloud properties has been seen in the marine atmosphere , specifiThe effect of an change in atmospheric aerosol concentrations on the distribution and radiative properties of Earth’s clouds is the most uncertain component in model projections of the global radiative forcing of climate . This maThe role of natural aerosol emissions in cloud radiative forcing is less certain but thought to be even greater than that due to anthropogenic aerosol . With reSymbiodinium (Symbiodinium) is to some degree involved in the synthesis and cycling of these sulfur compounds , a central molecule in the marine sulfur cycle and precursor of DMS . Both DMiodinium  and coraiodinium  which, tiodinium . It has ompounds .Acropora corals  was noted some decades ago in the Florida keys, where extremely high concentrations of atmospheric DMS were observed after aerial exposure of the reef at low tide , and lata corals , the domc stress . Seasonac stress . If aeric stress . Corals c stress .Notwithstanding the recent progress in the field, there is limited understanding of the mechanisms of DMS production by the coral holobiont and relatively sparse data on either dissolved or atmospheric DMS concentrations in coral reef areas. Similarly, estimates of DMS fluxes to the atmosphere from reefal environments are as yet poorly constrained and not included in global DMS data bases such as that of Although the nexus between MBA emissions and changes in the properties of maritime clouds has been debated for a long time , signifiIn pristine coral reefs such as the WPWP, DMS emissions are thought to be the key driver behind an ocean thermostat which suppresses ocean warming below coral thermal tolerance thresholds (~30 °C) through a build-up of low-level clouds (LLC), as shown in An 18-year time series study  of satelAcropora spp. are the dominant coral genus throughout the GBR and Indo-Pacific and are strong producers of climatically active dimethylated sulfur compounds (2) are estimated to emit 20 Gg S year−1 as DMS  See . The Greompounds . The GBR1 as DMS  and may a) also occur when the coral reef is aerially exposed at low tide  and dry, mild winters (May–October). Corals upregulate the biosynthesis of DMSP and catabolism to DMS during physiological stress caused by exposure to elevated SST and solar irradiance, or due to low salinity associated with seasonal rainfall and riverine discharge . These plow tide , with attide  are also capable of producing high concentrations of DMSP  biosynthesis increases with thermal and irradiance stress, followed by oxidation by ROS to DMSO in temperature-sensitive species. These species are the dominant reef-building corals in the GBR and are the strongest individual producers of DMS(P) . The rat of DMSP  and may  of DMSP . HoweverAcropora spp. favor Clade D endosymbionts when exposed to thermal stress (The ability of corals to adapt to the rapidly changing climate will govern changes to DMS emissions from the GBR. Corals have a close association with a range of microbes and therefore harbor a diverse genome  that mayl stress , which cl stress . This mal stress . Rapid rl stress . Temperal stress , althougl stress  and willBiogenic emissions of DMS are a significant source of atmospheric sulfur, which in remote marine environments, are an important source of secondary sulfate aerosols. These non-sea salt sulfates play a significant role in the local climate of these remote marine environments, yet emissions of natural aerosols and their precursors remain one of the largest contributors to our uncertainty in aerosol radiative forcing , and ultPristine coral reef dense regions such as the GBR, are particularly strong sources of atmospheric DMS, similar in magnitude to highly productive high-latitude oceans. Corals upregulate the biosynthesis of DMSP and catabolism to DMS in response to physiological stress, with both processes important in maintaining coral homeostasis and promoting resilience to rising ocean temperatures. It is hypothesized that coral reef emissions of DMS increase the formation and condensational growth of marine aerosols and CCN, thereby increasing the brightness, lifetime and cover of low-level marine clouds. Local cloud cover is an important determinant of the spatial extent and severity of coral physiological stress and coral bleaching. Thus, enhanced MBA emissions and LLC cover may establish a negative feedback over coral reefs to mitigate coral physiological stress.−1 emitted from the 3,000 individual coral reefs and surrounding lagoon waters significantly influences aerosol and cloud properties in north-eastern Australia. However, there remains substantial uncertainty surrounding the importance of DMS emissions in the properties of the local atmosphere above coral reefs, and what implications ongoing coral reef degradation may have on these complex biogeochemical processes.This review has discussed evidence of significant links between coral physiological stress, DMS emissions, aerosol loading and local cloud cover over coral reefs, highlighted by a case study on the GBR, Australia. Given the vast size and relatively remote, pristine location of the GBR, it is possible that the 20 GgSyrThe current rate of ocean warming and coral reef degradation increases the urgency at which we must improve our understanding of the importance of DMS in the coral reef radiative climate. Non-linear changes in DMS emissions have been reported in response to thermal and light stress in corals . HoweverIt is possible that rising ocean temperatures will lead to an increase in DMS emissions from coral reefs, although as indicated above, there are limits on the DMS increase associated with the onset of bleaching . This poThe predicted increase in the frequency and severity of mass coral bleaching events may require the implementation of biological and/or physical interventional management strategies. The propagation of temperature-tolerant coral species may allow coral reefs to recover from recent bleaching events . PhysicaThere is enormous incentive to improve our understanding of the drivers of coral resilience, including the role of dimethylated sulfur compounds in alleviating oxidative stress and influencing the radiative balance. Future research needs to focus on the quantification and characterization of the flux of these compounds from coral reefs and its influence on aerosol and cloud formation. An improved understanding of these biogeophysical processes will provide insight into how to enhance the natural defense mechanisms of corals and inform climate engineering proposals, which may need to be implemented as a last resort to conserve coral reefs in the face of ongoing climate change.


At the regional scale, DMS emissions increase atmospheric sulfur dioxide (SO2) and sulfate 2 and 3) in the air of Shanghai by 1.5%~2.5%. DMS emissions increase fine-mode ammonium particle concentration distribution by 4% and 5%, and fine-mode nss-Marine biogenic dimethyl sulfide (DMS) is an important natural source of sulfur in the atmosphere, which may play an important role in air quality. In this study, the WRF-CMAQ model is employed to assess the impact of DMS on the atmospheric environment at the regional scale of eastern coastal China and urban scale of Shanghai in 2017. A national scale database of DMS concentration in seawater is established based on the historical DMS measurements in the Yellow Sea, the Bohai Sea and the East China Sea in different seasons during 2009~2017. Results indicate that the sea-to-air emission flux of DMS varies greatly in different seasons, with the highest in summer, followed by spring and autumn, and the lowest in winter. The annual DMS emissions from the Yellow Sea, the Bohai Sea and the East China Sea are 0.008, 0.059, and 0.15 Tg S a Dimethylsulfide (DMS: CH3SCH3) is the most abundant volatile biogenic sulfide emanating from the ocean [The global emissions and environmental effects of biogenic sulfur have become increasingly important with the decline of anthropogenic sulfur dioxide  and wind speed –18. The e et al. . Bates ee et al. ,20 pointd Nguyen  reporteda et al.  reportedl et al.  reportedhina Sea –26. Yanghina Sea  estimate3) to directly produce SO2 and methanesulfonic acid (MSA), while ignoring the contribution of halogen to DMS oxidation [2 concentration over many sea areas increased by more than 40 parts per trillion by volume (pptv), and the annual average concentration of 3. Due to the high DMS emissions and high oxidant concentration, DMS showed the greatest impact in summer with the average concentration of 2 , and NO3) and the composition and mass of fine particles. Although the concentration of ozone (O3), NO3, and HOx decreased, the average concentration of secondary organic aerosol (SOA) increased by 10%. Perraud et al. [2 emissions are reduced to zero. In China, DMS-related studies generally focused on field observation. There have been few reports on the impact of DMS in China seawater on the regional and urban atmospheric environment using numerical modeling.Numerical modeling plays an important role in studying the impact of DMS on regional and urban atmospheric environments. Large-scale atmospheric chemistry models usually contain very simplified DMS chemistry, including the oxidation of DMS by hydroxyl radical (OH), nitrate , chlorine radical (Cl), chlorine monoxide (ClO) and iodine monoxide (IO). The detailed reactions are provided in The US EPA’s CMAQ modeling system version 5.2 was used in this study. The CMAQ v5.2 model was configured to utilize the CB05 gas phase chemistry mechanism together with halogen chemistry (cb05eh51) ,37. DMS High-resolution simulations were performed for three nested model domains on a Lambert conic conformal projection . The out2.2.2.5, PMcoarse, SO2, NH3, NOx, BC, OC, CO, CO2, and VOC). The terrestrial anthropogenic emissions inventory in the Yangtze River Delta in 2017 was provided by the Shanghai Academy of Environmental Sciences (SAES) at a 4 km × 4 km resolution and included nine pollutants . Since DMS is a marine biogenic sulfur gas, in addition to the above land-based emission inventories, anthropogenic emissions, especially anthropogenic sulfur emissions over the ocean areas are also of great importance. The shipping emissions were then constructed using o model developed by Fan et al. [2 emissions generated by human activities in January, April, July, and October were 2.3 Tg, 1.6 Tg, 1.8 Tg and 1.8 Tg, respectively, among which shipping emissions accounted for 46 Gig, 56 Gg, 63 Gg, and 62 Gg, respectively. Marine emissions of halogen species include two inorganic iodine species (HOI and I2) and nine halocarbons . The details of halogen emissions have been described elsewhere [In this study, anthropogenic emissions for the outermost domain were obtained from the Multi-Resolution Emission Inventory for China (MEIC v1.3) developed by Tsinghua University and MIX inventory developed by the Model Inter-Comparison Study for Asia (MICS-Asia III) and Hemispheric Transport of Air Pollution (HTAP) for other areas. The most recent emission inventory data is 2016 for MEIC and 2010 for MIX , which cn et al.  based onn et al. . The comlsewhere ,37.2.3.For model studies, the concentration data of DMS in seawater from the Global Surface Seawater DMS Database are generally used. The spatial and temporal distribution of DMS concentration in seawater from this global database are shown in 2.4.T [w is the concentration of DMS in seawater. Cg s the concentration of DMS in air, H is Henry’s law coefficient. The DMS concentration in seawater is about three orders of magnitude higher than that in air, so the Cg × H term can generally be ignored. The total gas transmission rate kT can be further obtained by the water side transmission rate (kw) and atmospheric gradient fraction (γa) [Ocean-atmosphere DMS fluxes are computed as the product of the concentration gradient between air and water (Δc) and the total gas transport resistance at the air/ocean interface  :(2)kT=kka can be calculated according to Kondo [10 is 10-meter wind speed, MDMS and MH2O are the molecular weights of DMS and water, respectively. It is the parameterization of kw that the largest uncertainty in DMS emission flux comes from. In this study, the Liss and Merlivat, 1986 (LM86) [kw) transfer velocity:cDMS is the Schmidt number of DMS related to the sea surface temperature SST (T/°C) [The air side transmission rate to Kondo :(4)ka=66 (LM86)  parameteT (T/°C) :(6)ScDM3.3.1.2 and PM2.5 (fine particles) concentrations from nine eastern coastal cities . The statistical metrics of normalized mean bias (NMB), root mean-square error (RMSE) and correlation coefficient (r) are calculated to quantify the degree of deviation between the observed data and simulated results, as shown in 2 and PM2.5 concentrations are underestimated by small margins with NMB in the range of −33.36% to −9.66% and −13.50% to +12.18%, respectively. Compared to those without DMS emissions, the model with DMS emissions increases SO2 concentrations and improves the comparison with observed data by small margins (<3.2%) at all cities. The addition of DMS emissions have a mixed impact on model performance for PM2.5. The model without DMS emissions already overpredicts PM2.5 at Zhoushan, Ningbo, Qinhuangdao and the addition of DMS emissions marginally deteriorates the comparison with observed data. In other cities, the model with DMS emissions improves the comparison with observed PM2.5 concentrations by small margins. The deviations between the simulation and observation occur due to the uncertainties of meteorological fields, emission inventories, chemical mechanisms, and deposition.Model performance for the regional domain is evaluated by comparing model predictions with observations of atmospheric SO2, NO2, PM2.5, and O3) are provided by the Shanghai Pudong Monitoring Station. The temporal variations of observed and predicted concentrations in January, April, July, and October in 2017 are shown in 2 is lowest (7.74%) at the Lingang Station, the NMB for NO2 is lowest (10.49%) at the Pudong Monitoring Station, the NMB for O3 is lowest (−20.60%) at the Pudong Monitoring Station, and the NMB for PM2.5 is lowest (−8.11%) at the Lingang station. The predicted O3 concentrations are underestimated with NMB ranging between −20.6% to −39.6%. However, the model can reasonably reproduce the observed spatial and temporal trends of these pollutants.For the innermost Shanghai domain, model predictions with DMS emissions are compared with observed data from three monitoring stations , Zhoupu Station , and Lingang Station ). The monitoring stations are located at distances of 5–22 km from the coast. The observed data of four major atmospheric pollutants , the Yellow Sea  and the East China Sea , the annual DMS emissions of the Bohai Sea, the Yellow Sea, and the East China Sea are 0.008, 0.059, and 0.15 Tg S a−1, respectively, which is slightly higher than the estimates of 0.074 Tg S a−1 in the Yellow Sea and East China Sea by Yang et al. [Based on the simulation results of four typical months, the annual average emission fluxes of DMS calculated by the LM86 method in the Bohai Sea, the Yellow Sea, and the East China Sea are 5.1, 6.9 and 8.8 μmol mg et al.  using thAccounting for only a small proportion of the global ocean, the Bohai Sea, the Yellow Sea, and the East China Sea are typical continental shelf areas in the world, where the emission flux of DMS is, however, far larger than that of the remote seas in all seasons. The contribution of DMS release from the continental shelf areas is not negligible, which is also consistent with the previous research results ,59.3.3.In this study, the localized database and the LM86 method are used to simulate the concentration of pollutants in the atmosphere in the four typical months. The impact of DMS emissions on the atmospheric environment in the eastern coastal region of China is examined by comparing the results with those obtained without DMS emissions.3.3.1.2, 2 concentration in four typical months. The addition of DMS emissions effectively increases SO2 levels in the atmosphere in all seasons. Higher enhancements are predicted over seawater than over coastal areas. In terms of seasons, DMS shows the highest contribution to regional atmospheric SO2concentration in summer, especially in the Bohai Sea and the East China Sea with a maximum of 0.63 μg/m3, which is consistent with the high simulated DMS emission flux there. In winter, the concentration of DMS in seawater is low, and so is the emission flux, and thus, the average contribution of DMS to the regional atmospheric SO2 concentration is only 0.12 μg/m3.The SO3. DMS has the highest contribution to the regional atmospheric 3, respectively. Unlike SO2, the enhancements in 2 in the atmosphere, while nce time , so it c2 and Overall, the release of marine biogenic DMS from China’s offshore regions enhances SO3.3.2.2 produced by the combustion of fossil fuels is also oxidized to eventually generate nss-2 emitted by human activities. It is now generally accepted that the only source of MSA in the atmosphere is the oxidation of DMS [−3, respectively, showing significant seasonal differences with higher values in summer and spring and lower ones in autumn and winter. Zhang et al. [−3 with the highest in spring and the lowest in winter, which is slightly different from our results. The observation data of the summer cruise survey in 2018 in the three China Seas show that the concentration of MSA in the atmosphere is in the range of 0.016–0.106 μg m−3, with an average of 0.045 μg m−3, which is close to our simulation results for the summer of 2017. Perraud et al. [3, which is basically consistent with our simulation results. It should be noted that the current understanding of atmospheric DMS oxidation pathways is not complete. MSA can be taken up in aerosols and clouds. Karl et al. [DMS emitted from the ocean is oxidized into MSA and non-sea salt sulfate  contributed by marine biogenic DMS. The calculated ratios of nss-bio/MSA range between 12–17, which are lower than the values of 18–20 reported by Savoie et al. [bio/nss-It can be concluded from e et al.  for the g et al.  in the Na et al.  estimatervations  and modervations  in the E3.4.Due to the confluence of marine; air masses and polluted air from coastal cities, the atmospheric environment of coastal cities will also be affected by marine biogenic DMS emissions. Therefore, under the condition of reduced anthropogenic sulfur emissions, the contribution and role of DMS emissions from polluted sea areas to the atmospheric environment of coastal cities should be reassessed.3.4.1.2 and 2, higher values appear in the Yangtze River estuary with contribution of 0.14 to 0.16 μg/m3 (about 4 to 8%). The SO2 concentration is weakly affected by DMS in the Shanghai city area near the Yangtze River estuary. Except for Baoshan and some urban district areas, where the contribution is ~0.13 μg/m3 (about 4%), the contribution of DMS to the SO2 levels in Shanghai is mostly around 0.08 μg/m3 (about 2%). The higher impact on 3 (about 10%). Compared with SO2, the impact of DMS on the 3 (about 5%). It should be noted that NOx emissions and hence NO3 radical concentrations are relatively low in clean, remote areas of the ocean. Thus, DMS is primarily oxidized by the OH initiated pathway in such areas. In contrast, NOx emissions and hence NO3 radical concentrations are higher in coastal areas with anthropogenic pollution. Thus, the NO3 pathway plays an important role in DMS oxidation in such environments. Both the day- and night-time oxidations of DMS are important in coastal areas with anthropogenic pollution while the daytime oxidation is the most important pathway in clean remote areas.The absolute and relative contribution of DMS to the annual average concentration of SO3.4.2.3 in Shanghai is shown in 3 concentration. This effect is relatively higher in tire sea area with a reduction of about 0.65~0.90 ppbv (about 1.5–2.5%). The impact of DMS emissions on the urban land area of Shanghai is relatively small, where the O3 concentration is reduced by 0.5 ppbv (about 1.25%) at the coastal line and 0.25~0.40 ppbv (about 0.5 to 1%) in most urban areas. The reactions of DMS with iodine monoxide (IO) and bromine monoxide (BrO) release iodine (I) and bromine (Br) atoms which react with O3 to reduce its concentration. In addition to the contribution to aerosols, marine biogenic DMS emissions also influence O3 which can be an area of further research.The absolute and relative contribution of DMS to the annual average concentration of O3.4.3.3− in fine-mode aerosol is quite different in the two airsheds. In the urban atmosphere of Shanghai, 16% NO3− aerosol is found in the fine-mode while only 5.2% of NO3− is present in the fine-mode in the marine atmosphere. This is likely due to the high removal rate of nitric acid in the marine air which contains relatively high concentrations of coarse alkaline sea salt particles. The fine-mode We calculate the relative amount of fine-mode aerosol in total aerosol (fine- and coarse-mode) and present the results in m et al. , our anas et al.  also sho4.−2 d−1, respectively, and the annual DMS releases can be estimated 0.008, 0.059, and 0.15 Tg S a−1, respectively. Although the continental shelf area accounts for a small proportion of the global ocean, the contribution to the global ocean DMS release cannot be ignored.A national scale database of DMS concentration in China seawater is constructed by combining the DMS measurements of historical cruise surveys from 2009 to 2017 in China’s continental shelf waters with DMS concentrations in seawater from the global database. The sea-to-air emission flux of DMS is calculated based on the database and the LM86 parameterization, which varies greatly in different seasons with the highest fluxes in summer and the lowest in winter. The DMS emissions in the entire simulated sea area for spring, summer, autumn, and winter are 0.13, 0.27,0.16, and 0.08 Tg S, respectively. The annual mean fluxes of DMS in the Bohai Sea, Yellow Sea, and East China Sea are 5.1, 6.9, and 8.8 μmol m2 in the atmosphere of the eastern coastal region of China, with the highest contribution in summer (0.63 μg/m3) and lowest in winter (0.12 μg/m3). The addition of DMS emissions also increases 3 in spring, 0.68 μg/m3 in summer, 0.32 μg/m3 in autumn and 0.20 μg/m3 in winter, respectively. Higher enhancements are predicted not only over seawater but also over coastal areas. The ratio of nss-bio/nss-At the regional scale, the addition of DMS emissions increases the concentration of SO2 levels in Shanghai is mostly around 0.08 μg/m3 (about 2%). In contrast with SO2, the impact of DMS on the 3 (about 5%). The model with DMS reduces the concentration of O3 in the atmosphere. The reduction of O3 is relatively larger in the open sea than in the urban area of Shanghai. The addition of DMS also increases fine-mode At the urban scale, the contribution of DMS to the SOSupplement1