The creation of pseudo-magnetic fields in strained graphene has emerged as a promising route to investigate intriguing physical phenomena that would be unattainable with laboratory superconducting magnets. The giant pseudo-magnetic fields observed in highly deformed graphene can substantially alter the optical properties of graphene beyond a level that can be feasible with an external magnetic field, but the experimental signatures of the influence of such pseudo-magnetic fields have yet to be unveiled. Here, using time-resolved infrared pump-probe spectroscopy, we provide unambiguous evidence for slow carrier dynamics enabled by the pseudo-magnetic fields in periodically strained graphene. Strong pseudo-magnetic fields of ~100 T created by non-uniform strain in  graphene on nanopillars are found to significantly decelerate the relaxation processes of hot carriers by more than an order of magnitude. Our findings offer alternative opportunities to harness the properties of graphene enabled by pseudo-magnetic fields for optoelectronics and condensed matter physics. The effect of strain-induced pseudo-magnetic fields on the optical properties of graphene has not been experimentally explored yet. Here, pseudo-magnetic fields reaching values of 100 T are shown to increase by more than an order of magnitude the relaxation lifetime of hot carriers in periodically strained graphene. Among the surprising properties is its exceptional mechanical strength4, which has spurred intense research activity on strain engineering of graphene5. Approximately a decade ago, the creation of gauge fields in graphene by harnessing non-uniform strain began attracting considerable attention as a potential route towards realizing previously unattainable physical properties in graphene6. Particularly, a theoretical study predicted that a uniquely designed strain in graphene could induce pseudo-magnetic fields that would allow electrons to behave as if they were subjected to a strong real magnetic field7. The strength of pseudo-magnetic fields in strained graphene can be orders of magnitude higher than the strength of external magnetic fields generated by superconducting magnets10, thus prompting researchers to experimentally verify the existence of such pseudo-magnetic fields. Since then, scanning tunneling spectroscopy (STS) measurements have repeatedly confirmed that pseudo-magnetic fields in mechanically deformed graphene can reach up to a few hundred T16. These giant pseudo-magnetic fields can form significant energy gaps7 and substantially modify optical transitions in the same manner as an external magnetic field20, but to a previously unattainable extent due to the high strength of pseudo-magnetic fields. However, the influence of pseudo-magnetic fields on the optical properties of graphene has not yet been experimentally verified.Since its discovery in 2004In this article, we present an experimental observation of the effect of pseudo-magnetic fields on hot carrier relaxation processes. The strain engineering platform employed in this study allows creating a non-uniform strain distribution with a maximum strain field of ~3.5% that is higher than other reported values for sustainable strain in graphene. The magnitude of the induced pseudo-magnetic fields is confirmed to be ~100 T via rigorous tight-binding simulations combined with the elasticity theory. Using time-resolved infrared pump–probe spectroscopy combined with theoretical modeling based on many-body interactions, we experimentally confirm that the induced pseudo-magnetic fields in our strained graphene system can decelerate the hot carrier relaxation processes by more than an order of magnitude.25. Graphene’s excellent mechanical property4 allows the accumulation of a large tensile strain at the edges of nanopillars10. The resultant non-uniform strain distribution near the edges of nanopillars can generate strong pseudo-magnetic fields, which force electrons to move in a circular motion as if they are under a strong external magnetic field8. Due to the preserved global time-reversal symmetry under the influence of strain-induced pseudo-magnetic fields, electrons in the K and K′ valleys experience pseudo-magnetic fields of opposite signs, thus circulating in opposite directions12. This cyclotron motion of the charge carriers corresponds to the creation of pseudo-Landau levels . Figure x and y directions as shown in the middle (26 (see Methods). This discrepancy between the simulated and measured maximum strain values is attributable to the inherent resolution limit of the Raman measurement with the diffraction-limited laser spot size21. By performing convolution on the simulated atomic-scale strain distribution by using a two-dimensional Gaussian corresponding to the spot size of the laser beam21, a realistic strain distribution that could be optically measured on the nanopillar was deduced, yielding a maximum strain value of 1.32%  at the atomic scale , a0 is the nearest carbon–carbon bond length (~0.14 nm), and 16, thus ensuring the reliability of our simulation (see Supplementary Note 4 for more details on the pseudo-magnetic field simulation). As shown in Fig. 10.Figure ift Fig.  by using32% Fig. . A compaale Fig.  was obtaR/R), which is directly proportional to the absorption in graphene for monolayer devices30. The measurement was performed at 4 K, unless stated otherwise, and low pump fluence (<1 mJ cm−2) was used to avoid any heating effect (see Methods for details). The probe pulse spot size was approximately 10 × 10 μm2, thus allowing us to probe a large number (>16) of highly identical nanopillars simultaneously for a large effective area possessing sizable pseudo-magnetic fields. The strength of pseudo-magnetic fields is negligible in graphene placed on flat surfaces . Figure ces Fig.  where thces Fig. , which ines Fig. , left exnes Fig. , right, λpump ~1030 nm) relax to the lower energy states rapidly within a few tens of femtoseconds through electron–electron scattering, thus inhibiting the absorption of probe pulses at the corresponding energy (λprobe ~1450 nm) due to Pauli blocking43. This decreased absorption in the control device was reflected in the rapid rise of the negative reflection change (−ΔR/R) . A subsequent slow relaxation process with a very weak intensity via the emission of acoustic phonons40 can also be observed in our sample, but only at higher pump fluences. In this study, we focused on the initial rapid carrier relaxation processes because of their importance in various crucial device applications49.To better understand the carrier dynamics of the device on nanopillars possessing pseudo-magnetic fields, we first performed control experiments involving the same monolayer graphene sheet on an entirely flat surface without nanopillars. In pristine graphene with massless Dirac cones Fig. , left, t2O3) to avoid any unexpected effects from substrate phonons51, which may influence the carrier dynamics. Immediately after pump excitation, −ΔR/R of the nanopillar device quickly rose and decayed on the same time scale as that of the control device. Surprisingly, −ΔR/R rose again very slowly until ~700 fs, followed by a slow decay with a time constant of ~1.66 ps. To illustrate the two distinct regimes, a detailed view over a shorter time range is shown in the inset of Fig. R/R in the rapid regime can be clearly attributed to pristine graphene with fast carrier relaxation processes . The carrier dynamics can be well captured by the Boltzmann-like scattering equation57, which is the effective theoretical tool to study the thermalization of hot carriers after pump excitations (see Supplementary Note 7 for more details).Optical Bloch equations based on many-body interactions were used to quantitatively understand the relaxation dynamics of charge carriers under the influence of pseudo-magnetic fields. The main many-body interaction process considered in the modeling was the electron–electron scattering that is the dominant relaxation mechanism in Landau-quantized grapheneR/R)  Fig.  because /R) Fig. , thus pr44 and highly efficient hot electron harvesting devices35. The light emission58 and population inversion properties46 in graphene can be improved drastically by slowing down the hot carrier relaxation processes through pseudo-magnetic fields.In summary, we have presented an experimental observation of the effect of pseudo-magnetic fields on the carrier relaxation processes in highly strained graphene. Our periodic nanopillar structure array achieves strong pseudo-magnetic fields of up to 100 T, which play a major role in enabling the observation of an extended hot carrier relaxation lifetime by more than an order of magnitude. The pseudo-magnetic field-induced slow carrier dynamics in highly strained graphene poses crucial implications towards the realization of a new class of graphene-based optoelectronic devices, including pseudo-Landau level lasers8. This design with uniform pseudo-magnetic fields may allow addressing individual Landau level transitions under a specific pseudo-magnetic field strength. Another disadvantage of graphene under pseudo-magnetic fields is that energetically degenerate transitions cannot be optically selected via circularly polarized radiation, while, for pristine graphene under real magnetic fields, circularly polarized radiation can selectively excite only one of two degenerate transitions33. Instead, we propose a possibility to harness a valley degree of freedom in strained graphene. As shown in Supplementary Fig. 49.One constraint of our nanopillar structure is that the obtained pseudo-magnetic field is spatially varying, thus inhibiting us to study the isolated effect of specific pseudo-magnetic field strength on the carrier dynamics. In Supplementary Fig. 59. In contrast, our nanopillar devices with highly strained graphene under pseudo-magnetic fields may possess disorder-assisted relaxation channels , which may dominate the carrier cooling process at a longer time scale59. A further study on the effect of symmetry-breaking supercollisions on the carrier dynamics at a longer timescale may provide further insights towards building pseudo-Landau-quantized graphene devices. By presenting experimental evidence of the effect of pseudo-magnetic fields, our finding offers a new landscape of opportunities towards creating pseudo-magnetic field-based graphene optoelectronic devices.It is also worth noting that for the cooling process at a longer timescale, optical phonons hardly fulfill the energy conservation and the momentum conservation in Landau-quantized graphene systems in external magnetic fields2/Si substrate using Raith e-line e-beam lithography system built in field-emission SEM (JEOL JSM-7600F). The substrate was then dipped in BOE  for 3 min 30 s at room temperature, followed by atomic layer deposition (ALD) for depositing a 20-nm Al2O3 layer on the entire substrate. The fabricated nanopillars have the lateral size of 300 nm -based wet-etching process. For an etching mask , we patterned polymethyl methacrylate resist  on SiO2, 512 × 512 pixel2 and 0.5 Hz, respectively. For Raman spectroscopy characterization, a 532-nm excitation laser was used along with a 100× objective lens. During the measurement, additional care was taken to keep the laser power low enough to avoid any heating effect. The strain-shift coefficient of 65.4 cm–1/%26 was used to estimate the maximum strain of 1.3% in our nanopillar device. The theoretical limit of spatial resolution  of our Raman system can be calculated using Abbe’s diffraction limit:λ is the wavelength of the excitation laser, and NA is the numerical aperture of the microscope objective. In our experiment, we used a 532-nm laser with a 0.90/100x objective lens, resulting in a spatial resolution limit of 361 nm.To analyze the structural characteristics and strain distribution of our nanopillar devices, we used a field-emission SEM , AFM , and Raman spectroscopy . The electron acceleration voltage in SEM was set to 10 kV. AFM measurement was performed on nanopillar sample in tapping mode. The scan size, resolution, and speed were set to 10 × 10 μmλprobe = 1450 nm) centered at the same spatial position. The spot size of pump and probe pulses were approximately 100 × 100 μm2 and 10 × 10 μm2, respectively. A pump fluence was approximately 0.4–1 mJ cm–2, which was adjusted by a continuously variable neutral density filter.Femtosecond pump–probe measurement was performed in reflection geometry. The sample was held in a closed-cycle helium cryostat . The pump pulses were generated from a femtosecond laser with a 230-fs pulse duration . The differential reflectance change was measured with a probe pulse  and final states . For the carrier–optical phonon scattering part, the scattering rate can be written as32:p, which is determined by Bose–Einstein distribution, and The main carrier dynamics mechanism we present in this study can be described by the Boltzmann-like scattering equationSupplementary Information


Physiotherapists play a key role in today’s healthcare and are recognised as the professionals in charge of rehabilitation, prevention and risk reduction . ProfessThe translation/back-translation was made by the Delphi Method with three rounds which were performed until de adaptation of the instrument to the Portuguese culture was achieved. A group of five experts, all with master and PhD academic degree, all with more than 25 years as Physiotherapist and Portuguese as their first language were selected.In order to reach consensus on the translation of the instrument, 3 rounds were carried out using the Delphi method, thus allowing linguistic equivalence to be obtained. In the 1st round of the process regarding the physical therapist's part, a 92 questions questionnaire was sent to the experts. In the 2nd round 42 questions were held and in the 3rd and final round, 5 questions were translated. Regarding the patient's part of the questionnaire, in the 1st round 18 questions were sent and in the 2nd round the number decreased to 9 questions. Consensus was achieved at 2nd round. The level of minimum agreement in each item was set to 80%, ensuring good translation and adaptation for Portuguese culture.The aim of the study was achieved, and the linguistic translation was completed. As next step, it is needed to conduct validation of the instrument for Portuguese culture by performing a pre-test. The results of this content validation by experts will be useful to improve the standard of care, teaching and research in physiotherapy, based on a standardised instrument which allow to measure Portuguese Physiotherapists professionalism, and perform international benchmark as well.


A high temperature of RTA (300–700 °C) was applied to graphene under an argon atmosphere to form defects on sp2 carbon lattices. The density of defects proportionally increased with increasing the RTA temperature. Raman scattering results confirmed significant changes in sp2 bonding. After 700 °C RTA, ID/IG, I2D/IG, and FWHM (G) values, which are used to indirectly investigate carbon-carbon bonds’ chemical and physical properties, were markedly changed compared to the pristine graphene. Further evidence of the thermally-induced defects on graphene was found via electrical resistance measurements. The electrical resistance of the RTA-treated graphene linearly increased with increasing RTA temperature. Meanwhile, the NO2 response of graphene sensors increased from 0 to 500 °C and reached maximum (R = ~24%) at 500 °C. Then, the response rather decreased at 700 °C (R = ~14%). The results imply that rich defects formed at above a critical temperature (~500 °C) may damage electrical paths of sp2 chains and thus deteriorate NO2 response. Compared to the existing functionalization process, the RTA treatment is very facile and allows precise control of the NO2 sensing characteristics, contributing to manufacturing commercial low-cost, high-performance, integrated sensors.This paper demonstrates the enhanced NO Furtholecules , and ult [−1 K1)  can guar2 [2 [3 [2S [Based on the material properties as mentioned above, various graphene sensors for the detection of O2 , CO2 [122 [2 [3 ,14, H2S 2 [3 [2S , et cete2 [3 [2S  have bee2 [3 [2S , electri2 [3 [2S ,13, and 2 [3 [2S ,15. Howe2 and NH3 detection. Furthermore, they demonstrated that the defect sites could be energetically more favorable for functionalization or decoration with nanomaterials. Although the RIE technique is very facile and appropriate for mass production, the accumulated damage to carbon-carbon bonds and increased oxidation sites after ion bombardment process severely affected charge transport property, and as such, the responsivity was decreased.Recently, facile methods based on the formation of lattice defects (mostly vacancies) on graphene sensing channels were studied to improve the sensing performance ,16. Lee 2 gas sensors. The generated graphene defects were confirmed by Raman spectra before and after RTA treatment. The RTA-treated graphene showed a remarkable increase in electrical resistance at metal-graphene-metal (MGM) contacts. Meanwhile, the NO2 response of graphene sensors exhibited the maximum responsivity of 24% and the response time of 111 s after the RTA treatment at 500 °C, which is about a two-fold enhancement compared with pristine (not RTA treated) graphene sensor (14%/304 s). Our results suggest that the RTA treatment can be a breakthrough approach to improving the NO2 sensing characteristics at low cost, thus contributing to manufacturing commercial low-cost, high-performance, integrated sensors.This report successfully demonstrates a facile method of creating graphene defects via rapid thermal annealing (RTA) to improve the performance of NO2/Si substrate  was used without further treatment, and the customized RTA system  and Nd:YAG laser (λ = 532 nm) at room temperature. The laser power was kept below 1 mW and the grating was 2400 L/mm. Wire program (version 3.4) was utilized to precisely designate peak position and intensity.DC was applied under an argon atmosphere (Pressure: ~7.0 Pa). The sputtering continued for 7 min with a deposition rate of ~0.5 nm/s. The spacing and the thickness of the electrodes were 100 μm and 200 nm, respectively.A shadow mask was used in DC magnetron sputtering process  to construct interdigitated gold (Au) electrodes. During the sputtering, ~315 V2 responsivity of the graphene sensor was analyzed in the custom-built measurement system (the temperature of the sample stage was maintained at 150 °C to improve the sensor’s recovery performance). At first, dry air as a balance gas was injected at 1 VDC and maintained for 20 min to eliminate unwanted gases and water molecules in the chamber. Then, the NO2 valve was opened, and the total flow, including the balance and target gases, was 500 sccm. The change in electrical resistance in response to the NO2 adsorption was recorded through electrical feed-throughs connecting to a SourceMeter  and sent to Lab-view software via a GPIB-to-USB converter for data collection and analysis.The NO2/Si substrate was used without further treatment (a), and the rapid thermal annealing (RTA) process was utilized to generate defects in graphene lattices (b). Previously, the RTA process was reported as a tool for generating defects on single-walled carbon nanotube (SWCNT) walls [A schematic fabrication process of the defected graphene-based gas sensor is shown in T) walls ,18,19. T2 sensing performance of the fabricated device was measured in a custom-built measurement system (e). The used measurement system is further discussed in Subsequently, Au-electrodes were sputtered through a shadow mask to fabricate the metal-graphene-metal (MGM) structured device (d). Au is generally used as electrode material in graphene devices because of its low contact resistance with graphene . The ins−1 and 2700 cm−1, respectively). Particularly in the case of pristine graphene (upper), D peak (at 1350 cm−1) is very weak and the I2D/IG value is relatively high as ~4, demonstrating a defect-free graphene monolayer [2D and IG refer to the intensities of 2D peaks and G peaks, respectively). On the other hand, the RTA-treated graphene shows an increased D peak intensity with a decreased I2D/IG value as ~1 in its Raman spectrum (lower), demonstrating the RTA-generated defects. Furthermore, three typical parameters extracted from each Raman spectrum are compared regarding the graphene qualities in D/IG value increased from 0.024 to 0.065, meaning increased defect density after RTA treatment. Furthermore, the I2D/IG value decreased from 4.1 to 1.0, and the FWHM(G) value increased from 14.5 to 18.6 . These parameters are generally utilized for evaluating the graphene quality, and all the parameter value changes demonstrated the degradation of graphene quality, implying the increased defect density of graphene [onolayer   [attices) ,18,19, sattices) .2 gas sensing performance of the fabricated device was studied. The expected NO2 sensing mechanism of the defected graphene device is described in 2 molecules adsorb onto the graphene surface, the concentration of major carriers  increases by the following reaction [Additionally, NOreaction .NO2→NO22 molecules is promoted, which enhances the NO2 response. The resistance change can be explained by the Fermi level shift  are locally electron-abundant due to the presence of oxygen-containing functional groups  . Thus, a2 sensors . The gray areas indicate where the target gas is injected. Here, the target- and base gases are 5 ppm NO2  and dry air, respectively, and 1 VDC was applied for each measurement. Additionally, the temperature of the sample stage was maintained at 150 °C during the measurement to improve the recovery performance. As the RTA temperature increased, the resistance of the corresponding device also increased. This is because the defect density increases as the temperature increases, as discussed above. However, in all the cases, the resistance decreased when the device was exposed to NO2 gas, meaning that all the device channels are p-type without polarity change.The time-dependent response curves are compared in gR and R0 are the minima- and maxima resistance values, respectively, in the area where target gas is injected. As the RTA temperature increases from 0 to 500 °C, the response of the corresponding device increases. However, the response somewhat decreases in the case of the RTA-treated sample at 700 °C. This phenomenon can be understood as the defect density increased as the RTA temperature increased, and the lattice structures were significantly damaged by high thermal energy at above a critical RTA temperature, resulting in deterioration of NO2 response.Here, off) can be reduced, and the response can be enhanced as well.In 2 gas molecules is promoted by the electron-abundant defected area as discussed above. However, the recovery times are almost the same for all the samples (~430 s), meaning that the RTA-generated defects do not affect the desorption rate of NO2 molecules.Additionally, each reaction curve’s response- and recovery times are compared b. The re2 sensors. As the RTA temperature increased from 300 to 700 °C, the corresponding device’s resistance gradually increased, whereas the NO2 response increased to 500 °C and decreased at 700 °C. This is because the defect density increased as the RTA temperature increased, and the graphene lattice is highly damaged above a critical RTA temperature, resulting in the deterioration of NO2 response. Interestingly, as the RTA temperature increased, the corresponding sensor’s response time decreased. The result implies that adsorption of NO2 molecules is promoted by the electron-abundant graphene defect areas. Our results suggest that the RTA process can be utilized to generate tunable graphene defects, and the defected graphene can be applied to high-performance gas sensor studies.In this paper, we demonstrated that graphene defects could be generated by RTA processes, and they could be utilized in high-performance NO


After 40 years of reform and opening-up policies, urbanization in China has significantly improved residents’ living standards; however, simultaneously, it has caused a series of health problems among Chinese citizens. Communities’ built environment is closely related to their residents’ health. However, few studies have examined the spatial differences in the health effects of community-built environments. Based on a 2013 health survey of residents in 20 communities in Wuhan, this study uses multilevel linear models to explore the effects of the built environment on residents’ health, analyzing the differences in its health-effect within different types of communities. The results showed that there were significant differences in the self-rated health status of residents in different communities, with those in high-end communities reporting a higher self-rated health status. The effect of the built environment on the health of residents in different communities was found to be inconsistent. For instance, the effect of the built environment on low-end community residents was very significant, but it was not obvious for residents in high-end communities. There are significant community-specific differences in the health- effect of the built environment: in high-end communities, residents’ health status was mainly restricted by travel accessibility, while in low-end communities, residents’ health status was mainly restricted by the accessibility of health facilities. Therefore, this paper proposes a built-environment optimization strategy for different types of communities to provide valuable insights for healthy community planning from a policy perspective. The rapid progress of urbanization and industrialization have significantly improved residents’ living standards; however, deteriorating urban environments threaten residents’ health ,2. AlthoAfter the housing reform, the urban housing paradigm changed from unit distribution to market circulation. The original multi-class dormitories and government offices began to collapse, while the commercialization of housing led residents of similar socioeconomic status to gather in similar communities; subsequently, the environmental differences between communities became increasingly obvious, and the residential space gradually showed a trend of stratification ,5.Unlike European and American countries, communities are subdivisions of urban streets and administratively formed towns in mainland China, and local governments have drawn geographical boundaries for communities. Residents’ committees are set up in communities as the grassroots management organizations in China. In Wuhan, for example, there are 13 municipal districts, 156 street offices, and 1431 community committees. Community is a spatial unit of residents’ daily lives, and the differences between its built environment and social environment may affect residents’ health status. However, few studies have explored the issue of community differences in the health-effect of the built environment, and it is difficult to provide adequate directives for the planning and construction of healthy communities.Therefore, based on the health survey data of community residents in Wuhan, this study uses multilevel linear models to discuss the following. (1) Are there any differences in the health status of residents in different types of communities? (2) How do the built environment’s elements affect residents’ health status? (3) Are there differences in the way the built environment affects health in different types of communities?Scholars from various countries have conducted a series of studies on the correlation betweem the built environment and health ,7,8. ForIn terms of community density, studies conducted in developed Western countries posit that a higher living density may promote residents’ physical activity, thus improving their health status . MedicalThe commercialization of housing has contributed to the stratification of living spaces, resulting in significant environmental differences in communities’ demographic structure, economic level, and health facilities . For exaWestern scholars have studied different types of communities and found that there are community differences in the effects of the economic level, demographic structure, and community environment on residents’ health . Fewer sAs an important city in central China, Wuhan has experienced rapid economic and social development; its urban space has been expanding, and its residential space has shown a distinctly heterogeneous pattern . The FifThe European five-dimension quality of life scale (EQ-5D) was used to measure health-related quality of life, including health-related behaviors, such as smoking, alcohol consumption, and physical activity. The Visual Analogue Scale (VAS) is a subscale of the EQ-5D used to measure the self-rated health status of the general population. The VAS shows respondents’ comprehensive evaluation of their self-rated health. A score of 100 represents the best health condition, and 0 represents the worst health condition.In this study, we used secondary data from the Fifth National Health Survey in Wuhan, conducted in September 2013, on 1922 residents in 20 communities  that werThe dependent variable in this study’s multilevel linear model is the residents’ self-rated health status level (continuous variable). The VAS score and utility value measure are important tools for describing residents’ quality of life, and their reliability and validity have been confirmed in prior studies . AlthougPersonal attributes were obtained from household survey data and community environment data from 2013, matching the time of the survey. The community environment was measured by taking the center of the community as a round point, and the appropriate distance of 800 m for residents’ daily activities as a radius , and theThis study uses residential characteristics as the basis for community evaluation and type classification to facilitate the exploration of community differentiation in the built environment, which affects residents’ health status. There are three main characteristics of residential types: architectural, neighborhood, and locational characteristics ,50,51. BSubsequently, the 20 analyzed communities were divided into two types: high-end and low-end. Among them, the 10 high-end communities included commercial houses with good location conditions and unit communities with good supporting facilities, whereas the 10 low-end communities included commercial houses, old unit communities, and old traditional neighborhood communities.The health status of residents is often influenced by both individual attributes and the community environment, thus forming a two-level nested structure of resident-community in the study data. However, existing empirical studies often use single-level regression models, such as multiple linear regression and structural equation models, which violate the assumption of mutual independence of variables in regression , ignore Therefore, this study uses a multilevel linear model to explore the spatial differences on the effects of the built environment on residents’ health using HLM 6.08 software. We first constructed three types of sample data: full sample, high-end community sample, and low-end community sample, and performed the following operations on each of the three types of samples. First, dummy variables were set for the categorical variables using SPSS26 software. Second, covariance detection was performed on the independent variables to exclude those that could not enter the model due to the presence of covariance. Third, the data were imported into HLM for Windows, version 6.08. Manufacturer: Scientific Software International, Inc. , and the null model analysis was conducted to determine the extent of between-group (community) differences and to assess the applicability of the multilevel linear model. Finally, the full model was constructed to explore the effects of each variable on residents’ health status at the individual attribute level and the community environment level.The full multilevel linear model equation is as follows:Resident-level regression equation:Community-level regression equation:i and j represent the resident and community levels, respectively; n indicates the number of resident-level variables; In the formula, p-value of 0.000, while the significance level was set at 0.05. This indicates that there are significant differences in the health status of residents in different types of communities.Regarding residents’ self-rated health status , the ave2. Additionally, 36% of respondents in the overall sample and 39.8% in high-end communities reported a housing area per capita of 30–60 m2. Lastly, 38.7% of respondents in low-end communities reported a housing area per capita below 30 m2.In terms of individual attributes, the percentage of women in the total sample was 54.2%. The average age of the residents surveyed was 47.7 years old, with most respondents (47.8%) being 40–60 years old. Compared with high-end communities, the proportion of elderly people (compared with that of young and middle-aged people) was significantly higher among residents of low-end communities. In the overall sample, 75% of respondents had a high school education or higher, while this value was 86% for high-end communities and 69.3% for low-end communities. Approximately 80% of respondents had medical insurance, but only 47.8% had undergone a medical checkup in the past year. The proportion of medical checkups was significantly lower in the low-end communities than in the high-end communities, which were 38% and 56.8%, respectively. Respondents’ average annual per capita household income was 39,900 CNY, with the highest percentage of respondents (39.3%) reporting an income between 10,000 and 30,000 CNY. The economic situation of residents in high-end communities was better, with 62% of them reporting an annual per capita household income above 30,000 CNY, while only 45.2% of respondents in the low-end communities reported such income. In terms of housing area per capita, respondents’ mean housing area per capita was 46.78 m2, while the density of medical facilities in high-end communities was significantly higher than that in low-end communities. The mean value of park square area was 8.3 ha, while that in high-end communities was 9.33 ha, and that in low-end communities was 7.28 ha. In terms of travel accessibility, the mean value of traffic station density in the sample communities was 6.01/km2, and the mean value of intersection density was 11.77/km2. Low-end communities have higher traffic station density and intersection density than high-end communities, which may be due to the fact that most of the low-end communities are historical communities that occupy a better location in the city due to their earlier construction [With regard to community attributes, all the indicators were continuous variables. In terms of the medical environment, the mean value of medical facility density in the buffer zone of the sample communities was 12.8 units/kmtruction . In termp-value of 0.000, indicating that the models passed the test and that the between-group variance (community) of each model was greater than its standard error, which indicates that the differences in the health status of the population originated largely from community differences [This study first constructed null models of the community-built environment with residents’ health status for three types of samples. Only the dependent variables were substituted, and no independent variables were substituted to determine whether the samples were suitable for multilevel linear models and to analyze the extent to which differences in residents’ health status originated from community differences. All three models were tested using the chi-square test with a ferences ; howeverferences . That isferences . The samThe analysis in Analysis of the full-sample regression results in For high-end communities, only three built-environment variables  were significantly associated with self-rated health status. Combining this finding with the ICC and between-group variance reduction ratios described above, it is clear that the self-rated health status of residents in high-end communities is less affected by the community’s built environment. This is because the residents of the high-end communities analyzed in this paper were mainly young and middle-aged people, who generally have higher income and education, as well as stable jobs, enjoy a wider social circle, have better travel ability, and more areas for activities, while the small-scale community built environment does not have a significant effect on this group ,64.Furthermore, in high-end communities, the density of traffic stops and intersections both had a significant positive effect on health status, suggesting that the self-rated health status of residents in high-end communities is mainly governed by accessibility . On the For low-end communities, all built environment variables, except for population density, had a significant effect on residents’ health status, and the regression coefficients were higher than those of high-end communities. Combining the ICC with the between-group variance reduction ratio, it is clear that the self-rated health status of residents in low-end communities is more influenced by the built environment around the community. Because of the limited radius of their daily activities, the most significant association with health status is the built environment around the community in a small area .All health facility variables had a significant positive effect on residents of low-end communities. The health status of residents of low-end communities was mainly governed by the accessibility of health facilities . Unlike Building density has a significant negative effect on the residents of low-end communities, while the floor area ratio had no significant effect.Among the health effects of the built environment, most of our findings are consistent with those of Western countries. However, some findings are of interest with regard to intersection density, building density, and floor area ratio. In contrast to prior Western studies , in this2, the residential land density is 70.5%, and the building density is 67.5%. With a floor area ratio of 2.63, the building density is extremely high and there is a noticeable lack of roads and public space, which produces a series of problems, such as overcrowding, air pollution, and noise pollution.Empirical studies in developed countries reveal that a high-density residential environment helps promote physical activity and reduces health risks among residents ,45. HoweOver the 40 years of rapid urbanization in China, the pattern of spatial differentiation of living space has been clearly formed. New urban areas have a good built-up environment and bring together a number of high-end communities. According to the descriptive statistics of the sample, most of these communities are high-volume/low-density commercial housing, and the building density is much smaller than that of the low-end communities, so there is no disadvantage of high building density . HoweverThe old city is also dotted with a lot of low-end communities. Based on the statistical description of the sample, most of these communities are low-volume/high-density and have a complex type of residence, a single type of land use, and a lack of activity space. High residential density not only affects the residents’ leisure-oriented physical activities and reduces their physical activity level but also hinders airflow and increases their exposure to air pollution .By comparing the residents of the two communities, we found that most of the residents of high-end communities are young and middle-aged, with good travel ability, less influenced by the surrounding built environment, and can travel to other areas of the city to obtain health resources. Their health status is also mainly governed by “travel accessibility.” In contrast, most of the residents of low-end communities are middle-aged and old, with limited travel ability, and are greatly influenced by the surrounding built environment. Their health status is mainly governed by “health facilities’ accessibility.” However, there are often fewer public service facilities, such as medical facilities, green areas, and squares, in the old city, resulting in health inequity.Through the above findings, we observe that: the ultra-high density of China’s big cities, the incomplete facilities, inadequate functions, and insufficient public and social services in old neighborhoods are urgent problems to be solved. At present, China’s urbanization process has shifted from high-speed development to high-quality development and from incremental planning-oriented to stock planning-oriented. Based on this, the Chinese government has been carrying out large-scale urban renewal and has issued guidelines for the construction of 15-min living circles and complete residential communities . The govA limitation of this study is that it uses the place of residence as the geographic context of residents to study the built environment based on their self-rated health.However, since the residents’ activity locations also include their workplaces, shopping places, and others, there is a deviation between the static residential units and the geographic context of their real experiences, creating an uncertain geographic context problem . TherefoIn this study, we used multilevel linear models to explore the influence of the built environment on residents’ health status in 20 communities in Wuhan, and analyzed the differences in the effect in different types of communities. The main findings are as follows: (1) There are significant differences in the health status of residents in different types of communities, as residents in high-end communities have higher self-rated health levels. (2) The extent to which the differences in residents’ health status originate from the community varies; a large proportion of the differences in the health status of residents in low-end communities and a small proportion of those in the health status of residents in high-end communities originated from the community itself. (3) The degree of influence of the community-built environment on residents of different types of communities is inconsistent; specifically, residents of low-end communities belong to more disadvantaged groups and have a more limited travel radius, while their health behaviors and health status are more significantly influenced by the community-built environment. Further, residents of high-end communities have higher socioeconomic status and travel ability, and the effect of a small-scale community-built environment on them is not obvious. (4) There were differences in the action of the community-built environment on the residents’ self-rated health status. Residents of low-end communities are mainly constrained by the accessibility of health facilities and building density, while residents of high-end communities are mainly influenced by the accessibility of travel and floor area ratio.Based on these findings, the conclusions of this study are as follows. A spatial differentiation pattern of living in Wuhan has clearly developed , and theWithin the context of urban renewal and the “Three Old” reform, we should strictly control building density, build pocket parks, administer the street space correctly, set up more community centers, improve the accessibility of health facilities, and provide residents with a high-quality food environment. Most of the high-end communities in this study comprised high-volume/low-density commercial housing, where residents have a relatively high socioeconomic status and their health conditions depend on travel accessibility. Therefore, following the perspective of urban incremental construction, land should be utilized in an appropriate and intensive manner , and the


Sarcoidosis‐lymphoma syndrome describes a pathological state wherein both sarcoidosis and lymphoma are present. Sarcoidosis and lymphoma may occur concurrently, or sarcoidosis may precede lymphoma. There are few reports which have previously described the temporal progression from lymphoma to sarcoidosis. Here, we present a patient with stage II diffuse large B‐cell lymphoma in the right breast. The patient achieved complete remission after chemotherapy. Five years after remission, the patient visited our clinic with newly developed enlarged mediastinal lymph nodes; lymphoma recurrence was suspected. However, mediastinal lymph node biopsy showed numerous noncaseating granulomas with no evidence of malignancy in the mediastinal lymph nodes. Consequently, a diagnosis of sarcoidosis was made. This case report highlights the need for pathological confirmation following biopsy when recurrence of lymphoma is suspected. We present a rare case of extremely delayed‐onset sarcoidosis mimicking mediastinal lymphoma recurrence after complete remission of diffuse large B cell lymphoma (DLBCL). Because CT and PET scans are insufficient for definitive diagnosis, pathological confirmation through biopsy is warranted when recurrence of lymphoma is suspected. Sarcoidosis and lymphoma are generally considered mutually exclusive diseases. However, in 1986, Brincker coined the term “sarcoidosis‐lymphoma syndrome” (SLS) to describe their occasional association.Here, we present a case of delayed sarcoidosis onset five years after complete remission (CR) of lymphoma.In October 2013, a 52‐year woman visited our hospital with a palpable breast mass. A right breast biopsy revealed medium to large‐sized monomorphic malignant lymphoid cells with CD 20 positivity Figure . The patFive years after CR, the patient returned to the clinic when chest CT scan showed enlarged mediastinal lymph nodes Figure . Her bloNo ethical committee approval was required for this case study, which is in compliance with institutional and national policies. The patient consented to the publication of clinical details and images concerning the case.Several common features of SLS have been previously described in the literature. Overall, lymphoma is observed 5.5 times more frequently in patients with sarcoidosis than in the general population.Sarcoidosis is a systemic disease characterized by granulomatous inflammation in affected organs. The pathogenesis of pulmonary sarcoidosis involves antigen presentation followed by CD4+ activation in regional lymph nodes, and subsequent organization of macrophages into granulomas.The clinical presentation of sarcoidosis after lymphoma treatment involves incidental mediastinal or hilar lymphadenopathy with no constitutional symptoms.The prognosis of sarcoidosis after lymphoma is generally mild. In our case, the six‐month follow‐up CT scan showed a marked decrease in mediastinal lymph node size. This is in agreement with a previous report in which only 41% of patients required treatment, whereas 36% of patients required oral corticosteroids; 91% of those patients showed a complete clinical response.In conclusion, we present a rare case of delayed‐onset sarcoidosis mimicking mediastinal lymphoma recurrence after CR of DLBCL. Because CT and PET scans are insufficient for a definitive diagnosis, pathological confirmation through biopsy is warranted when recurrence of lymphoma is suspected. An observational treatment strategy is reasonable in asymptomatic patients with normal pulmonary function tests.The authors declare that there are no conflicts of interest.


The generation of defects is studied at first by considering the influence factors . Then uniaxial tensile test simulations are conducted to uncover the evolution of the mechanical performance of graphene/MoS2 heterostructure after being irradiated by ions. At last, the control rule of interlayer distance in graphene/MoS2 heterostructure by ion irradiation is illustrated for the actual applications. This study could provide important guidance for future application in tuning the performance of graphene/MoS2 heterostructure-based devices by ion beam irradiation.The interaction between ion irradiation and two-dimensional (2D) heterostructures is important for the performance modulation and application realization, while few studies have been reported. This paper investigates the influence of Ar ion irradiation on graphene/MoS Over the past two decades, more than ten thousand articles have been published every year around the topics of 2D materials. Graphene, as a single layer of graphite, is the most important 2D material. The special atomic and electronic structure has endowed graphene unparalleled properties3 and therefore, great application potentials are expected5. Besides graphene, there are also other types of 2D materials such as hexagonal boron nitride, black phosphorus, molybdenum disulphide (MoS2), and other transition metal dichalcogenides being discovered in the last a few years. On one hand, these 2D materials behave lots of outstanding properties similar to graphene. On the other hand, they also exhibit special performance to compensate the weakness of graphene6. Together with graphene, the big 2D material family opens up a new era of nanomaterials research.Two-dimensional (2D) materials have become the focus of nanomaterials research since the experimental discovery of graphene in the lab in 20045 cm2 V −1 s−1 of graphene has indicate its significant potential application in electronic devices7, while the graphene-based field effect transistors (FETs) generally behave low on/off switching ratios due to the zero bandgap. In contrast, 2D MoS2 has the direct bandgap of 1.8 eV8, which enables the MoS2-based device on/off switching ratios of > 108, but the relatively low mobility limits its further applications9. To overcome the shortages of each material, the idea of combining different components together, i.e., generating 2D heterostructures, has emerged in recent years. 2D van der Waals (vdWs) heterostructures are one type of heterostructures which stack one layer of 2D crystal on top of another, analogous to building Lego blocks10. This vertical stacking feature provides the in-plane strong covalent bonds, whereas relatively weak interlayer vdW forces to the structure, which is able to integrate the merits of each 2D crystal, as well as generate some new features due to the synergistic effect, largely expanding the applications of 2D materials11. For example, by combining the high conductive graphene with semiconducting MoS2, we could fabricate high performance transparent and flexible memory devices12. Besides, integrating the high optical absorption and 1.8 eV direct bandgap features of MoS2 with high carrier mobility of graphene enables the scalable fabrication of phototransistors13.During the research of 2D materials, it is found that lots of the individual 2D material has the intrinsic drawbacks which impede the full realization of the applications. For example, the high mobility of 2 × 1015. However, it should be aware that the as-synthesized vdW heterostructures generally exhibit weak interlayer coupling and uncontrolled properties, which means the postprocessing and performance modulation should be applied to the heterostructures to adjust the performance before being used. Therefore, the discovery of suitable performance modulation methods for vdW heterostructures is important. The current proposed techniques, such as mechanical-based transfer-and-stack method18, external pressure field19, external electric field20 and thermal annealing method21, have been demonstrated to be able to be successfully applied in tuning the interlayer coupling of vdW heterostructures. However, these methods are either too complex , or unable to be precisely controlled , or relying on large external field . It is therefore desirable to explore new techniques to modulate the interlayer coupling in 2D vdW heterostructures for their further application.The outstanding properties of 2D vdW heterostructures have promised them wide application potential similar to 2D materials. To realize the applications, a lot of efforts have been made to synthesize vdW heterostructures24. After ion irradiation, the mechanical, optical and electrical properties of 2D materials can be adjusted efficiently, and this process is highly dependent on the irradiation conditions 26. The usage of ion irradiation in tuning the performance of vdW heterostructures is less reported28, especially for graphene/MoS2 heterostructures, which is the most typical 2D vdW heterostructure. To uncover the performance modulating mechanism of graphene/MoS2 heterostructures by ion irradiation, the first thing is to make clear the ion irradiation induced phenomena in the heterostructure. In this paper, we systematically studies the influence of Ar ion irradiation on graphene/MoS2 heterostructure by using molecular dynamics (MD) simulations. The irradiation induced structure evolution, and the influence factors are discussed, focusing on the generated defects and the sputtered atoms. The influence of irradiation on the uniaxial tensile properties of graphene/MoS2 heterostructure are then investigated for the actual application under loading conditions. At last, the possibility of controlling the interlayer distance by ion irradiation are discussed. The results in this paper could provide important supports for choosing the ion irradiation method in performance modulation of 2D vdW heterostructures.The ion beam irradiation technique has already been demonstrated in the application of tuning the properties of 2D materials, through generating defects, or forming doping, or thinning the materials29 is adopted due to its strong capability in nanomaterials simulation. Ar ions are chosen as the representative irradiation ions, and vertically irradiated onto MoS2/graphene heterostructures with various energy and dose, as shown in Fig. 30 to eliminate the side effect of the pressure waves generated due to the ion irradiation. The suspended graphene/MoS2 heterostructure has an in-plane size of 115 × 130 Å with 11,124 atoms. The initial interlayer distance between MoS2 and graphene is set as 3.5 Å owing to the minimized potential energy at around this value31. For the supported cases, SiO2 is chosen as the substrate with a thickness of about 58 Å. This thickness, which results in a total number of atoms of 74,988, is enough to withstand the irradiation effect in the studied energy range. The Ar ions are randomly irradiated from a cubic box 40 Å on top of the heterostructure plane, and only the nuclei collision is considered due to much weaker energy transfer from the electron collision32.For all the simulations, the large scale atomic/molecular massively parallel simulator (LAMMPS) package2 is described by a second-generation reactive empirical bond-order (REBO) potential developed by Liang et al.33, which was well demonstrated by different groups35. The interactions between the carbon atoms (C–C) in graphene is captured by adaptive intermolecular reactive bond order (AIREBO) potential36, which could consider the formation and dissociation of covalent chemical bonds, enabling it to model the bond breaking and formation during the irradiation process. A Tersoff potential37 is applied to consider the interactions in SiO2, and the Ziegler–Biersack–Littmark (ZBL) universal repulsive potential38 is adopted to model the energetic collisions between Ar and the target atoms due to its strong capability in describing the interactions at small separation. The MoS2 and graphene layers are coupled by vdW interactions, which are considered by the Lennard–Jones (LJ) potential39. Besides, the interactions between graphene/MoS2 with the SiO2 substrate are also described by the LJ potential. For the parameters used in the LJ potentials , please refer to Ref.41.To describe the multiple interatomic interactions between different atoms in the system, a hybrid potential strategy is applied. The interaction of the atoms in MoS42. Besides the simulation of irradiation process, the mechanical properties of the irradiated structures are also revealed by uniaxial tensile simulations. The irradiated configurations are extracted from the aforementioned results and then relaxed at room temperature for enough time. Afterwards, uniaxial stretching process is applied on the structure at room temperature condition with a strain rate of 0.003 ps-1. It was demonstrated that the tensile strength of single-layer 2D materials would increase with strain rate43, while the effect maybe limited for bilayered 2D structure44. The value of strain rate used in this study is comparable to the previous study, and the influence of strain rate would be studied in the future research. Thereafter, the information of stress/strain is derived based on the method in Ref.45, then the stress–strain curve is plotted and the values of fracture stress/strain are extracted. The configurations of the stretched heterostructures are visualized by the Visual Molecular Dynamics (VMD) package46.The MD simulation process for the ion irradiation is constituted by four stages. At the first stage, the system is relaxed at 300 K by an NVT ensemble for 5 ps to achieve an equilibrium state. At the second stage, consecutive ions with different parameters (energy and dose) are irradiated onto the heterostructure, for which the ions are emitted every 1000 timesteps and the system is kept at 300 K during the irradiation process. At the third stage, a high temperature (2000 K) annealing process is applied on the system for 30 ps to simulate the actual annealing effect in real experiment. At the last stage, the system is rescaled to room temperature (300 K) after the annealing process, and stayed at 300 K eventually. This four-stage scheme is successfully demonstrated in simulating the irradiation phenomena by different studies13 /cm2, the top-layer MoS2 receives most of the impact momentum, which results in the sputtering of Mo and S atoms and generates lots of vacancy defects , while the bottom-layer graphene is less influenced. Actually, under this irradiation condition, the MoS2 acts as a protective layer to avoid the graphene layer being damaged. The generation of vacancies in the 2D materials and 2D heterostructures can be used to modulate their properties. For example, H. K. Neupane et al.47 demonstrated that the vacancy defects at Mo sites could be used to efficiently tune the electronic and magnetic properties of 2D graphene/MoS2 heterostructure. Vacancies also affects the mechanical, electrical and magnetic properties of MoS248. The existence of vacancies can be beneficial or detrimental to the performance of the heterostructure, depending on the location and density of the defects. Therefore, to achieve the desired properties of the heterostructure, the ability to control the defects generation is significant. The next section of this paper focuses on the dependence of the generation of vacancies on ion irradiation energy, irradiation dose, substrate, stacking order, to offer important guidance for actual applications.Under ion irradiation, the structure of heterostructure would vibrate and the system becomes unstable. Defects would be induced into the system if the irradiation energy is high enough. As shown in Fig. 2 is limited, and the bottom-layer graphene is fully protected. With the increase of irradiation energy (200 eV), the generation of vacancies in both MoS2 and graphene would be intensified. Under this situation, the defects in top-layer MoS2 would be more severe than in bottom-layer graphene. If the irradiation energy is further increased (1000 eV), the defects in MoS2 is slightly changed, while the defects in graphene increase a lot, generating a more severe defect formation in graphene. For the low energy irradiation case, very little energy traverse through the top-layer plane, and the bottom layer is well protected. While for the high energy irradiation case, some energetic ions pass through top-layer, and collide with the bottom-layer, inducing the direct vacancy formation in the graphene. Besides, the sputtered Mo and S atoms from the top-layer MoS2 are also energetic at this condition, and they would fly to the graphene and lead to the second collision and indirect vacancy formation in the graphene layer. The generation of indirect defects in graphene become dominate if the ion energy is high enough, which could explain the reversed phenomenon observed in the 1000 eV case.For 2D materials under ion irradiation, the influence of irradiation energy and dose on the defect formation is important, so do 2D heterostructures. As shown in Fig. 2 and graphene layers, to obtain a graphene/MoS2 heterostructure, so that top-layer graphene acts as a protective layer to MoS2. Figure 2 layer for MoS2/graphene and graphene/MoS2 heterostructures. The case study of monolayer MoS2 is also provided as a reference. It shows that under the low ion irradiation energy (40 eV), the defects of MoS2 in the two types of heterostructures are always fewer than the pure monolayer MoS2 case, indicating a protective effect of the graphene to MoS2 layer, regardless of the stacking order of heterostructures. In the graphene/MoS2 heterostructure, the shielding effect of top-layer graphene could mostly relieve the irradiation damage onto bottom-layer MoS2, while in MoS2/graphene heterostructure, it is the interaction between bottom-layer graphene and top-layer MoS2 weakening the irradiation damage onto MoS2. If the irradiation energy is increased to 400 eV, it is found that the bottom graphene can still reduce the irradiation effect of MoS2. While for the graphene on top (graphene/MoS2 case), the irradiation damage is more severe, which is attribute to the indirect collision from the sputtered carbon atoms in top graphene layer. For the top-layer 2D crystal, the switch from protective effect to destructive effect at different energy levels corresponds to the results in Fig. The influence of the stacking order is investigated by switching the MoS2 layer under different irradiation energies for the aforementioned three cases. It clearly shows that the number of sputtered atoms in MoS2 for MoS2/graphene is always lower than monolayer MoS2 case, demonstrating a perpetual beneficial effect of the bottom-layer graphene regarding the irradiation damage on MoS2. For graphene/MoS2, there is no damage on MoS2 if the irradiation energy is smaller than 100 eV, then the number of sputtered atoms quickly climbs up to surpass the results in MoS2/graphene case. It even becomes the most severely damaged when the irradiation energy is above 400 eV, indicating that the indirect collision dominates under this energy level.Figure 2 and MoS2/graphene heterostructure, the number of sputtered atoms in MoS2 increases almost linearly with the increase of ion dose within the studied range. Due to the protective effect of the bottom graphene, the increase rate of MoS2/graphene is smaller. It is expected that at a higher dose beyond the studied range, the number of sputtered atoms would gradually achieve a steady value. In addition, due to the shielding effect of the top-layer graphene, the number of sputtered atoms in graphene/MoS2 is always zero under this irradiation energy.For the influence of the irradiation dose, we choose the irradiation energy of 100 eV and compare the data of three cases in Fig. 49. To make clear the influence of substrate on the ion irradiation effects of the heterostructures, we plot the relationship between the number of sputtered atoms and irradiation energy for the supported and suspended cases in Fig. The actual application of 2D heterostructures normally cannot be separated from the substrate. The existence of substrate has demonstrated to greatly affect the growth and properties of 2D heterostructures2 is more severe damaged under substrate supported case, the bottom-layer graphene remains undamaged, which means that the substrate influences the interaction between graphene and MoS2. It was described previously that the graphene-MoS2 interaction can bring beneficial effect to the irradiation resistance of MoS2, therefore, the existence of substrate weakens this beneficial effect. For the high ion energy irradiation (400 eV), the top-layer MoS2 is more severe damaged under supported case, in addition, the bottom-layer graphene is also a little bit more damaged under supported case. Especially, there exists some defects in the un-irradiated sites for the supported case. Under high energy irradiation, the impact of ions not only induced the direct collision with the heterostructure layers, but also it resulted in the sputtered of substrate atoms, which could generate second collision (indirect collision) between the substrate atoms and heterostructure atoms. The indirect collision from the substrate can intensify the damage effect in MoS2, and due to the random sputtering of the substrate atoms, there would be some defects randomly generated in graphene. Besides, the existence of substrate can also lead to the rebound of the carbon atoms in graphene, which would generate the indirect collision with the atoms in MoS2 as well. Therefore, there exists two different mechanisms for the ion irradiation phenomena under the supported case, i.e., the weakened MoS2-graphene interaction, and the generation of indirect collision due to the existence of substrate. Under low irradiation energy, only the weakened MoS2-graphene interaction mechanism exists, with the increase of irradiation energy, the generation of indirect collision mechanism dominates eventually.To uncover the mechanism underlying the phenomenon in Fig. 50. The ion irradiation process could provide tailored mechanical behavior to heterostructures if the generation of defects could be controlled. To understand the influence of the ion irradiation on the mechanical properties of the MoS2/graphene heterostructure, we conduct uniaxial tensile test simulations for the ion irradiated heterostructures with different irradiation parameters.2D materials and the heterostructures exhibit special mechanical behaviors such as high in-plane strength and stiffness, banding flexibility, which are highly valuable for their applications2/graphene and ion irradiated MoS2/graphene exhibit a two-stage fracture process under tensile loading. The phenomenon of a two-stage process is attributed to the different tensile behaviors of MoS2 and graphene layers. However, a quite different tensile fracture behavior could be observed. Firstly, for the original MoS2/graphene heterostructure, the initiation of cracks for the first and second stages happens at a larger strain when compared to the ion irradiation case , indicating a reduced fracture strain due to the ion irradiation process. Secondly, the cracks of the original MoS2/graphene heterostructure initiate at the bottom-layer graphene (first stage), then the cracks start to initiate at the top-layer MoS2 at a larger strain (second stage). While for irradiated MoS2/graphene heterostructure, the fracture sequence is reversed, i.e., the initiation of crack for the first stage happens at top-layer MoS2, and the initiation of crack for the second stage happens at bottom-layer graphene. The reduced fracture strain in irradiated MoS2/graphene is owing to the generated defects, which is commonly observed in the irradiated 2D materials. For the reversed fracture sequence, it is also related to the induced defects. The pristine perfect MoS2 layer has a larger fracture stress/strain compared to the perfect graphene layer, suggesting a preferential fracture process in graphene, as observed in Fig. 2/graphene under 100 eV ion irradiation, the defects are mainly generated in top-layer MoS2, resulting an inferior mechanical tensile strength compared to graphene. Therefore, the tensile stretching process leads to the cracks starting from the damaged MoS2.The typical configurations of the heterostructure under different tensile strains are provided in Fig. 2/graphene heterostructure at different irradiation energies. It clearly shows that all the structures behave a two-stage fracture process, owing to the different tensile behaviors of MoS2 and graphene layers, and the ion irradiation induced defects. The second fracture stage represents the continuous stretching process of top-layer MoS2 or bottom-layer graphene, depending on the ion irradiation parameters. The original MoS2/graphene has longest second fracture stage due to the defect-free feature, while the irradiated heterostructures have different lengths of second stage due to the distinct defects induced under the different situations. Besides, it is seen that the fracture stress (maximum stress) decreases with the increase of irradiation energy, which corresponds to the increased sputtered atoms with the increase of ion energy. The Young’s modulus also decreases with the increase of ion energy.Figure The experimentally synthesized 2D heterostructures usually exhibit weak interlayer coupling due to the loose interaction induced by the large interlayer distance. Ion irradiation could induce impact force to the 2D layers, bringing defects into the 2D crystal and meanwhile, induce the modulation of the interlayer distance.14/cm2) could induce a slight of the distance due to the limited impact momentum, while at a large ion dose (7.91 × 1014/cm2), the interlayer distance achieves a much smaller value. Figure 27. The precise modulation of the interlayer distance is significant to other properties as well, which would be the focus of our future studies.Figure However, the impact force would also bring defects to the 2D crystals if the irradiation energy is high. As shown in Fig. 2/graphene heterostructure. The main conclusions are as follows.Under ion irradiation, there would be some vacancies generated in the 2D crystals, while the 2D layers response differently to ion irradiation. For the low energy ion irradiation, the top-layer 2D crystal could shield the bottom-layer, while for the high energy ion irradiation, the indirect collision induced by the top-layer would intensify the irradiation-induced damage into the bottom layer. The bottom-layer 2D crystal would always relieve the defect generation in top layer, regardless of the ion irradiation energy. The irradiation induced vacancies would increase linearly with the increase of ion dose for different study cases. And the substrate would reinforce the irradiation effect because of two mechanisms, i.e., the weakened interlayer coupling in heterostructure at low ion energy and the indirect collision at high ion energy.2/graphene heterostructure due to the generated defects. The tensile behavior is highly dependent on the irradiation parameters.Ion irradiation would result in the reduction of tensile fracture stress and strain, and the reversed tensile fracture sequence for MoS2/graphene heterostructure could be well controlled at a certain ion irradiation dose and energy. While relatively high ion irradiation energy would lead to the coexistence of the defects with reduced interlayer distance.The interlayer distance in 2D MoSBased on classical molecular dynamics simulations, this paper studied the ion irradiation induced phenomena in 2D MoSThis study is meaningful for the application of ion irradiation on nanomanufacturing. The future research would focus on the electronic performance modulation and the actual application of ion beam irradiation on tuning the performance of 2D heterostructure-based devices.Supplementary Video 1.Supplementary Video 2.