Titanium is a commonly used material in aviation, aerospace, and military applications, due to the outstanding mechanical properties of titanium and its alloys. However, its relatively low thermal conductivity restricts its extended usage. The use of graphene as a filler shows great potential for the enhancement of thermal conductivity in titanium-based metal-matrix composites (MMCs). We used classical molecular dynamics (MD) simulation methods to explore the thermal conductance at the titanium–graphene (Ti/Gr) interface for its thermal boundary conductance, which plays an important role in the thermal properties of Ti-based MMCs. The effects of system size, layer number, temperature, and strain were considered. The results show that the thermal boundary conductance (TBC) decreases with an increasing layer number and reaches a plateau at n = 5. TBC falls under tensile strain and, in turn, it grows with compressive strain. The variation of TBC is explained qualitatively by the interfacial atomic vibration coupling factor. Our findings also provide insights into ways to optimize future thermal management based on Ti-based MMCs materials. Compared with other metals, titanium and its alloy derivatives are known for their excellent physical properties, stable chemical properties, and great biocompatibilities and are widely applied in aerospace , the mil−1 K−1) [Due to outstanding properties, such as high thermal conductivity (~3000 Wm−1 K−1) ,11, mech−1 K−1) ,13, and −1 K−1) , graphen−1 K−1) ,18,19,20−1 K−1) ,22. Grap−1 K−1) ,23. Grap−1 K−1) ,24,25. T2 K. However, there is still a vacuum in the research on the physical mechanism behind this phenomenon.The thermal conductivity of Ti-based metal-matrix composites increases with amount of graphene, as confirmed through the experiments in the previous studies ,26,27,28In this work, we study the thermal boundary conductance at the Ti/Gr interface using both non-equilibrium molecular dynamics (NEMD) and thermal relaxation (TR) methods. The NEMD simulation is helpful in understanding the thermal conductivity of the composite and the TR method mimics the experimental laser-based pump-probe process. The relationship between the thermal boundary conductance and the phonon spectra at the interface is discussed in great detail. Our work suggests that the thermal properties of titanium can be greatly improved by affiliating an appropriate amount of graphene. In addition, compressive strain is an effective method to enhance the TBC of the Ti/Gr interface. Ti is a kind of metal with hexagonal closest packed (HCP) structure. We chose three of the most common crystal faces, Ti(10-10), Ti(11-20), and Ti(0001), as shown in Ti−Gr = 0.36 nm and εTi−Gr = 0.006535 eV [All molecular dynamics (MD) simulations were performed using the large-scale atomic/molecular massively parallel simulator (LAMMPS) package . The modTo calculate the TBC based on the NEMD, simulations were conducted using the nonperiodic boundary condition model b, in whi6 steps) to relax the structure of the system and to optimize the interlayer distance. Afterwards, the system was then switched to the microcanonical ensemble (NVE). The initial temperature gap could be generated by increasing the temperature of the graphene layers instantaneously to a specified value by rescaling the velocities of the carbon atoms [5 steps under five independent simulations. The slope of a linear fitting is the heat capacity at the interest temperature. In the TR studies, the non-periodic boundary condition model in the surface-normal direction, as shown in on atoms . After tperature ,39. The To elucidate the heat transfer mechanism across the interface, we investigated the vibrational density of states (VDOS) at the interfaces obtained from the Fourier transform of the interfacial atoms’ velocity autocorrelation .(1)P(ω)The thermal transport between graphene and Ti is mainly dominated by the phonon in the out-of-plane direction, and most of the phonon coupling is contributed by the low-frequency zone . The ove2 K, while the TBC of the thermal relaxation methods was 161 MW/m2 K. To elucidate the inner mechanism of the TBC diversity obtained from both the NEMD and TR methods, we calculated the phonon spectrum and the phonon coupling parameter, as shown in We first compared the TBC results obtained from both two methods, as shown in In addition, we analyzed the relationship between the phonon coupling strength and the TBC of different crystal faces. Since the results of NEMD were consistent with the thermal relaxation method, here we computed the TBC with different crystal faces using the TR method in 2 K at 250 K to 502 MW/m2 K at 450 K. It features an almost linear dependence relationship  for the Umklapp processes, which play the dominant role in heat conduction [We further explored the dependence of G on the environmental temperature, T, using the NEMD method for precise temperature maintenance and easy control. As shown in nduction . CorrespComparing the in-plane and out-of-plane phonon spectra with the different temperatures in 2 K (n = 1) to 63 ± 1 MW/m2 K (n = 5). This was due to the increasing thickness of graphene block, which enhanced the interfacial phonon scattering at the interface. Similar phenomena have been reported in heat transport across the graphene/Cu and graphene/Ni interfaces [We studied the TBC variation with graphene layers, N. The layer number of a graphene sheet can be controlled by CVD growth or physical translation. Here, the interfacial model of Ti(0001)/Gr model was employed and n represents the number of graphene layers, with the consideration of a few layers of graphene stacking in the experiment. The simulations were carried out by the NEMD method at 300 K, and the corresponding schematic model is shown in terfaces ,46. To e2 [The thermal conductivity and the TBC are sensitive to the conducted strain. Applying a cross-face strain is an effective method to tune the heat transport across the interface, as confirmed in the previous studies of graphene , MoS2 [42 , and bla2 . Here, w2 K, which is almost twice as high as the TBC in the strain-free state. However, the TBC was only about 48 MW/m2 K with the strain at 3%. The enormous TBC difference indicates that applying compressive strain to Ti and graphene is an efficient way to improve the TBC. In order to elucidate the strain effect on the TBC, we investigated the variation of phonon coupling strength under different strains. As shown in The compressive strain was found to enhance the thermal conductance, G, and followed an exponential dependence relationship, which is consistent with previous studies ,48. In FIn summary, the thermal boundary conductance at Ti/Gr interfaces was investigated systematically via MD simulations. Among the Ti(0001)/Gr, Ti(10-10)/Gr, and Ti(11-20)/Gr models, the Ti(0001)/Gr model exhibited the best performance of TBC at the interface and Ti(10-10)/Gr showed the lowest TBC value. The TBC increased with increasing temperature and its value increased 18.1% when the background temperature raised from 300 K to 450 K. The TBC decreased with increasing interfacial graphene layer numbers. A reduction of 85% was reported for an n-layer (n ≥ 5) graphene block compared with the case of a single-layer graphene interface. Our results exhibit enormous potential of Ti/Gr MMCs in thermal management and cooling applications.


WT) or mutant forms (ALS-causing TDP-43 mutations TDP-43A315T or TDP-43M337V). We then differentiated these NSC-34 lines into motoneuron-like cells and evaluated SG formation and disassembly kinetics in response to oxidative or osmotic stress treatment. Wild type and mutant TDP-43 appeared to be largely retained in the nucleus following exposure to arsenite-induced oxidative stress. Upon arsenite removal, mutant TDP-43 clearly accumulated within HuR positive SGs in the cytoplasm, whereas TDP-43WT remained mostly within the nucleus. 24 h following arsenite removal, all SGs were disassembled in both wild type and mutant TDP-43 expressing cells. By contrast, we observed significant differences in the dynamics of mutant TDP-43 association with SGs in response to hyperosmotic stress. Specifically, in response to sorbitol treatment, TDP-43WT remained in the nucleus, whereas mutant TDP-43 relocalized to HuR positive SGs in the cytoplasm following exposure to sorbitol stress, resulting in a significant increase in TDP-43 SG numbers. These SGs remained assembled for 24 h following removal of sorbitol. Our data reveal that under certain stress conditions the rates of SG formation and disassembly is modulated by TDP-43 mutations associated with ALS, and suggest that this may be an early event in the seeding of insoluble cytoplasmic inclusions observed in ALS.Amyotrophic Lateral Sclerosis (ALS) is characterized by degeneration of motor neurons in the brain and spinal cord. Cytoplasmic inclusions of TDP-43 are frequently reported in motor neurons of ALS patients. TDP-43 has also been shown to associate with stress granules (SGs), a complex of proteins and mRNAs formed in response to stress stimuli that temporarily sequester mRNA translation. The effect of pathogenic TDP-43 mutations within glycine-rich regions (where the majority of ALS-causing TDP-43 mutations occur) on SG dynamics in motor neurons is poorly understood. To address this issue, we generated murine NSC-34 cell lines that stably over-express wild type TDP-43 (TDP-43 Amyotrophic lateral sclerosis (ALS) is the most common adult-onset motor neuron disease. About 90% of patients exhibit sporadic ALS (sALS), whereas in ∼10% of familial ALS patients (fALS) a genetic cause has been identified, including mutations in the TDP-43 gene (trans-active response (TAR)-DNA binding protein 43 kDa) . Both spTDP-43 is predominantly localized to the nucleus where it mediates a variety of RNA processing functions , but canWT–EGFP, referred to as TDP-43WT), mutated hTDP-43 with methionine changed to valine at codon 337–fused to EGFP (hTDP-43M337V–EGFP), and mutated hTDP-43 with alanine changed to threonine at codon 315 fused to EGFP (hTDP-43A315T–EGFP), referred to as TDP-43A315T or TDP-43M337V thereafter. These mutations were generated by PCR amplification from a plasmid bearing TDP-43WT under the control of the C. elegans Punc-25 promoter. TDP-43WT-containing plasmid was used to make the two TDP-43 mutations M337V and A315T. The TDP-43 sequences (WT and mutated) within the Punc-25 plasmids/vectors were amplified by PCR using the forward primer with XhoI restriction site, and the reverse primer with BamHI restriction site from the Punc-25 plasmid , as verified by Sanger sequencing.The following TDP-43 expression constructs were made: wild-type human TDP-43 fused in frame to enhanced green fluorescent protein , NP-40, protease inhibitor cocktail tablet), incubated on ice (10 min), and centrifuged at 4°C at 1,000 × g for 10 min. The supernatant was collected as a cytoplasmic extract. The pellet was resuspended in Nuclear Lysis Buffer  Sodium Deoxycholate, 1 mM Sodium Fluoride, 2 mM Sodium Orthovanadate, 10% Glycerol, 1 mM PMSF, protease inhibitor cocktail tablets), incubated on ice for 15 min and centrifuged at 4°C at 16,000 × g for 10 min. The resulting supernatant was collected as a crude nuclear extract.Western blot was used to validate that TDP-43 clones selected by EGFP-based flow cytometry did indeed express similar levels of transfected TDP-43 see . In addiProtein extracts were loaded and electrophoresed on 12% SDS-PAGE gels and then transferred onto nitrocellulose membranes. The membranes were blocked with 5% non-fat milk in PBS with Tween 20 (PBST) at room temperature for 1 h, and incubated with rabbit anti-TDP-43 , mouse anti α-tubulin , JNK1/2 , phosphor (pT183/pY185)-JNK1/2 , GAPDH  or Lamin A/C  at 4°C overnight. After 3 washes with PBST, the membranes were incubated with anti-rabbit or anti-mouse HRP-conjugated secondary IgG  at room temperature for 1 h, followed by 3 washes in PBST. The proteins were visualized by WESTAR NOVA 2.0 . The image density of immuno-stained bands normalized to anti α-tubulin (loading control) was assessed using a Kodak image station 4000 MM  and Image J software . Whole b2 on round coverslips and maintained in growth medium containing Dulbecco’s modified Eagles Medium (DMEM) supplemented with 10% Fetal Calf Serum (FCS). After 24 h, when the cells were approximately 20% confluent, the culture medium was replaced with differentiation medium, consisting of DMEM/F12 supplemented with 0.5% FCS, 1% MEM Non-Essential Amino Acid  and 2 μM all-trans retinoic acid . After 5 days of differentiation, the cells were treated for 30 min with either sodium arsenite  at 0.5 mM or D-sorbitol  at 0.5 M, as per similar studies (n = 3).NSC-34 cells were seeded at 1,200/cm studies . Untreat® 488 donkey anti-goat , Alexa Fluor® 555 goat anti-mouse  each diluted at 1:500 in blocking buffer. The coverslips containing the immuno-stained NSC-34 cells were mounted with Prolong Diamond anti-fade medium containing DAPI , and placed on glass slides. Images were captured using a 63X Glycerol NA 1.3 objective mounted onto a Leica DMi8 SP8 Inverted Confocal microscope. Immuno-staining procedures and image exposure times were standardized between genotype for a given set of experiments. Resolution was set up at 1,024 × 1,024 DPI for bi-directional scanning. Pinhole size was set at 1. The gain per channel across all experiments was the same. Finally, image panels were assembled in Imaris software for analysis. Surface was created based on the cytoplasmic red signals for quantification of granule number and size. There were no changes to gamma settings, curves or input levels. The images were exported as TIFF files in Imaris. All TIFF image files were then imported into Adobe Photoshop  where only the brightness and contrast were uniformly adjusted across all panels. These adjustments did not obscure or remove any digital information present in the original raw images. Finally, all images and graphs were assembled and labeled in Adobe Illustrator  and converted into PDF figure files.After sorbitol or sodium arsenite treatment for 30 min or recovering from stress for between 1 and 24 h, the cells were rinsed twice with PBS, and fixed with 4% paraformaldehyde (PFA) in PBS for 10 min at room temperature. After rinsing 3 times in PBS, cells were treated with blocking buffer containing 2% bovine serum albumin (BSA) and 0.1% Triton X-100 for 30 min at room temperature. Cells were next incubated overnight at 4°C with primary antibodies HuR , TDP-43 , G3BP  and GFP  diluted in blocking buffer. Cells were washed 3 times with PBS for 5 min prior to incubation at room temperature with the appropriate Alexa-conjugated second antibodies for 1 h: Alexa Fluorcreate surface” tool was used, under “contour,” drawing mode “circle” was chosen, and the radium of 0.1 μm was set up for all the images to ensure the smallest SGs were included. As all the images were taken under the same settings, the brightness was not adjusted when analyzing. All the SGs were selected and surface was created. SGs number and size were automatically created. The number of SGs was indicated by total number of Surfaces. SG size was divided into three groups: less than 0.3 μm2 (≤0.3 μm2), greater than 0.5 μm2 (≥0.5 μm2), and between 0.3 and 0.5 μm2. 23–30 cells were analyzed per individual experiments. GraphPad Prism 8 software was employed to undertake all statistical analyses and to create the presented graphs. Multiple group analyses with single independent variables were performed by using one-way ANOVAs. To compare within groups, Dunnett’s multiple comparisons was used. P < 0.05 was considered as statistically significant. The Pearson’s correlation coefficient analyses were performed in Image J by using Colocalization Finder. The nuclei were removed and only the cytoplasmic granules were analyzed. The image channel was split and type was changed to 8-bit. Using “Colocalization Finder” plugin, the Pearson’s correlation was shown as “Pearson’s Rr.”The images were analyzed with Imaris software. To quantify SGs number and size, surface was created by the cytoplasmic red signals for granule number and size quantification. In Imaris the “WT, fALS-causing mutations TDP-43A315T, and TDP-43M337V, that were N-terminally tagged with Enhanced Green Fluorescent Protein (EGFP), or transfected with EGFP alone. Following antibiotic selection, single cell-derived colonies were picked, expanded, and assessed for EGFP expression by FACS. Cell lines with equivalent levels of EGFP expression  were largely retained in the nucleus prior to and following stress treatment (WT and endogenous TDP-43 (delineated by a difference in molecular weight from EGFP fusion) was predominantly retained in nuclear fractions. We did, however, note low amounts of exogenous and endogenous TDP-43 were present within cytoplasmic fractions following exposure to stress treatment . Interestingly, 3 h following arsenite removal, SGs in TDP-43WT expressing cells were almost disassembled  at 30 min SA treatment to large (≥0.5 μm2) size post SA treatment (1 h) across all genotypes (2) post SA treatment (1 h) became medium sized (3 h)  , suggestWT to SGs , followed by TDP-43M337V (∼8 SGs per cell) and TDP-43WT  TDP-43 expression level was similar to exogenous mutant TDP-43. This approach has allowed us to study the dynamics of mutated TDP-43 association with HuR and G3BP positive stress granule formation, and in particular, the transition to irreversible SGs; all of which is closer to being physiologically relevant in a differentiated motoneuron-like cell stably expressing low levels of exogenous TDP-43 across all genotypes. Further, our in vitro study provides for ease of tracking SGs compared to transgenic mice. We have shown that both WT and mutant TDP-43 were present in the nuclei, which was reminiscent of ALS patients who harbor TDP-43 mutations, but do not show symptoms until a later age . This has allowed us to make meaningful examinations and comparisons of SGs dynamics across our NSC-34 cells expressing WT or mutated exogenous TDP-43 over long periods of time in culture .The pathology/toxicity of TDP-43 leading to cell death is thought to occur when it translocates from the nucleus to the cytoplasm . In thisWhen we examined the expression of exogenous TDP-43, we found that endogenous TDP-43 expression dropped in the presence of exogenous mutant TDP-43 compared with exogenous wild type TDP-43. These observations are consistent with the findings by Xu et al. who reported that transgenic mice overexpressing mutant TDP-43 reduced the levels of endogenous mouse TDP-43 , supportIt is now recognized that TDP-43 is involved in SG pathways . Most stAn alternate explanation for why we did not observe WT-TDP-43 EGFP associating with SGs in the cytoplasm in response to stress, could be due to the design of the expression construct. For example, tagging with EGFP may in itself alter the protein interaction properties of TDP-43 and this may in turn affect its trafficking. We think this is unlikely for the following reasons: (1), we have demonstrated that WT-TDP-43-EGFP behaves the same as endogenous mouse TDP-43, namely most of it remains in the nucleus without stress, during stress, and immediately following removal of stress, and (2), the movements of mutant TDP-43 to SGs in the cytoplasm were not prevented despite employing the same expression construct and identical n-terminus fusion to EGFP. These mutant TDP-43-EGFP proteins are able to move in and out of the nucleus in response to stress, in a similar manner shown by previous researchers . A novelHow mutations in TDP-43 cause SG dynamic disruption is a key question in understanding the relationship between TDP-43 and SGs. Dewey et al. showed larger SG formation in TDP-43 G348C mutant expressing cells during osmotic stress treatment . Based oIn addition, we found subtle differences in the colocalization of mutant TDP-43 with SG markers that were dependent on the stress conditions investigated. Specifically, mutant TDP-43 was only partially colocated with G3BP in response to hyperosmotic stress compared to a close overlap with HuR under identical stress conditions. Interestingly, this difference was not observed in response to sodium arsenite. This indicates that different stressors selectively recruit proteins to SGs with different dynamics. SGs are comprised of diverse constituent proteins that include mRNA-binding proteins (HuR), proteins involved in mRNA metabolism (G3BP), translation-related factors and other signaling proteins unrelated to RNA metabolism . Given tOne characteristic feature of SGs is that they are transient structures, which are resolved upon the removal of stress . The ratBy contrast, when the same mutated TDP-43-expressing cells were treated with sodium arsenite, SGs containing mutated TDP-43 were present 1 h post removal of sodium arsenite, but had disassembled by 24 h. This maintenance of SGs containing mutated TDP-43 upon removal of osmotic stress, but clearance of such SGs upon oxidative stress, suggests that various stressors may play different roles in TDP-43 SG dynamics. It might also suggest that oxidative (sodium arsenite) and osmotic (sorbitol) stressors trigger distinct signaling pathways in SG assembly and disassembly, with some pathways resulting in more stable protein interactions with mutated TDP-43, an idea recently proposed by Hans and colleagues ; see alsWhile our results are most directly relevant to ALS with TDP-43 mutations, we believe that our findings may also be informative of cytoplasmic inclusions seeded by wild-type TDP-43. Our current study shows that when expressed at low levels, mutated TDP-43 is correctly localized in the nucleus under basal conditions similar to the wild-type protein . So the mutations in of themselves do not automatically result in cytoplasmic mislocalization/aggregation. Rather, mutant TDP-43 responses to stress  and recovery differ with subtle but important differences depending on the environmental stimuli. We suggest that this may be due to a degree of “stress loading” on neurons with one interpretation being that patient-identified mutations may accelerate or enhance the pathological process that would otherwise take time and repeated stress insults to manifest as mislocalization, aggregation or cellular toxicity, all of which give rise to interesting avenues for future investigations.The original contributions presented in the study are included in the article/PGN, DN, QD, EW, and MAH designed the study. PGN, QD, and DN wrote the original manuscript. PGN, DN, MAH, and EW edited the versions of the manuscript, contributed to the data analysis, and presentation. QD performed the experiments and analyses. JC and QD constructed the TDP-43 expression constructs under the supervision of MAH. EW supervised the clonal section and characterization of transfected TDP-43 NSC-34 cells. MJM assisted QD with Western blots. QD and PGN assembled the figures. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


The high-throughput technique of deep mutational scanning (DMS) has recently made it possible to experimentally measure the effects of all amino-acid mutations to a protein . Over thdms-view (https://dms-view.github.io/), a flexible, web-based, interactive visualization tool for DMS data. dms-view is written in JavaScript and D3, and links site-level and mutation-level DMS data to a 3-D protein structure. The user can interactively select sites of interest to examine the DMS measurements in the context of the protein structure. dms-view tracks the input data and user selections in the URL, making it possible to save specific views of interactively generated visualizations to share with collaborators or to support a published study. Importantly, dms-view takes a flexible input data file so users can easily visualize their own DMS data in the context of protein structures of their choosing, and also incorporate additional information such amino-acid frequencies in natural alignments.Here we describe dms-view at https://dms-view.github.io. The tool consists of a data section at the top and a description section at the bottom. The data section displays the user-specified data in three panels: the site-plot panel, the mutation-plot panel, and the protein-structure panel  for the human sera condition “Age 21 2010” to highlight them on the protein structure.In https://dms-view.github.io.dms-view is available at https://github.com/dms-view/dms-view.github.io.Source code is available at https://dms-view.github.io/docs) and case studies (https://dms-view.github.io/docs/casestudies/) are also available.Documentation (


Few studies have explored outdoor therapy when facilitated by clinical psychologists within an inpatient mental health service. In the present study, outdoor psychology sessions were introduced after service users (SUs) expressed a desire to return to face-to-face working during the COVID-19 pandemic. This study aimed to explore SUs’ and clinical psychologists’ perspectives on the feasibility of conducting outdoor therapy within the service. A mixed-method approach was underpinned by critical realist philosophy. Three psychologists maintained reflective diaries following outdoor therapy sessions with 16 SUs. A subsample of 14 SUs completed scales measuring therapeutic alliance and comfort during outdoor sessions. A subsample of eight SUs participated in semi-structured interviews. Data was analysed using descriptive statistics and thematic analysis. Quantitative and qualitative data demonstrated high SU satisfaction with therapeutic alliance and comfort outdoors. Six themes were identified: utilising a person-centred approach; the value of multi-disciplinary team support; enhancing therapeutic engagement; the benefits of time away from the ward; managing confidentiality; physical health and safety. This feasibility study demonstrated the introduction of outdoor psychology sessions within an inpatient mental health service to be a viable response to COVID-19. The findings suggest outdoor therapy can be an effective and safe mode of therapy, and can offset the challenges of indoor working, providing certain risk factors are considered and managed. The limitations of this study and implications for clinical practice are discussed. Further research is now required to support future integration into clinical practice. According to the biophilia hypothesis, humans have an innate need for contact with nature to achieve satisfaction and meaning in multiple areas of their lives . Nature Nature-based interventions, such as horticultural therapy, gardening, and the Japanese practice of Shinrin-yoku (“forest bathing”), have received increased attention internationally and are being introduced as methods of treating ill mental health . TalkingAdult inpatient mental health rehabilitation services in the United Kingdom aim to support individuals with complex and enduring mental health difficulties to develop the emotional, practical and social skills needed for successful community reintegration and independent living . The COVThe present study took place across two inpatient units, with 40 open ward beds and eight high dependency unit beds, within an NHS adult inpatient mental health rehabilitation service located in central England. Prior to the COVID-19 pandemic, talking therapy was predominantly held indoors, with occasional outdoor sessions based on patient need . During the COVID-19 pandemic, the Clinical Psychology department initially moved to offering digital therapy. However, anecdotal evidence from SUs suggested many individuals found phone sessions were not as effective as face-to-face working. After identifying empirical evidence that highlighted the benefits of taking therapy outdoors, the team began to offer outdoor psychology sessions in line with the aforementioned BPS guidance. Given the lack of prior research in public healthcare settings and the novelty of offering more routine outdoor therapy within the present service, a feasibility study was conducted to explore the impact of this change in practice for both SUs and psychologists.Two clinical psychologists and one trainee clinical psychologist from the rehabilitation service participated in the study and conducted outdoor sessions with 16 SUs . Research has mainly investigated the reliability and validity of the SRS with outpatients, university students and couple/family client groups, with the SRS demonstrating moderate to high internal consistency (α ranged from 0.70 to 0.97), good test-retest reliability (r ranged from 0.54 to 0.70) and low to moderate concurrent validity  or over the phone (n = 2). With SUs’ consent, answers were written verbatim by the interviewer and were regularly reviewed with the SU during the interview to ensure the content correctly captured their experience.After engaging in at least one outdoor psychology session, SUs were invited to participate in a semi-structured interview about their experience. Interviews lasted between 30 and 45 min, depending on the time needed to gain an understanding of a SU’s experience. Interviews were conducted by a psychologist that was not the SU’s regular psychologist. Interviews were held either face-to-face  and were “keen to have outdoor therapy due to the longer appointment time” (Psychologist [P] 3). Although, this was noted to be a compromise for one SU who wanted to return to face-to-face working but did not have a desire to meet outdoors. For other SUs being outdoors and physically active was important to them and therefore outdoor working was “in line with their personal preference and values” (P3). Additionally, spending time outdoors was part of some SUs’ rehabilitation goals  and therefore was integral to their psychology intervention .Decisions around whether outdoor sessions should include sitting or gentle walking  were informed by SUs’ risk assessments, formulations and preferences. For example, “knowing this person’s formulation, having sessions where I was required to push [their] wheelchair for longer distances…would be psychologically challenging for [them]. Therefore, I did not suggest walking sessions, just outside sat down sessions” (P1). The intended objectives of a session also contributed to the choice of activity .The extent the natural environment was incorporated into sessions varied according to SU need. Some sessions used the natural environment as a backdrop, with observations about the surroundings sometimes spontaneously being commented on in conversation. On other occasions, the environment was actively used during the session to support SUs to manage their distress or engage in relaxation techniques as part of an intervention .Psychologists discussed reviewing how sessions were progressing and re-contracting if necessary. For example, “We agreed that if they… felt uncomfortable at all, they would let me know so we could review how to manage these situations” (P3). This highlighted how psychologists attempted to ensure a collaborative approach was maintained throughout the outdoor therapy process.Both psychologists and SUs highlighted the importance of continued multi-disciplinary team (MDT) working throughout the planning and facilitation of outdoor therapy. In an inpatient context, it is a legal requirement that SUs on a mental health section have the appropriate leave to engage in activities off the ward. Further, thorough risk assessments to ensure it is safe for SUs to engage in outdoor sessions must be conducted. This involves the collaboration of the MDT, including psychologists, consultant psychiatrists, nurses, and occupational therapists, and was reported by psychologists as crucial in the planning process.Multi-disciplinary team members assisting SUs to go outdoors in between psychology sessions also built SUs’ familiarity with an outdoor setting and made the facilitation of outdoor therapy more feasible . Psychologists noted having “someone available to call [on the ward]” (P1) was reassuring and helpful in the event any risks arose during a session. One SU also shared “another member of staff from the ward came on the walk too because I was on escorted leave” (SU2). This highlights how the accessibility of colleagues during sessions also supported the safe facilitation of outdoor therapy.Outdoor sessions promoted engagement in psychology through increased sense of freedom, self-regulation and mutuality in the therapeutic relationship. SUs reported psychology sessions in a clinic room as “too official” (SU5) and that having “nowhere to look” (SU2) heightened anxiety. The noise and disturbances on the ward were described as distracting, which made it difficult to engage in sessions.In contrast, SUs reported having their psychology sessions outdoors helped them experience a sense of freedom and was “good for my anxiety” (SU3). The natural environment was repeatedly cited by SUs as supporting them to feel relaxed and safe, particularly being in the fresh air and “noticing the wildlife” (SU2). SUs reported “the ability to breathe easier” (SU8) outdoors, which helped them “think more clearly” (SU4) and made it easier to express themselves and talk to their psychologist.Psychologists noted that several SUs seemed to find freedom of movement outside helpful to self-regulate during sessions. This was beneficial for SUs who felt restricted when having to sit during sessions and who found engaging in emotive conversations particularly challenging .In comparison to indoor sessions, SUs also described outdoor psychology sessions as being “easier to talk side on, less overwhelming, less eye-contact.” (SU1) and “I was able to vape, which gave me something to do and time to pause and gather my thoughts, rather than having an uncomfortable, awkward silence.” (SU2). This suggests SUs felt less pressure to comply with social expectations during outdoor sessions, which supported them to feel more comfortable in the company of their psychologist.Several SUs described how being in an outdoor setting positively impacted their therapeutic relationship with their psychologist, including that it felt more “friendly and respectful” (SU5). Psychologists recognised that the more informal outdoor setting was “great in many ways because it reduces the barrier between “patient” and “staff” and helps input to feel more collaborative” (P1). However, the informal setting was also reported as a risk factor that might unintentionally give SUs the impression that the relationship was more friendship-based than therapeutic. Therefore, this was considered important to hold in mind and actively monitor during outdoor sessions.Service users were often enthusiastic about having outdoor sessions and expressed enjoyment in having an opportunity to leave the ward. It was noted by SUs that “if you’re boxed into a place you can get claustrophobic” (SU6), but “once you’re out of the unit, it’s like a weight has been lifted temporarily… It’s nice not being in the pressure cooker of a hospital” (SU2). Psychologists also reflected how they felt more relaxed being away from the hospital and comfortable facilitating sessions outdoors .The inpatient ward were described as highly emotive and unpredictable environments, which is compounded by SUs complex and varying needs. One psychologist noted that leaving the ward may enable SUs to discuss incidents that occur on the ward more easily: “There had been a distressing incident on the ward the night before… I think being away from the ward helped when discussing this.” (P3). This, in turn, may provide more opportunity to process such events.Outdoor sessions were also helpful in supporting SUs who found being outdoors anxiety provoking to begin to regulate their anxiety. Some SUs shared that having an opportunity to leave the ward with their psychologist contributed to building their confidence being outside and how this supported them toward discharge . One psychologist described noticing a difference in SUs’ tolerance of being outdoors: “We went further than the previous two sessions” (P1). Another SU reported having continued to go on regular walks as outdoor sessions had “re-sparked my love of nature and wanting to be outside” (SU1).One of the challenges identified during outdoor sessions was maintaining SUs’ confidentiality due to the potential for other people to be present within the outdoor space. SUs had contrasting opinions around how to manage confidentiality during outdoor sessions. Some SUs reported experiencing worry about whether therapeutic conversations would be overheard and contracted with their psychologist that they would pause the conversation when others were in earshot. These concerns included SUs who required 2:1 escorted leave, which made creating a private therapy space outdoors even more challenging. For example, one SU said that having an additional staff member accompany them and their psychologist “made me a bit more self-aware, paranoia would kick in, I asked my psychologist ‘is he going to think any different of me?”’ (SU2); implying this arrangement was at times distressing and distracting for the SU. However, managing confidentiality can also be challenging during indoor sessions when SUs require 2:1 observations as members of the nursing team are also present during psychology sessions.In contrast, other SUs advised they did not mind their conversations being overheard, therefore handing responsibility over to the psychologists to monitor appropriate levels of privacy . Psychologists’ phrasing of questions was also reported by SUs to help ease their worries about their confidentiality being maintained.Stopping therapeutic conversations to maintain privacy was identified to have benefits and challenges. One psychologist stated “we engaged in problem-free talk which was a helpful opportunity to bring humour into the session and build rapport” (P3). Another psychologist reported the pauses gave a SU time to think carefully about their response to a question. The main challenges identified by psychologists were that pausing disrupted the flow of conversation and other people’s presence made sessions feel less private. Conversely, SUs expressed frustration that “people keep earwigging and wanting to hear what you are saying” (SU6) when having sessions on the ward. Therefore, outdoor sessions felt “a little more private than someone walking past the door” (SU8).Having the opportunity to exercise was highlighted by SUs and psychologists as a physical health benefit to having sessions outdoors. A SU also shared they “felt a bit docile that morning because of my medication but being outdoors helped wake me up” (SU1). This suggests outdoor sessions can support SUs to manage medication side effects. However, when less physically active outdoor sessions needed to be facilitated, such as for SUs with less physical mobility, psychologists found there were limited seating areas on the hospital grounds that were comfortable and private, thus reducing the choice of locations. In some cases, sessions were finished indoors where appropriate seating was more readily available.The weather also presented physical risks to outdoor working, such as slipping on wet and muddy ground and SUs not wearing skin protection in the sun. One psychologist expressed concern for their own wellbeing “as I have a physical health condition that deteriorates when I am cold” (P1). One SU shared “the pollen didn’t get to my nose and make me sneeze” (SU1). However, this raised a valid issue that those who have hay fever may experience more discomfort outdoors when the pollen count is higher. The need for appropriate equipment on the ward to maintain staff and SU safety in all types of weather was emphasised: “It made me think about the things we will need to be safe outside . We don’t always have these things in the workplace” (P2). At times, low temperatures, rain and inappropriate clothing led to outdoor sessions being moved indoors.In line with COVID-19 physical distancing guidance at the time of the study, psychologists and SUs needed to maintain a two-metre physical distance from one another. This physical distance was problematic at times, such as on one occasion when a psychologist had to walk in the road due to narrow pathways. Busy traffic also presented another physical hazard, particularly when SUs’ and psychologists’ walking speed was different. This resulted in psychologists and SUs occasionally misjudging the time needed to safely cross a road .Outdoor psychology sessions were introduced within an inpatient mental health rehabilitation service following anecdotal feedback from SUs that phone sessions were not as effective as meeting face-to-face during the COVID-19 pandemic. Given the lack of prior research in public healthcare settings that investigate the barriers and facilitators to outdoor practice, this study aimed to explore SUs’ and clinical psychologists’ perspectives on the feasibility of this change in practice as a response to COVID-19.Qualitative feedback from SUs supported the SRS mean score ratings which suggested high satisfaction in both therapeutic alliance and comfort outdoors. However, some SUs did at times rate lower satisfaction levels. Lower levels of satisfaction were observed to usually be rated by SUs who were engaging in outdoor therapy as part of a Cognitive Behavioural Therapy exposure intervention. This suggests there is a strong clinical need for outdoor sessions to be considered even with SUs who may experience discomfort.Service users’ enthusiasm for going outdoors and relief in having time away from the ward reflected previous research where inpatients expressed a desire for more opportunities to go outside . The expDue to the unpredictability of outdoor working, risks and practical issues were identified during outdoor sessions. These included challenges in maintaining confidentiality and relational boundaries, and keeping physically safe in different types of weather and environments. These risks were cited to occasionally disrupt outdoor sessions, but were not reported to be overly hindering and were usually manageable within sessions. Using a person-centred approach and working alongside the MDT was recognised as essential in supporting the feasibility of safe and effective outdoor sessions. Collaborative working allowed for potential risks and SU needs and preferences to be identified, managed and reviewed throughout the course of outdoor therapy. This way of working likely supported SUs to feel comfortable in an outdoor setting and experience satisfaction in the therapeutic alliance, as suggested by SUs’ SRS mean score ratings. Therefore, with regular risk assessments it is likely risks can be effectively minimised, as outlined in the BPS guidance .Findings specific to the client group were also identified. Outdoor sessions were cited to support SUs to manage side effects of medication and build confidence being outdoors for SUs engaging in exposure interventions and other types of therapy. These are important elements in supporting SUs’ progress toward community reintegration. Having organisational processes in place such as leave requirements are also unique to inpatient services and presented a novel barrier to outdoor working. These findings have not been highlighted in previous research and therefore add to the literature and need to be considered in clinical practice when working with this population.Service users were interviewed by a psychologist who was not their regular psychologist in an attempt to minimise bias and demand characteristics. However, SRS were completed with SUs’ regular psychologists during therapy and therefore may have influenced the validity of SUs’ responses. Further, SRS scores must be interpreted with caution as the psychometric properties of the SRS were tested using community samples and therefore are not necessarily generalisable to the client group of this study. The need for further research to investigate the validity of the SRS with more specific clinical populations has been highlighted .The findings of this study have been collected solely from SUs who participated in outdoor therapy. This is likely to have resulted in the participants’ views of outdoor working intrinsically being more positive than those who declined outdoor sessions. The reasons for SUs opting out of outdoor therapy were not explored in this study, nor were the organisational factors that prevented participation . Future research is warranted that explores these factors to gain a more multifaceted understanding of the facilitators and barriers within inpatient services.This study supports previous research suggesting person-centred therapy includes an openness toward alternative therapy environments (see “environmental safe uncertainty”; This feasibility study concluded that outdoor psychology sessions were a viable response to the COVID-19 pandemic within an NHS adult inpatient mental health rehabilitation service. Outdoor therapy was described as a beneficial experience for both SUs and psychologists, with SUs further reporting high satisfaction in therapeutic alliance and comfort outdoors. This provides evidence for the continuation of outdoor therapy as a treatment option within the service, provided effective risk assessment and management is conducted throughout the course of therapy.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by Leicestershire Partnership NHS Trust WeImproveQ. The patients/participants provided their written or verbal informed consent to participate in this study.KK, KF, and SC contributed to the research question generation and designing of the methodology and created the study documents including the bespoke interview schedules. KK and KF submitted the project for approval with the appropriate committee. KK, KF, and GJ identified service users who met the inclusion criteria to complete session rating scales and interviews. GJ and KK completed interviews and maintained a record of the completed session rating scales and diaries. GJ led the analysis which was reviewed by KK, KF, and SC. GJ wrote, revised and synthesised revisions of the manuscript from KK, KF, and SC. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Graphene‐based moiré heterostructures are strongly correlated materials, and they are considered to be an effective platform to investigate the challenges of condensed matter physics. This is due to the distinct electronic properties that are unique to moiré superlattices and peculiar band structures. The increasing research on strongly correlated physics via graphene‐based moiré heterostructures, especially unconventional superconductors, greatly promotes the development of condensed matter physics. Herein, the preparation methods of graphene‐based moiré heterostructures on both in situ growth and assembling monolayer 2D materials are discussed. Methods to improve the quality of graphene and optimize the transfer process are presented to mitigate the limitations of low‐quality graphene and damage caused by the transfer process during the fabrication of graphene‐based moiré heterostructures. Then, the topological properties in various graphene‐based moiré heterostructures are reviewed. Furthermore, recent advances regarding the factors that influence physical performances via a changing twist angle, the exertion of strain, and regulation of the dielectric environment are presented. Moreover, various unique physical properties in graphene‐based moiré heterostructures are demonstrated. Finally, the challenges faced during the preparation and characterization of graphene‐based moiré heterostructures are discussed. An outlook for the further development of moiré heterostructures is also presented. This review presents the preparation and optimization of graphene‐based moiré heterostructures, including twisted bilayer graphene, twisted trilayer graphene, twisted double bilayer graphene, graphene/ hexagonal boron nitride, and graphene/transition metal dichalcogenides. The topological properties and correlated physical performances are comprehensively illustrated. A clear understanding of the mechanism regarding many‐body physics will be a breakthrough for condensed matter physics. Apart from graphene, 2D materials, such as hexagonal boron nitride (h‐BN) and transition metal dichalcogenides (TMDCs), have been extensively researched, owing to their excellent electronic properties or intrinsic magnetic order. Additionally, these 2D materials may be used to fabricate vertical van der Waals (vdW) heterostructures, owing to the weak vdW interactions between layers. The unique and engineered structures of vertical vdW heterostructures with diverse physical properties benefited research on condensed matter physics. Now, graphene‐based moiré heterostructures, which are formed by stacking bilayer graphene (BLG), multilayer graphene, or graphene with other 2D materials, are the representative vertical vdW heterostructures. Graphene‐based moiré heterostructures exhibited topological properties caused by a moiré superlattice and various correlated states, which are introduced by strong electron–electron interactions. Since the discovery of unconventional superconductivity, correlated insulator behavior in magic‐angle bilayer graphene (MATBG) and the transition from insulation to superconductivity were simply realized. Thus, graphene‐based moiré heterostructures were introduced to the field of strong correlation physics, thereby enabling research on unconventional superconductivity. Inspired by these discoveries, there is an upsurge in the study of twisted trilayer graphene (tTLG), twisted double bilayer graphene (tDBG), twisted graphene/h‐BN, and twisted graphene/TMDCs heterostructures. That is, the studies on graphene‐based moiré heterostructures triggered significant passion of researchers.The discovery of graphene with superior physical, perfect optical, and unique electronic properties has triggered extensive interest in the field of condensed matter physics.1 As t and self‐assembly via stacking or folding monolayer 2D materials. However, neither method can be perfectly implemented. The in situ growth method represented by chemical vapor deposition (CVD) cannot produce graphene‐based moiré heterostructures with a precisely controlled twist angle. The self‐assembling characteristic of 2D materials enables a more precise twist angle; however, it is easy to introduce contamination, wrinkles, and polymer residues during the transfer process. One method to fabricate high‐quality graphene‐based moiré heterostructures is to develop an effective CVD growth method by regulating the growth conditions; another way is to optimize the assembling process. Extensive research was conducted on assembling because it is currently the most feasible method; this included optimizing the transfer process to reduce unnecessary damage and improving the quality of graphene to decrease surface contamination. Clearly, it is difficult to precisely control the twisted moiré structures, which hinders the rapid progress of graphene‐based moiré heterostructures. Therefore, we summarize existing preparation methods to provide a guide for the development of graphene‐based moiré heterostructures.Currently, the preparation methods of graphene‐based moiré heterostructures include in situ growth19 and the quantum anomalous Hall effect in twisted bilayer graphene (tBLG), the Mott insulator in ABC‐TLG, the ferromagnetism in tDBG, the Pomeranchuk effect in MATBG, the ferroelectricity in BLG/h‐BN, and the exciton effect in graphene/TMDCs heterostructures. A few reviews on the physical properties and applications have been reported; however, they are primarily focused on tBLG and TMDCs vdW heterostructures. Currently, there was no review on the systematic description of moiré patterns appearing in heterostructures. Moreover, various newly discovered physical properties in graphene‐based moiré heterostructures have not been systematically summarized. The preparation, quality improvement and topological properties of graphene‐based moiré heterostructures and the factors that influence their physical properties, such as twist angle, strain, and dielectric environment, lack detailed descriptions in the literature. Herein, we first present the preparation methods used for graphene‐based moiré heterostructures; this includes in situ growth and assembling using monolayer 2D materials. Subsequently, we address the limitations of the preparation methods by discussing and summarizing how to optimize the transfer process and improve the quality of graphene. Further, topological properties are discussed to present various moiré patterns and corresponding energy band structures. Moreover, the factors that influence the physical properties of graphene‐based moiré heterostructures are presented, and they more precisely tune the performance. Meanwhile, the typical performance of superconductivity, the correlated insulator and various newly observed properties are systematically introduced; these include the quantum anomalous Hall effect, ferromagnetism, ferroelectricity, the Pomeranchuk effect, and tunable excitons. Finally, we summarize the development of twistronics based on graphene‐based moiré heterostructures, including the development limitations in fabrication, characterization, and a deep investigation into the mechanism of many‐body physics.In addition to the preparation of graphene‐based moiré heterostructures, many recent studies focused on the observation of their topological and correlated properties, such as, the existence of a moiré superlattice and topological minibands,25 the2 TLG, tDBG, and graphene/X . In the field of artificial graphene‐based moiré heterostructures, the most important process is the effective preparation of moiré superlattices with specific alignment. According to the processes, the preparation methods can be divided into two categories: in situ growth and assembling of monolayer 2D material. In this section, a detailed introduction on the preparation method of graphene‐based moiré heterostructures is presented.Graphene‐based moiré heterostructures consist of BLG, multilayer graphene or graphene flakes, and other 2D materials with weak vdW forces between the layers, such as tBLG,36 TLG2.1 Thus, the key to the research of novel physical properties in graphene‐based moiré heterostructures is precise preparation. The in situ growth method, without the aid of a transfer process, enables high quality products and avoids the introduction of impurities and wrinkles. In situ growth includes CVD and epitaxial growth. Recently, there were many competing studies on the preparation of graphene‐based moiré heterostructures via CVD, owing to the many advantages of this method, such as the high cleanliness and feasible transfer, which benefits research on intrinsic performance in more depth. As an example, it is difficult to grow TLG on Cu foils using the CVD method, owing to the low amount of dissolved carbon and self‐limiting growth. Moreover, the carbon solubility on Ni is larger than that on Cu, and the carbon may be completely dissolved in the Cu/Ni alloy under suitable conditions  showed perfect consistency between experimental and theoretical calculations  and graphene. In the stage of nucleation, the graphene/Cu step interface determined the graphene orientation. Moreover, the second layer started to nucleate with the carbon atoms diffused underneath the graphene edge. In this method, the number of layers and morphology were controlled by the thermodynamically dominated nucleation and kinetically regulated growth, which enabled the in‐situ preparation of graphene‐based moiré heterostructures.Although the above‐mentioned CVD‐grown graphene‐based moiré heterostructures have many advantages, it is difficult to accurately tune the interlayer twist angle between different 2D materials. The fundamental reason is that there is interlayer interaction during the CVD growth process. To decrease the interlayer coupling, tBLG was fabricated on Cu (111) via a designed two‐step epitaxial growth process Figure .18]18 was spin‐coated on MoS2 and then exposed to ultraviolet/ozone to increase its interfacial adhesion. Finally, Cu was placed on TPN to grow graphene via CVD. Consequently, a high‐quality moiré graphene/MoS2 heterostructure was fabricated with the assistance of TPN and a Cu substrate. The preparation process of graphene/TMDCs heterostructures in the abovementioned case enhanced the adhesion of the interface, thereby significantly improving the electrical performance of the device based on this heterostructure. However, TPN residue may exist in the interface between graphene and MoS2, which affects the quality of the moiré graphene/MoS2 heterostructure.Briefly, the direct CVD preparation of graphene/MoSs Figure .54]542 he2 after the growth of graphene  tip, the folding line selection is arbitrary and relies on whether there are cracks in the graphene sheet  tip  mold, and an epoxy or PDMS droplet deposited onto the substrate to improve the adhesion  wafer, and a gold pattern was then fabricated on the as‐grown MLG. The most important factor was that annealing in H2 could reduce the adhesion between graphene and the Ge substrate. Thus, the graphene flake was picked up facilely, and tBLG was precisely fabricated by stacking single‐layer graphene. The selected area electron diffraction pattern of the tBLG exhibited a twist angle of 12°. This result indicates that the pick‐and‐place method is feasible  is an essential and crucial step, which, to a large extent, determines the quality of the transferred graphene. Consequently, the transfer process is crucial for obtaining high‐quality graphene‐based moiré heterostructures to widen its application. After a decade of research on graphene transfer, the transfer method is now divided into dry and wet transfer; both methods have their own advantages and disadvantages. Next, we introduce these methods in detail. The transfer process is illustrated as follows  to transfer graphene from a Ge (110) substrate to different substrates, owing to the weak interaction between graphene and the Ge (110) substrate.70 The To address these issues, support layers made by other polymers have been attempted. For example, the adhesive bisbenzocyclobutene (BCB) benefited the transfer process of 2D materials. The transfer process from the growth substrate to the target wafer is depicted as follows . However, the PMMA‐assisted process engenders some issues that severely degrade the quality of graphene: polymer contamination and graphene wrinkling.71 To s Figure . First, s Figure , multilas Figure . However The copper substrate had a rough surface during the annealing and growth process at a high temperature; therefore, the transferred graphene supported by the polymer layer did not lie flat on the target substrate after removing the copper foil. Small gaps were generated in the interface, which caused an incomplete contact between the graphene and target substrate and unavoidably caused cracks and tears when the polymer layer was removed. The shallow wells reduced the surface tension via heating to obtain high‐quality target materials.Suk et al. proposed a novel transfer technique to improve the transfer of CVD‐derived MLG grown on a copper substrate onto shallow wells to avoid trapping water and decrease the destruction when removing the support layer Figure .78]78e Figure .[89] To investigate the role of electron–electron interactions, superconducting tBLG‐based devices with different h‐BN thicknesses were fabricated. In these devices, the Coulomb interactions could be screened to a large degree with the varying thickness of h‐BN. For example, the superconducting tBLG devices 1 and 2 had an identical twist angle of ≈1.08°; however, the thickness of the h‐BN was one order of magnitude different . Although both the devices exhibited similar superconducting transition temperatures, device 2 presented a correlated insulating state with an activation gap that was half as wide as that of device 1 , the excitations of correlated states were polarized, and charge conduction then occurred when the Zeeman energy gμBB was equivalent to the charge gap. Inspired by this model, tuning correlated properties has attracted wide interest.Graphene‐based moiré heterostructures, such as MATBG, exhibit strong electron−electron interactions, which result in flat energy bands near the zero Fermi energy and cause a series of correlated phenomena.164 Co Notably, there was a transition from metal to superconductor with a decrease in temperature at B⊥ = 0 T. As the magnetic field increased, the correlated insulator transitioned to a metal phase, owing to the increase in the Zeeman field, and the superconductor transition temperature Tc reached 1.7 K at the finite twist angle and carrier density.The transfer process was optimized to reduce the relaxation of the twist angle to realize superconductivity at higher temperatures. Although a series of superconducting domes were observed at a similar carrier density, the superconductor transition temperature Tc was almost 3 K higher than previously reported (Tc = 1.7 K)  Figure .[21]y Figure , strongld Figure .1 Figure ,[27]n Figure .[1781 Figure .[27]5.2.5 light absorption, and optical nonlinear effects in semiconductors; thus, the exciton effect plays a vital role in optical properties. Despite practical interest, it is difficult to observe excitons. Graphene‐based moiré heterostructures are a class of materials with a continuously tunable bandgap and pseudospin texture, which provide a platform for the observation of excitons. For example, electron−hole pairs were generated in the h‐BN‐encapsulated BLG moiré heterostructures under incident light, which resulted in a photocurrent with two absorption peaks that were proportional to the optical absorption (Figure  These photocurrent peaks shifted to higher energies as the bandgap increased, owing to the application of D (Figure  In addition to the regulation of the exciton state by D, the layer‐asymmetric strain also had a significant influence on this effect because the strain assisted the formation of the energy gap. When strain was evident in tBLG, the electron−hole symmetry was broken and the Dirac points shifted in energy (Figure  In the MATBG system, the bandgap between the valence band and the conduction band widened with increasing strain (Figure  Moreover, the exciton effect also appeared in the graphene/TMDCs, such as graphene/MoS2, which showed that the exciton absorption is dependent on the twist angle. As the twist angle increased, the interlayer coupling declined. Correspondingly, the exciton formation process was promoted to facilitate exciton absorption, owing to the decreasing interlayer electron transfer (Figure 2. Additionally, the exciton lifetimes also exhibited a significant difference when the stacking order of graphene and TMDCs was varied. From transient absorption spectroscopy, the exciton lifetime of the WSe2/grapheneIn addition to the generation of the Pomeranchuk effect, the changing of electronic behaviors also produces excitons. Excitons are the bound states of an electron and a hole in semiconductors, which are generated by exciting an electron from the full valence band to the empty conduction band to form a tightly bound electron−hole pair. The exciton effect has an important influence on physical processes, such as photoluminescence emission,182 liD Figure , which ry Figure , which in Figure , which fr Figure , where a2 heterostructure (Figure  To summarize, the exciton effect has been observed through the variation of the photocurrent in graphene‐based moiré heterostructures, which has a significant influence on the optical properties. The exciton formation process and lifetime rely on the structure of graphene‐based moiré heterostructures, such as the twist angle and the stacking order of different layers. These results enrich the understanding of the exciton effect in graphene‐based moiré heterostructures, which provides significant guidance toward designing optoelectronic devices.heterostructure Figure  was conse Figure , owing t (Figure 186 To6In the field of condensed matter physics, graphene‐based moiré heterostructures have been extensively studied as a promising platform to implement the regulation of moiré pattern and energy band structures and the observation of correlated phenomena. In particular, the realization of a superflat miniband and the transition between correlated insulator states and superconductivity promotes the development of twistronics.Herein, we have presented the discovery and development of various topological performances and correlated physical properties in graphene‐based moiré heterostructures. The foundation of this system is the effective preparation of graphene‐based moiré heterostructures. We have briefly described fabrication methods, including in situ growth and the assembling of monolayer 2D materials. Then, we summarized the methods that may be used to enhance the quality of graphene‐based moiré heterostructures, including the optimization of the transfer process and improvement of graphene quality. Finally, the introduction of properties and influence factors enable further research on condensed matter physics.h‐BN and graphene/MoS2. Second, it is difficult to fabricate high‐quality graphene‐based moiré heterostructures on a large scale, owing to the difficulty in controlling the twist angle. Moreover, the assembly method inevitably affects the performance of graphene‐based moiré heterostructures, owing to the transfer process and mechanical regulation of the twist angle, which results in a low yield of the heterostructures. Recent advances in the fabrication of graphene‐based moiré heterostructures enable high controllability over the stacking order. It is believed that full control of the twist angle may be achieved in the near future.Despite the significant progress reviewed herein, it should be noted that some crucial challenges limit the progress of graphene‐based moiré heterostructures. For example, it is difficult to achieve high‐quality graphene‐based moiré heterostructures via in situ growth or assembly. The control of the twist angle is not precise in in situ growth, and the promising method of the assembling process causes serious tearing, wrinkles, and/or interface polymer residues, which directly limits in‐depth research on the physical properties of these heterostructures and their effective applications to optoelectronic devices. There are additional problems regarding the preparation methods. First, the preparation of tBLG with a specific twist angle may be achieved using CVD; however, there are challenges in directly achieving graphene‐based moiré heterostructures composed of different 2D materials, such as graphene/ Graphene‐based moiré heterostructures must undergo extensive characterization before device application and physical performance exploration, such as TEM, STM, and AFM. The direct characterizing of the moiré pattern using TEM requires the samples to be placed on a dedicated TEM grid, which is destructive to the sample. STM may use the probe tip to produce an image of the moiré superlattice; however, the characterization requires the sample to be conductive, which prevents it being packaged by h‐BN. Similar to STM, the AFM tip is in contact with the graphene‐based moiré heterostructures, and it requires no top packaging or top gates, which limits device applications. Therefore, it is essential to improve the characterization methods and particularly develop the in situ characterization of moiré superlattices in graphene‐based moiré heterostructures, which may be of great significance.In addition to fabrication, the characterization of graphene‐based moiré heterostructures is also a challenge that affects its potential applications.187 Grh‐BN/graphene/h‐BN with slight misalignment between its layers behaves similarly to two interfering moiré patterns, which generates a lattice and electronic spectrum reconstruction. Additionally, graphene encapsulated by h‐BN can cause electrons to scatter, which leads to spectral changes at arbitrarily low energies; this is beneficial for controlling the properties of 2D materials. Stacking two layers of TMDCs with a specific angle to engineer flat bands may realize insulating and superconducting states, which provides a platform to exploring other electronic phases such as exciton condensates and spin liquids. The moiré heterostructures composed of h‐BN and TMDCs may be applied to investigate correlated electronic states and may also be used as spectroscopic tools to study interaction‐induced exciton‐polarons. Graphene encapsulated by hexagonal h‐BN and slightly misaligned with the top and bottom h‐BN layers experiences two interfering moiré patterns, which results in a so‐called supermoiré. Recently, extensive research has been conducted on graphene‐based moiré heterostructures to understanding many‐body physics; however, the mechanism of the superconducting phase remains unclear. It is believed that the investigation of graphene‐based moiré heterostructures will provide rich research opportunities in the near future.The opportunities and challenges are always in coexistence. The challenges introduced above also provide opportunities for the advanced research of graphene‐based moiré heterostructures. As the variety of 2D materials increases, an increasing number of moiré heterostructure compositions may be attempted, including, but not limited to, graphene‐based moiré heterostructures. A combination of other 2D materials apart from graphene may be utilized. In addition, the discovery of new moiré heterostructures is likely, which will have profound significance for the design of multi‐function devices and research on physical properties. For example, the supermoiré heterostructure truction.190 AdThe authors declare no conflict of interest.