Virtual reality (VR) has gained popularity in daily life, and VR food cues seem to elicit food cravings, similar to real food cues. However, little is known about the impact of VR food cues on actual food intake.In real life (RL), exposure to food cues in a situation in which the desire to eat food interferes with the completion of a food-related task reduces the subsequent food intake . In this study, we examine, on the one hand, whether the pre-exposure effect could be replicated in RL and, on the other hand, whether this effect could be extended to VR contexts.The study used a 2 (stimulus type: food vs nonfood) × 2 (mode: VR vs RL) between-subject design (n=175). Participants were randomly assigned to 1 of the 4 conditions.P=.02). In addition, among female participants, we found that exposure to both food cues  resulted in lower food intake than exposure to both nonfood cues (P=.05). In contrast, this effect was not observed among male participants (P=.34). Additionally, VR and RL cues generated similar emotional and behavioral responses .We found the main effect of mode on food intake, with a higher food intake after both VR conditions than after RL conditions  reduces food intake, indicating that a VR pre-exposure procedure may effectively be applied exclusively for women.ClinicalTrials.gov NCT05169996; https://clinicaltrials.gov/ct2/show/NCT05169996 It is teir eyes . Howevereir eyes . This mens et al  and has ns et al  and for ns et al . These dns et al . Given tRecently, technological advances, such as virtual reality (VR), have made it possible to run the pre-exposure procedure in a cost-efficient and flexible way. VR can simulate a virtual environment with tempting food stimuli by delivering multisensory cues , which lThe pre-exposure procedure is a 2-phase paradigm. In the original study that identified this procedure, participants in the experimental condition performed a consumer knowledge task in which they were asked to associate various wrappers of candies with the corresponding flavors . In contIn sum, the first aim of this paper is to replicate the pre-exposure effect with real food temptations among adults. We posit that exposure to real tempting food cues decreases subsequent intake of a similar tempting food as compared to exposure to nonfood cues. Moreover, the aim of the research is not only to replicate the pre-exposure effect with real foods but more importantly to better understand the potential of VR in the pre-exposure procedure. The next sections will focus on the extension of the pre-exposure effect to VR contexts.There is a large body of research on how consumers respond to food cues in VR. Prior research has shown that VR food cues can produce emotional  or behavioral  responses similar to those observed in real-life (RL) contexts ,11,18,19Overall, the prior literature suggests that consumers’ emotional and behavioral responses in food-related VR contexts are similar  to those in the RL ,22. In aIn sum, although there is a burgeoning body of research that focuses on how VR affects food cravings, marketers and researchers are struggling to fully understand the impact of VR on eating behaviors . It is important to note that our research focuses on the actual food intake (instead of food cravings) after interacting with food or nonfood cues in both VR and RL contexts. For the application in the VR context, we designed a task context where people could interact with the food in VR. To validate that this procedure could be used to trigger the pre-exposure effect, we tested it both in an RL and in a VR context. We assume that participants’ behavior in the VR context will be similar to their behavior after exposure to physical food temptations. In addition, prior research has shown that passive exposure to VR food cues induces high levels of food cravings as compared to VR nonfood cues . TherefoThis study used a 2 (stimulus type: food vs nonfood) × 2 (mode: VR vs RL) between-subject design. Participants were randomly assigned to 1 of the 4 conditions. A total of 218 participants (18-30 years old) were recruited with flyers and posters from a large Western European university. Participants received course credits or €7.50 for participation. This study was approved by the university ethical committee of the institution (file no. 2018-PC-9033) where the corresponding author was employed at the time of data collection. All participants provided written informed consent. In addition to the 4 conditions reported in this paper (n=175), an additional condition  was collected with the aim to investigate the effect of brands presented in VR on brand memory and purchase intention, and the results are reported elsewhere ,25.Participants were asked to refrain from eating 2 hours before the study. After entering the laboratory, participants were told that they were participating in 2 unrelated studies: a puzzle game and a taste test. First, they were asked to finish a tangram (puzzle game) with either food products  or nonfood products , either in VR or in RL (depending on their condition). Following that, they were asked to participate in a taste test of chocolate candies. Given the taste test, it was required that the participants were not allergic to peanuts (self-reported). Finally, they completed a questionnaire measuring game experiences  and emotional responses . We also measured the attractiveness of chocolate and the desire to eat chocolate for participants in the food cues condition (both VR and RL contexts). Participants also reported their demographic data  and data on height and weight. In addition, participants’ hunger levels and the completion time of the puzzle game were measured as covariates. After all measurements, the participants were thanked for their participation and debriefed on the fact that both studies were related. Note that the groups that were in the RL conditions also got an opportunity to play the VR game at the end of the procedure after all measurements (as the study was advertised as a study involving VR and the participants were told in the factsheet that they would engage in a VR game during participation).An immersive VR game was developed with a gameplay based on the pre-exposure effect. The game is played by wearing a head-mounted display VR  instrument and players can interact in the virtual environment with handheld controllers in the lab. The task in the game is to finish a tangram puzzle. Two versions of the game were developed, one in which the tangram pieces were tempting food products  and the other in which the tangram pieces were plain pieces see . PlayersIn the taste test, participants were presented with 2 bowls of chocolate, one with chocolate-covered peanuts from the brand M&M’s and the other with private label chocolate-covered peanuts. Participants were instructed to taste at least 1 of each bowl and were allowed to eat as much of the chocolate as needed to evaluate the products on several dimensions . Food intake was measured by weighing the bowls before and after the test. The participants were left alone in the lab for 5 minutes during the taste test to avoid socially desirable behavior. The distribution of food intake was skewed, so we transformed the food intake with a logarithmic format.We measured the perceived entertainment and difficulty of puzzle games as indicators of game experiences. Specifically, the perceived entertainment was measured with 4 items  on a 7-point scale . The perTo assess whether emotional responses induced in VR contexts were similar to those generated in RL contexts, we measured arousal and valence using the Self-Assessment Manikin (SAM) scale . The SAMr=0.75, P<.001).In the food cues condition, we also measured the appeal of food. Specifically, the attractiveness was measured with a single item  on a visual analog scale (VAS) ranging from 0  to 100 (“a whole lot”). Similarly, the desire to eat chocolate was measured with a single item  on a 7-point scale ranging from 1  to 7 (“a whole lot”). The 2 measures were correlated with each other (2 (SD 2.7). Data from 13 participants were excluded from analysis because of nonconforming to the study tasks , impossible values , reporting a low preference for chocolate , or spontaneous mention of not liking the peanut M&M’s (n=1). The final sample consisted of 162 adults  with a mean age of 22.4 years (SD 4.1) and a mean body mass index (BMI) of 21.9 kg/mF3,158=0.092, P=.97), gender , BMI , weight concerns , chocolate preference , hunger , and time since last intake . These results indicate that our randomization was successful.We conducted a randomization check to test whether the sample was distributed equally across conditions see . We compF1,158=2.234, P=.14, partial η2=0.014). A main effect of mode was found . Food intake (g) was higher in the VR condition  than in the RL condition . The interaction between stimulus type and mode was not significant . R2 of the complete model was 0.047 (adjusted R2=0.029); we also performed an analysis controlling for the hunger level, liking of chocolate candies, and time since the last intake as covariates, and the significant level of the main effects was not substantially different.ANOVA with stimulus type (food vs nonfood) and mode (VR vs RL) as independent variables and food intake  as the dependent variable was performed. No significant main effect of stimulus type was found . Food intake (g) was higher in the nonfood condition  compared to the food condition . A main effect of mode was found . Food intake (g) was higher in the VR condition  than in the RL condition . The interaction between stimulus type and mode was not significant . R2 of the complete model was 0.070 (adjusted R2=0.045).ANOVA with stimulus type (food vs nonfood) and mode (VR vs RL) as independent variables and food intake  as the dependent variable was performed. A significant main effect of stimulus type was found . No significant main effect of mode was found . The interaction between stimulus type and mode was not significant . R2 of the complete model was 0.038 (adjusted R2=–0.034).ANOVA with stimulus type (food vs nonfood) and mode (VR vs RL) as independent variables and food intake  as the dependent variable was performed. No significant main effect of stimulus type was found . No main effect of mode was found . The interaction between stimulus type and mode was not significant . R2 of the complete model was <0.001 (adjusted R2=0.019).To test whether the game experience produced by VR cues was similar to that produced by RL cues, ANOVA with stimulus type (food vs nonfood) and mode (VR vs RL) as independent variables and entertainment as the dependent variable was performed. No significant main effect of stimulus type was found . No main effect of mode was found . The interaction between stimulus type and mode was not significant . R2 of the complete model was 0.031 (adjusted R2=0.012).ANOVA with stimulus type (food vs nonfood) and mode (VR vs RL) as independent variables and difficulty as the dependent variable was performed. No significant main effect of stimulus type was found . No main effect of mode was found . The interaction between stimulus type and mode was not significant . R2 of the complete model was 0.012 (adjusted R2=–0.007).To test whether emotional responses produced by VR cues are similar to those produced by RL cues, ANOVA with stimulus type (food vs nonfood) and mode (VR vs RL) as independent variables and valence as the dependent variable was performed. No significant main effect of stimulus type was found . No main effect of mode was found . The interaction between stimulus type and mode was not significant . R2 of the complete model was 0.007 (adjusted R2=–0.012).ANOVA with stimulus type (food vs nonfood) and mode (VR vs RL) as independent variables and arousal as the dependent variable was performed. No significant main effect of stimulus type was found . R2 of the model was 0.014 (adjusted R2=0.002).To test whether food cravings produced by VR food cues are similar to those produced by real food, ANOVA with mode (VR vs RL) as the independent variable and chocolate attractiveness  as the dependent variable was performed. Note that we only used half of the data set for subsequent analyses because only half of the participants were exposed to food cues. No main effect of mode was found . R2 of the model was 0.033 (adjusted R2=0.020).ANOVA with mode (VR vs RL) as the independent variable and the desire to eat chocolate (answer to “How much did you feel like eating the chocolate?”) as the dependent variable was performed. No main effect of mode was found . The completion time was longer in the nonfood condition  compared to the food condition . A main effect of mode was found . The completion time (seconds) was longer in the RL condition  than in the VR condition . The interaction between stimulus type and mode was also significant . Simple contrasts revealed that when in RL mode, the completion time was longer in the nonfood condition  than in the food condition . However, in VR mode, there was no significant difference in the completion time between the 2 conditions . Additionally, simple contrasts revealed that when the stimulus type was nonfood, the completion time was longer in the RL condition  than in the VR condition . However, when the stimulus type was food, there was no significant difference in the completion time between the 2 conditions . R2 of the complete model was 0.120 (adjusted R2=0.104).In this study, we also measured the completion time of the puzzle game. To test whether participants spent a similar amount of time in completing the puzzle game between VR and RL contexts, ANOVA with stimulus type (food vs nonfood) and mode (VR vs RL) as independent variables and completion time as the dependent variable was performed. As shown in Due to the rising popularity of VR in our daily life, it is necessary to better understand how VR food cues affect consumers’ eating behavior . However, prior research has mainly focused on the impact of VR food cues on food cravings ,12,20,21Unexpectedly, we found that the main effect of mode (VR vs RL) on food intake is significant. Specifically, we found a higher food intake after both VR conditions (puzzle game in VR with either food or nonfood cues) than after RL conditions. A possible explanation could be that playing a game in VR is arousing and that arousal leads to increased food intake. There is ample evidence that arousal may lead to increased food intake . Howeverfemale=6.000 (SD 1.147) versus Mmale=5.364 (SD 1.382), with F1,160=8.792 and P=.003. Consequently, given that tempting chocolates may induce a behavioral conflict between the desire to eat and the completion of a food-related task among females, we observed the pre-exposure effect. In contrast, chocolates may not have been sufficiently tempting for males, therefore resulting in a lack of behavioral conflict and activation of control processes in males.We did not replicate the pre-exposure effect in the full sample. In addition, there was no interaction effect between stimulus type (food vs nonfood) and mode (VR vs RL) on food intake in the full sample. Prior studies have shown that pre-exposure effects are in some instances specific to males  or femalMoreover, we found that emotional and behavioral responses  induced by VR cues are similar to those generated by RL cues. This suggests that there were no additional confounders between the conditions. In addition, this study showed that exposure to VR food cues elicits similar food evaluations  compared to exposure to RL food cues. Given that the appeal of food (measured in this study) was similar to food cravings (measured in prior studies), this study does not provide evidence that VR food cues induce weaker food cravings compared to RL food cues ,22. In tAlthough this study provides useful insights into the impact of VR cues on food intake, 3 limitations should be considered. First, in this research, we found that manipulation affects the completion (exposure) time of puzzle games. Specifically, participants spent more time completing puzzle games in nonfood or RL conditions as compared to food or VR conditions. We tried to replicate the pre-exposure effect in RL contexts; however, the completion time was longer in the nonfood condition (around 5.5 minutes) than in the food condition (around 3.5 minutes). Prior research on the pre-exposure effect used a consumer knowledge task , a puzzlSecond, this research used the pre-exposure paradigm  to examine the effect of VR cues on food intake. Both tasks are more specific to laboratory contexts. Until now, we are not clear whether the pre-exposure procedure still works well outside laboratory contexts. Given the unlimited possibility of creating various eating environments with HMD-VR, future research could examine how VR affects food intake in different situations. Prior research on VR food cues focused on some daily environments, such as living rooms, kitchens, and restaurants. For instance, there was no significant difference in food intake between the restaurant scene and the blank scene in VR environments . HoweverThird, in this study, we exclusively used confectionery food products when manipulating pre-exposure  and when measuring food intake . Both products belong to the same food category, which warrants caution with generalizing our results across all food products. Concretely, individual differences in perceptions of how appealing the stimulus food was, as well as strong preferences in particular brands of confectionery food products, could have affected food intake (at least) on the individual level. To rule out any potential product-specific bias, future studies could consider incorporating different or various food categories to manipulate pre-exposure as well as to measure food intake.Our findings contribute to 2 streams of literature: the pre-exposure procedure and the responses to VR food cues. Although prior research on the pre-exposure procedure has studied how food cues versus nonfood cues affect the subsequent intake of tempting foods in RL contexts ,4,15, ouFurthermore, our research extends the VR food cues literature by examining the impact of VR on actual food intake, instead of food cravings, considering that actual food intake is critical to understanding whether VR food cues increase or decrease subsequent intake of tempting foods in more naturalistic settings. In addition, in line with prior research on the effects of VR food cues on eating behavior–related outcomes ,10, the Overall, in this study, we were unable to replicate the exposure effect in our complete sample. Subgroup analyses, however, showed that for women, exposure to food cues (either in VR or in RL) does reduce food intake, indicating that a VR pre-exposure procedure may effectively be applied exclusively for women. Moreover, we found that exposure to cues in VR (either food or nonfood) results in a higher overall food intake as compared to exposure to cues in a similar RL setting. Finally, we demonstrated that VR and RL cues elicit similar emotional responses .


The as-prepared fully exposed Pt3 cluster catalyst shows higher conversion (35.4%) and remarkable alkene selectivity (99.0%) for n-butane direct DDH reaction at 450 °C, compared to typical Pt NP and Pt SA catalysts supported on ND@G. Density functional theory calculation (DFT) reveal that the fully exposed Pt3 clusters possess favorable dehydrogenation activation barrier of n-butane and reasonable desorption barrier of butene in the DDH reaction.Metal nanoparticle (NP), cluster and isolated metal atom  exhibit different catalytic performance in heterogeneous catalysis originating from their distinct nanostructures. To maximize atom efficiency and boost activity for catalysis, the construction of structure–performance relationship provides an effective way at the atomic level. Here, we successfully fabricate fully exposed Pt 3 clusters and correlate dehydrogenation activity with average coordination number of Pt-Pt bond.Direct dehydrogenation has been a thematic research area resulting from the energy shortage and petroleum gas upgrading scenario. Here, the authors fabricate fully exposed Pt For a typical supported metal catalyst, many factors including the crystallographic surface, chemical composition, particle size, and metal–support interaction can affect catalytic performances2. Recently, it has been found that well-dispersed nanoparticles (NPs), clusters, and isolated metal atoms  exhibited surprisingly different catalytic performances from bulk materials with the development of the advanced characterization tools and well-controlled synthesis technology, leading to the establishment of the structure–performance relationship at the atomic level11.Heterogeneous catalysis plays an indispensable role in chemical production12, low adsorption energy of reactants/intermediate13 and maximal atom utilization15. Nevertheless, it is worth noting that clusters, though with inactive bulk components, were more active than SAs in some catalytic reactions. Anderson et al.16 deposited size-selected Aun+  on TiO2 support to study the relationship between Au size and CO oxidation activity. Owing to adverse CO-Au binding, Au or Au2 was inactive for CO oxidation. The activity was found in the order of Au7 > Au3 > Au4 > Au2 ≈ Au1. Corma et al.18 studied the size effect of different types of Pt species  supported on various oxides. In the low-temperature NO reduction reaction with CO, the surface of Pt clusters favored NO dissociation and CO oxidation. The moderate adsorption of CO on Pt clusters could suppress catalyst poisoning, leading to higher activity than that of Pt SAs. Szanyi et al.19 found that Ru clusters favored CH4 formation in contrast to Ru single atoms. Due to the limited ability to activate hydrogen, single Ru atoms can only allow CO formation but cannot further hydrogenate it to CH4. However, we find later that the modulation of the chemical state of metal species by strong metal–support interaction is more important for observed selectivity regulation  in CO2 hydrogenation reaction over Ir/CeO2 catalyst with different size of Ir species20. Nevertheless, the highly dispersed subnanometer-sized metal clusters (<1 nm) achieve maximum atomic exposure and utilization and possess various chemical coordination environments and chemical states that eventually affect the activity, selectivity, and stability of catalysts. It is the cluster with certain size, instead of single atoms, that was linked to high stability, selectivity, and activity in the heterogeneous catalysis, where the catalysts showed remarkable performance on structure-sensitive catalytic reactions22. But the small clusters always suffered from aggregating into metal NPs at high temperature, limiting their applications into high-temperature reactions26. Therefore, considering industrial application, designing thermodynamically stable metal cluster with low metal loading  still remains highly desired.In several previous works, SAs catalysts exhibit advantages such as unique reaction pathway28. The primary catalyst designated for DDH is a Pt-based catalyst30. The side reactions of DDH including coke deposition, hydrogenolysis, and cracking are usually structure-sensitive, which prefer to occur on Pt NPs with large average Pt–Pt coordination numbers (CN)31. An ideal solution to suppress side reactions and promote catalytic performance is to downsize Pt NPs and regulate CN of Pt to a moderate level. In general, the addition of promoter metals to Pt afforded bimetallic and alloying systems, which can improve both the dispersion and stability for Pt species. For instance, as to n-butane dehydrogenation, Pt particle sizes decreased with increasing Sn loading in the PtSn/θ-Al2O3 catalyst. Higher atomic efficiency and the formation of PtSn alloying phases were correlated with higher activity and n-C42− selectivity. But the conversion rate remained low at each active site in such a large size PtSn alloying system32. Considering maximize atomic utilization, Pt/Cu single atom alloy catalyst is proposed in propane dehydrogenation. Compared with Pt NPs, isolated Pt atoms dispersed on copper nanoparticles dramatically enhance the propylene selectivity and stability33. Several bimetallic cluster catalysts have also been reported, including small raft-like PtSn clusters34, PtSn/ND@G35, Pt/Sn-Beta catalysts36, PtSn cluster38, and PtZn clusters defined in zeolites40, which displayed high activity for DDH reaction with excellent durability. But it also remains major challenges to synthesize clusters with precisely controlled metal-metal coordination numbers, and fundamentally understand the structure effects  on dehydrogenation performance at atomic level.Direct dehydrogenation (DDH) for light olefins production has been a thematic research area resulting from the energy shortage and petroleum gas upgrading scenario3 clusters stabilized on the defective graphene through Pt–C bond, with the geometric partitioning by the atomically dispersed Sn promoter, which can precisely tune the CN of supported Pt clusters based our previous reported methods35. The obtained Pt3 clusters with 0.5 wt% Pt loading showed higher conversion for n-butane DDH than Pt NPs and Pt SAs supported on ND@G. At a relatively low temperature (450 °C), n-butane rate of Pt3 clusters has achieved 1.138 mol·gPt−1·h−1. Moreover, we systemically established the structure–performance relationship by correlating the DDH activity with the average CN of Pt–Pt bond on ND@G supported Pt NP, Pt cluster, and Pt SA catalysts. By density functional theory (DFT) calculations, we found that the Pt3 cluster catalyst’s unique structure facilitates the activation of C–H bond and the desorption of butene. Such a structure–performance relationship may provide an insight for rationally designing highly active heterogeneous DDH catalysts in atomic scale.In this paper, we fabricated fully exposed Pt3 cluster catalysts, a serial of PtSn/ND@G catalysts were prepared by the co-impregnation method, denoted as Pt0.8Sn/ND@G (Sn/Pt atomic ratio = 0.85), Pt1.7Sn/ND@G (Sn/Pt atomic ratio = 1.7), Pt3.4Sn/ND@G (Sn/Pt atomic ratio = 3.4), and Pt6.8Sn/ND@G (Sn/Pt atomic ratio = 6.8). The Pt and Sn precursors anchored on the ND@G support composed of a diamond core and a defect-rich graphene shell  was carried out. Due to the difference in Z-contrast, the supported Pt species can be easily distinguished from Sn atoms, as shown in Fig. 0.8Sn/ND@G  and Pt6.8Sn/ND@G (the dispersion of Pt was 5.6%). In other words, the excess Sn species did not further promote the Pt dispersion but covered up the Pt clusters, preventing Pt atoms from being exposed to adsorbed reactant molecules.Besides, from the XRD profiles , Pt foil, and PtO2 are shown in Fig. 0.8Sn/ND@G catalyst, it exhibited a distinct peak at 1.7 Å and a weak peak at 2.6 Å, which matched up with the first coordination shell of Pt−C/O and Pt–Pt, respectively, indicating that Pt NPs were located on ND@G support through Pt–C bonds. The average CN of Pt−C/O was 3.1, and the average CN of Pt−Pt was 3.2. Notably, for the Pt1.7Sn/ND@G, Pt3.4Sn/ND@G and Pt6.8Sn/ND@G samples, they all showed a strong signal of Pt−C/O and a relatively weak signal of Pt–Pt. For the Pt1.7Sn/ND@G catalyst, the average CN of Pt−Pt is ~2 (2.3), verifying the presence of Pt3 clusters. Due to the limitation of the characterization methods ), the coordination property of Pt atoms is statistically averaged. The realistic Pt clusters on current catalyst could have distribution in both atomicity and configuration42, but the majority of Pt clusters compose of around three Pt atoms. Moreover, all the Pt atoms in the Pt3 clusters (dispersion of Pt was 99.1%) are fully exposed. Significantly, both the features of high dispersion and fully exposure allow all the Pt atoms accessible for adsorbing reactant molecules. For the Pt3.4Sn/ND@G and Pt6.8Sn/ND@G catalyst, the CN of Pt–Pt is 2.0 and 2.1, respectively, similar to that of Pt1.7Sn/ND@G, suggesting that Pt atoms in Pt3.4Sn/ND@G and Pt6.8Sn/ND@G mostly existed in the form of Pt3 clusters. In contrast, for the Pt/ND@G catalyst, the average CN of Pt−Pt bond was 6, indicating the formation of large Pt NPs, agreeing well with the STEM results. The wavelet transformation (WT) of Pt L3-edge EXAFS oscillations visually displayed the structure of Pt species in both the k and R spaces  measurement was employed to provide detailed information of the structure and the local environment of Pt and Sn species. From the X-ray absorption near edge structure (XANES) spectroscopy, the intensity of the white line for as-prepared catalysts situated above that of Pt foil, indicating the existence of slightly positively charged Ptort Fig. . The EXAces Fig. . Figure 0.8Sn/ND@G, Pt1.7Sn/ND@G, Pt3.4Sn/ND@G, and Pt6.8Sn/ND@G to understand the role of Sn species on catalytic performance under the atmospheric condition and at 450 °C. The conversion of n-butane and the selectivity to C4 olefin over those catalysts are shown in Fig. Pt−1·h−1. The value of Kd  and the initial selectivity at 10 h were 0.0421 h−1 and 96.0%, respectively. In general, the deactivation of DDH reaction was attributed to the sintering of Pt NPs with large Pt–Pt CN, resulting in structure-sensitive side reactions and coke formation to block Pt active sites on the catalyst surface43. Notably, benefited from the mono-dispersed Sn, the catalytic performance of Pt0.8Sn/ND@G was dramatically enhanced. The butane conversion reached 25.9% and then dropped to 20.8% in 10 h test. The selectivity towards C4 olefin reached 98.9% at the initial stage. The value of Kd was 0.0313 h−1, showing that the lifetime was extended with decreasing CN of Pt–Pt. Significantly, the Pt1.7Sn/ND@G catalyst possessed excellent catalytic activity and remarkably high selectivity for n-butane DDH. Figure 4 olefin was as high as 99.0% at the initial stage, and the value for Kd was only 0.0223 h−1. When further adding Sn species, the conversion and n-butane rate dramatically decreased over the Pt3.4Sn/ND@G and Pt6.8Sn/ND@G catalysts as shown in Fig. 4 olefin selectivity over Pt3.4Sn/ND@G and Pt6.8Sn/ND@G were both close to that of Pt1.7Sn/ND@G. For Pt3.4Sn/ND@G and Pt6.8Sn/ND@G, the structure of atomically dispersed Pt3 was almost intact, but the excess Sn species covered up the Pt3 clusters, causing Pt dispersion decrease from 99.1% to 5.6%, as shown in Fig. 3 clusters can significantly reduce the conversion and n-butane rate. As shown in Fig. 0.8Sn/ND@G and Pt1.7Sn/ND@G. When Sn/Pt  = 1.7, the atomically dispersed Pt3 cluster was thought to be the optimum catalyst, as all the Pt atoms are full exposed for n-butane DDH. Moreover, with the increase of reaction time, the butane conversion and the selectivity for Pt1.7Sn/ND@G catalyst remained constant at 24% even after 50-h of reaction , and Pt1/ND@G (Pt SA). Firstly, aberration-corrected HAADF-STEM was employed to investigate the morphology of Pt1/ND@G. As shown in Supplementary Fig. 1/ND@G showed that no Pt crystal or Pt-oxide phase was observed , Pt1.7Sn/ND@G (Pt3 Cluster), and Pt1/ND@G (Pt SA), respectively. The fully exposed Pt3 clusters showed the best catalytic performance for n-butane DDH reaction than Pt/ND@G and Pt1/ND@G. Clearly, the n-butane DDH rate of Pt1.7Sn/ND@G (1.138 mol·gPt−1·h−1) was higher than those of Pt/ND@G (0.373 mol·gPt−1·h−1) and Pt1/ND@G (0.193 mol·gPt−1·h−1). Consistently, the initial selectivity towards butene on Pt1/ND@G was only 97.1%, followed by Pt1.7Sn/ND@G (96.6%) and Pt/ND@G (93.1%). Figure 31. But interestingly, the n-butane conversion rate did not increase proportionally with a decrease of the Pt–Pt CN in Fig. 1.7Sn/ND@G, but Pt1/ND@G.Figure 1.7Sn/ND@G, and Pt1/ND@G. In the DFT calculations, Pt (111) surface, Pt SA on single-lay graphene (Pt1-Gr), and a triangle Pt3 cluster doped into single-vacancy graphene (Pt3-Gr) were used to model Pt/ND@G, Pt1/ND@G, and Pt1.7Sn/ND@G, respectively. The dehydrogenation process follows four steps: (i) the adsorption of n-butane; (ii) the dehydrogenation of n-butane to surface adsorbed 2-C4H9 species (2-C4H9*); (iii) the surface adsorbed 2-C4H8 (2-C4H8*) is generated via the further dehydrogenation of 2-C4H9*; (iv) the desorption of 2-C4H8* to form the product 2-butene gas. Supplementary Tables 1-Gr, Pt3-Gr, and Pt (111). The Gibbs free energy profile of butane dehydrogenation to 2-butene on these three models is shown in Fig. 1-Gr), 1.19 eV (Pt3-Gr), and 2.00 eV (Pt (111)), respectively, suggesting that the Pt3-Gr is the most active for butane dehydrogenation. These data provide a rational interpretation for the high catalytic activity of Pt3-Gr and low activity of Pt1-Gr in our experimental observations. Deep hydrogenation  is known to be the origin of coke and hydrogenolysis44. The difference between the energy barriers of deep dehydrogenation (EDH) and the desorption (EDP) of 2-butene (ΔES = EDH − EDP) can be used to evaluate the selectivity of dehydrogenation from alkanes to alkenes44. The more positive of the value ΔES indicates the better selectivity of the catalyst. Supplementary Fig. S for Pt1-Gr (0.45 eV), Pt3-Gr (0.11 eV), Pt (111) (−0.04 eV), respectively. Due to insufficient metal active sites to the further dehydrogenation and weak adsorption of 2-butene, Pt1-Gr exhibits the best selectivity compared to Pt3-Gr and Pt (111). Based on the calculated results, Pt3-Gr is predicted to have high activity and selectivity for the butane dehydrogenation to butene, while Pt1-Gr is expected to have high selectivity and relatively low activity, which agrees well with the aforementioned experimental observations.To better understand the relationship between metal size and its catalytic performance, DFT calculations were conducted to unveil the difference in dehydrogenation among Pt/ND@G, Pt3 clusters where the atomically dispersed Sn atoms play the role of geometric partitioning. We constructed the structure–performance relationship between Pt NP, fully exposed Pt3 cluster, and Pt SA for n-butane DDH reaction. The fully exposed Pt3 clusters showed the highest n-butane conversion and remarkable alkene selectivity, compared to Pt NPs and Pt SAs, resulting from the facilitated activation of C–H bond and the desorption of butene. Such relationship between Pt CN and n-butane DDH activity provides a valuable insight in the structure effect on catalytic performance and thus a new avenue to design DDH catalysts with high activity, selectivity, and stability.By optimizing the loading amount of Sn promoter, we fabricated fully exposed Pt2PtCl6 ∙ 6H2O) and Tin (II) chloride dehydrate (SnCl2 ∙ 2H2O) as metal precursors were purchased from Sinopharm Co. Ltd.Nanodiamond (ND) powders with the average diameter of 30 nm were purchased from Beijing Grish Hitech Co., China. Analytical grade chloroplatinic acid (H−1) for 4 h under flowing Ar gas (80 mL·min−1). When it finished and cooled to room temperature, the final powder, ND@G, was collected for further use. A series of PtSn/ND@G catalysts were prepared by co-impregnation method using a fixed weight loading of Pt (0.5%) with varying weight loading of Sn: Pt0.8Sn/ND@G (Sn/Pt atomic ratio = 0.85), Pt1.7Sn/ND@G (Sn/Pt atomic ratio = 1.7), Pt3.4Sn/ND@G (Sn/Pt atomic ratio = 3.4), Pt6.8Sn/ND@G (Sn/Pt atomic ratio = 6.8). First, certain amount of H2PtCl6 (20 g/L) and SnCl2 ∙ 2H2O (6.0 g/L) were dissolved in 1 ml ethanol and generated a clear solution. Then, 100 mg ND@G powder was added and impregnated in the liquid solution. After that, the samples were dried in air at 80 °C for another 6 h. Finally, the solid sample were calcined in Ar (80 mL ⋅ min−1) at 500 °C for 4 h and subsequently reduced in H2 gas (80 mL ⋅ min−1) at 500 °C for 1 h. For reference, the Pt/ND@G (0.5 wt% Pt) was prepared with the same process without the addition of Sn. Pt1/ND@G (0.1 wt% Pt) was also prepared with the similar process without the addition of Sn and reduced by thermal treatment in H2 gas at 200 °C for 1 h.The nanodiamond@graphene (ND@G) hybrid carbon support was prepared by annealing fresh nanodiamond powders at 1100 °C (heating rate 5 °C·minλ = 1.54 Å). HAADF-STEM measurements were conducted with a JEOL JEM ARM 200CF aberration-corrected scanning transmission electron microscope at 200 kV accelerating voltage. XAFS measurements of the samples were carried out in Shanghai Synchroton Radiation Facility (SSRF). The H2-O2 titration measurements were performed on a Micromeritics AutoChem II 2920 equipped with a thermal conductive detector.The series of samples were characterized by X-ray diffraction (XRD) on a D/MAX-2500 PC X-ray diffractometer with monochromated Cu K radiation  of 18,000 mL∙gcat−1 ∙ h−1 on the basis of the whole feed gas .The catalytic test for the DDH reaction of n-butane was tested using a fixed-bed stainless-steel micro-reactor with a quartz lining under atmosphere pressure at 450 °C, equipped with an online gas chromatography instrument (Agilent 7890 with an FID and a TCD detector). First, 50 mg of sample was loaded into the stainless-steel reactor. The reaction was carried out in a feed gas with a composition of 2% H4 olefin  were calculated by the following formula:The rate and conversion of n-butane and the selectivity of total Ci is initial conversion after reaction 30 min; Cf is final conversion value; t represents the reaction time (h); and kd is the deactivation rate constant (h−1) that is used to evaluate the catalyst stability .The catalyst stability was described by a first-order deactivation model:46 was used to perform spin-polarized DFT computations with the projector augmented wave (PAW) method48. The generalized gradient approximation in the form of the Perdew-Burke-Ernzerhof functional (PBE)49 was chosen for electron exchange and correlation. An energy cutoff of 400 eV was employed for the plane wave expansion. The ground-state structure of bulk and surfaces were obtained by minimizing forces with the conjugate-gradient algorithm until the force on each ion is below 0.02 eV/Å, and the convergence criteria for electronic self-consistent interaction is 10−5.The Vienna ab initio simulation package (VASP) code3 cluster and Pt single atom embedded into a monovacancy at 5 × 5 supercell of graphene was adopted to simulate the active site of butane dehydrogenation (Pt3-Gr) through comparative investigation between potential Pt cluster models and EXAFS data. The vacuum layer was set to 20 Å to avoid interaction from adjacent cells. The Monkhorst–Pack k-point set to 3 × 3 × 1 in the reciprocal lattice, and the electronic occupancies were determined according to the Gaussian smearing method with σ = 0.1 eV. Spin-polarized calculations were performed. For Pt (111) surface, a four-layer slab with a (3 × 3) supercell  was employed. The successive slabs were separated by a vacuum region as thick as 20 Å to eliminate periodic interactions. The Brillouin zone is sampled with a 3 × 3 × 1 k-points mesh by the Monkhorst–Pack algorithm. The electronic occupancies were determined according to the Methfessel-Paxton scheme with σ = 0.2 eV. The bottom two layers of the slab were kept fixed to their crystal lattice positions. Spin-polarization is not considered in Pt (111) calculation. We have calculated zero-point energies (ZPE) of reaction species and transition states.A model with Pt3-Gr, Pt1-Gr and Pt (111) surface were obtained by the standard minimization of density functional theory (DFT). These configurations were used as the initial states, from which the constrained optimization method as described by Plessow. P. N50. was used to search the transition states (TS). The TS optimization convergence was regarded to be achieved when the force on each atom was less than 0.05 eV/Å. All transition states have been verified to include only one imaginary harmonic frequency corresponding to the transition vector of the reaction. Furthermore, small distortions along the transition vector followed by optimization toward the minima verified the connectivity of the transition states. The entropy contributions of butane, 2-butene and hydrogen gas were included in the free energy calculations. The most important contributions arise from the translational entropy51, which can be calculated using the following equation:2 gas gained 1.34 eV and 1.02 eV. It should be noted that the partial calculation work on the Pt3-Gr model is based on the theoretical part of our previous work35, and has been further improved in the Gibbs free energy calculations according to the main contribution of translational entropy.The most stable configurations of the reactant and intermediates on PtSupplementary InformationPeer Review File


Volumes of produced hydrogen were up to 25 and 6 times larger than those obtained with the corresponding free and cucurbit[7]uril-bound platinum monomer, respectively, at equal Pt concentration. The thermodynamics of the proton-coupled electron transfer from the Pt( The cucurbit[8]uril macrocycle can secure a platinum terpyridyl complex into a particularly reactive dimer that catalyzes the photoreduction of water. Sakai showed that Platinum(ii) terpyridyl (tpy) chloride 1a can be used both as a photosensitizer and H2-evolving catalyst in the presence of ethylenediaminetetraacetic acid (EDTA) as the sacrificial electron donor.3 A turnover number of approximately 3  was measured after 7 h in the presence of 0.4 mM of Pt complex 1a in a 2-(N-morpholino)ethanesulfonate (MES) buffer at pH 5.The design of artificial photosynthetic systems that split water into molecular hydrogen and oxygen remains a major challenge of our times.z2–dz2 orbital overlap of the Pt centers,15–17 Sakai questioned whether sensitization is triggered by complex 1a as a monomer or dimer. A dimerization constant of 4 (±2) × 103 M−1 and the quadratic dependence of the initial rate of H2 production as a function of the concentration of complex 1a (below 0.4 mM) indicate that either (a) photosensitization is mostly achieved by the 1a2 dimer – via a proton-coupled electron transfer (PCET) to the corresponding Pt(ii)–Pt(iii)–H hydride ruthenium(ii) cation as photosensitizer and methylviologen as electron relay. Furthermore, Yamashita and coworkers showed that grafting complex 1a onto solid supports  improves its catalytic activity by packing the complexes into arrangements with short Pt–Pt distances. This led us to consider the cucurbit[8]uril (CB[8])-secured Pt tpy dimers prepared recently in our group as a possible new family of single component catalysts for water reduction.23–26 In the past few years, we have shown that Pt tpy complexes substituted at the 4′-position with CB[8]-binding aryl units form 2 : 1 head-to-head “stacked” assemblies, with both Pt tpy units sitting on top of each other at the same CB[8] portal, i.e. with two positively charged guests interacting with the same CB[8] portal while leaving the opposite one void of any host/guest interaction , a weakly bonding pσ LUMO and a strongly anti-bonding pσ*. The stabilization of the dσ* HOMO confers a net energy gain to the interaction.27,28Sakai also showed that amidate-bridged Pt dimers . Hydrogen nuclei H7, H8 and H9 located at the CB[8]-binding tolyl unit experience a typical upfield shift upon encapsulation , and the Caryl–Cpyridyl torsional angles ϕ1 and ϕ2 between the CB[8]-binding tolyl group and the tpy scaffolds. In one assembly, both set of angles rotate in the same direction , and in the other, the directions are opposite  → π*(tpy)] transitions (the π*(tpy) orbital being better described as a 6pz(Pt)/π*(tpy) hybrid). Absorption bands above 350 nm are broad with lower extinction coefficients; they correspond to 1[5d(Pt) → π*(tpy)] metal-to-ligand charge transfers (1MLCT).The X-ray crystal structure of assembly CB[8]·1bcell see . This arλ = 447 ± 10 nm; 250 mW/LED). Aliquots were removed from the headspace and analyzed by gas chromatography as a function of time  in the presence of EDTA as sacrificial electron donor (30 mM). Solutions  were irradiated with 10 royal blue LEDs . CB[7] encapsulation of the tolyl tpy substituent does not significantly enhance performance, with up to 0.20 mL H2/10 mL solution at 1.0 mM Pt. Increasing the catalyst load above 0.50 mM and 1.0 mM is detrimental to H2 production, in the case of complexes 1b and CB[7]·1b, respectively . To the contrary, H2 production is increased by 25- and 6-fold when the CB[8]-secured Pt dimer is used as catalyst, compared to complexes 1b and CB[7]·1b . A pronounced increase in hydrogen production is observed as the catalytic load increases  formation using X-ray absorption fine-structure spectroscopy (XFAS),44 after irradiation of complex 1a (4.0 mM) and EDTA (30 mM) in a sodium acetate buffer at pH 5.2 solution was also monitored by electrospray ionization mass spectrometry, with 1.5 mM EDTA as sacrificial electron donor in water. Before irradiation, assembly CB[8]·1b2, its binary complex CB[8]·1b fragment, its free guest fragment, and an EDTA bridged Pt(tpy) dimer were detected  hydride cation  and the Pt concentration might have been detected when complex CB[8]·1b2 is used as the photocatalyst . However, the more soluble Pt thiolate 1c obtained after exchange of the chloride ligand with l-cysteine afforded a dimerization constant KPt–Pt of 4.0 (±0.4) × 104 by ITC in water, in very good agreement with the 7-fold lower constant measured for complex 1b in the high ionic strength buffer environment. A ternary binding constant β for complex 1c towards CB[8] of 1.9 (±0.6) × 1013 M−2 (see equilibrium 1) was extracted. In other terms, dimer 1c2 (and most likely dimer 1b2) can be considered as a standalone guest forming a very tight 1 : 1 complex with CB[8], with a binding affinity K′ of 5 (±2) × 108 M−1, obtained from 26 on a parent system.A linear correlation between the initial rate of Hlyst see . This re low see . As ment−1, respectively, in excellent agreement with the typical strength of Pt–Pt interactions.45 They also indicate that approximately 52, 66, 74 and 81% of Pt complex 1b is already present as a dimer at concentrations of 0.2, 0.5, 1.0 and 2.0 mM, respectively, even in the absence of CB[8], in the MES/EDTA buffer. While a simple dimerization process is sufficient to fit enthalpograms and changes in UV-Vis absorption, further aggregation into trimers or larger oligomers cannot be ruled out even if, in our case, considering those processes leads to over-parametrization.The dimerization constants of complexes 1b and 1c return free energy terms of −5.1 (±0.1) and −6.3 (±0.1) kcal moliii)–H hydride formation from the corresponding Pt(ii) complex  to calculate the free energy of Pt.11 Here, we can report that optimization in the gas phase with Grimme's newly developed B97-3c functional50 and def2-mTZVP basis sets51,52 returns accurate Pt–Pt distances and geometries highly similar to those measured by X-ray crystallography. The two CB[8]·1b2 arrangements  and 3.35 Å (vs. 3.44 Å), respectively. Cl–Pt–Pt–Cl dihedral angles are +3° and −21°, respectively, in perfect agreement with the X-ray crystal structure. Grimme also showed that for a set of reactions involving transition metals, the B97-3c functional not only returns realistic geometries, but also more accurate free energies compared to the B3LYP functional, even when the latter is supplemented with a dispersive term.50 The enthalpic and entropic contributions at 25 °C, as well as the free energies of solvation, were calculated using the tight-binding semi-empirical method GFN2-xTB currently developed by Grimme and coworkers53–55 , thereby indicating an even competition between the Coulombic repulsion of the positively charged Pt centres and the dz2–dz2 orbital overlap. This is also consistent with the presence of both arrangements in the unit cell of the X-ray crystal structure.Sakai notes that Pt–Pt distances obtained by DFT optimization (B3LYP/LANL2DZ)ents see  were reo2 were optimized at the same level of theory. The Cl–Pt–Pt–Cl dihedral angle in the most stable conformation of dimer 1b2 is 124°, and the Pt–Pt distance 4.99 Å –H hydrides at the same level of theory. As noted by Sakai, the Pt–Pt bond is reinforced compared to Pt(ii)–Pt(ii) interactions, and can be seen as a three-center two-electon Pt(ii)–Pt(iii)–H system11,56–58 with a Pt–Pt bond order of 0.5 (further oxidation to a d7–d7 Pt(iii)–Pt(iii) system would afford a σ bond between both metals, as the dz2–dz2 anti-bonding orbital would be empty). A unique CB[8]·1b2–H assembly is obtained with a pronounced shortening of the Pt–Pt bond  complexes into mixed-valence Pt(ii)2Pt(iii)2 complexes.59 The Pt–Pt axis also crosses the tpy planes almost perpendicularly -dz2(Pt)-s(H) hybrid  was also obtained (see ESIWe then optimized the corresponding open-shell Pt(brid see . A simild see ESI section.E) and free energies (ΔG) of the PCET processes . (2) CB[n] encapsulation does not provide any electrostatic contribution to the PCET process, as it is separated from the Pt centers by the tpy ligands . (3) Aggregation of free Pt complex 1b must severely hamper the catalytic process, as calculations indicate a more favorable PCET process for dimer 1b2 compared to complex CB[7]·1b , whereas hydrogen production is even poorer. (4) Most importantly, in addition to efficiently deaggregating Pt complex 1b (and likely preventing the formation of higher order oligomers), CB[8] secures the Pt dimer into a conformation that facilitates the PCET process. If dimerization of Pt complex 1b were quantitative in the presence and absence of CB[8], a 2.2 kcal mol−1 gain for the PCET process would be obtained upon addition of the macrocycle . The energy gain upon addition of CB[8] therefore ranges from 1.8 to 2.1 kcal mol−1 depending on Pt concentration. Also, removing CB[8] from complexes CB[8]·1b2 and CB[8]·1b2–H and carrying out single point energy calculations returns an electronic contribution ΔE of −31.4 kcal mol−1 for the PCET process, a 4.6 kcal mol−1 improvement compared to dimer 1b2 in its most stable conformation in the absence of CB[8] . In addition to being computed using adequate functionals and semi-empirical methods, we note that the quality of these calculated energy gains must be further enhanced by error compensation, as they represent relative stabilities of very similar assemblies. One can thus conclude that CB[8] encapsulation destabilizes dimer 1b2 by at least 1.8 kcal mol−1, enhances its reactivity, and promotes hydrogen production.The following observations can be made from the electronic contributions (Δsses see : (1) the60–62 we showed here, as a proof of concept with arguably modest TONs, that a macrocycle like CB[8] can be used as a tool to enhance the catalytic activity of a well-established family of multifunctional photocatalysts, namely Pt complexes. CB[8] effectively secures a pair of Pt complexes 1b on top of one another into reactive dimer CB[8]·1b2, which upon irradiation yields volumes of hydrogen up to 25 and 6 times larger than those obtained with the corresponding free monomer 1b and the CB[7]-bound control CB[7]·1b, respectively. A combination of semi-empirical and DFT calculations suggest that the kinetics and activity of the photocatalysts are governed by the thermodynamics of the PCET reaction from the Pt(ii) complexes to the corresponding Pt(iii)–H hydride intermediates. CB[8]-promoted dimerization not only renders the process more exergonic , as the PCET process is more favourable starting from a Pt(ii) dimer compared to a monomer, but also by forcing the dimer into a more reactive conformation for Pt(ii)–Pt(iii)–H hydride formation .While noble metal-free catalysts and chromophores can promote water reduction efficiently,All analytical data is provided in the ESI.†2. RR, SS, HB and MN conducted all other experiments. EM, RR, SS, HB and MN wrote the manuscript.EM conceived the project, and mentored RR, MN and HB; TAW mentored SS; TAW and SS designed the photolysis experiments. NK determined the single-crystal X-ray diffraction structure of assembly CB[8]·1bThere are no conflicts to declare.SC-012-D1SC03743A-s001SC-012-D1SC03743A-s002


The catalysts demonstrated excellent durability compared to a commercial Pt/C in load cycling, experiencing less than 50% changes in the mass-specific activity (MA) and surface area-specific activity (SA). In stop-start durability cycling, the new materials demonstrated high stability with more than 50% retention of electrochemical active surface areas (ECSAs). The results can be rationalised by the high BET surface areas coupled with an array of meso and micropores that led to Pt confinement. Further, pair distribution function (PDF) analysis of the catalysts confirmed that the nitrogen and oxygen functional groups, as well as the shell curvature/roughness provided defects and nucleation sites for the deposition of the small Pt nanoparticles. The balance between graphitic and diamond-like carbon was critical for the electronic conductivity and to provide strong Pt-support anchoring.The durability and long-term applicability of catalysts are critical parameters for the commercialization and adoption of fuel cells. Even though a few studies have been conducted on hollow carbon spheres (HCSs) as supports for Pt in oxygen reduction reactions (ORR) catalysis, in-depth durability studies have not been conducted thus far. In this study, Pt/HCSs and Pt/nitrogen-doped HCSs (Pt/NHCSs) were prepared using a reflux deposition technique. Small Pt particles were formed with deposition on the outside of the shell and inside the pores of the shell. The new catalysts demonstrated high activity (>380 μA cm The global dependence on fossil fuels for everyday energy needs is detrimental to the long-term sustainability of the earth. Over the years, scientists have shown that the combustion of fossil fuels for energy is the driver of rising global temperatures, recurring droughts and other adverse weather and climatic conditions . TherefoThe use of hydrogen fuel cells, commonly referred to as proton exchange membrane fuel cells (PEMFCs), could provide one solution to environmental and energy problems. These PEMFCs use platinum or its composites as the cathodes and anodes for the generation of electric currents usable in power machinery and equipment. The critical hydrogen oxidation reaction  or the oxygen reduction reaction  takes place on the Pt . Current2 and Pt is known to dissolve and redeposit on larger clusters facilitating the debilitating processes of dissolution and agglomeration (2 g−1), large pore volume (2.8 cm3 g−1) and mesoporous structure and they attributed the distribution and dispersion of small-sized Pt particles to these textual properties. In electrocatalytic reactions, they observed that the mass current density on Pt/HCS electrocatalyst was 1.7 times as high as that of commercial Pt/C in ORR. The stability of the electrocatalysts was attributed to the mesopores that provided a physical interaction force between the Pt and the HCSs. The researchers acknowledged both the superiority of Pt nanoparticles in electrocatalysis and the role of the mesoporous hollow carbon spheres. Also in other studies  of other supports like metal oxides. In fuel cells, degradation occurs during load cycling or during the stop-start events where cell potentials can surpass 1.5 V vs. RHE. Above these potentials, carbon is electrochemically oxidized to COmeration . These dmeration . Though meration . Even thmeration . Separatmeration . Yan and studies , the mes studies .Therefore, herein we report on the electrochemical activity and load cycling and stop-start durability of Pt nanoparticles supported on HCSs and NHCSs (ca. 40 wt.% loading) and compare the data to a commercial benchmark Pt/C catalyst . The worPair distribution functional analysis (combined with other techniques) provided key information on the Pt-C and Pt-NC interactions and allowed for explanation of the data in terms of surface interactions.2, 97%], tetraethyl orthosilicate , resorcinol, formaldehyde (37%), Nafion perfluorinated resin solution  and ethylene glycol were all purchased from Sigma-Aldrich and used without further purification. Nochromix crystals (Gordax laboratories), ammonia solution , absolute ethanol , perchloric acid , ultrapure water , alumina polish , argon gas , oxygen gas , nitrogen gas , were obtained and used without further purification.Hydrofluoric acid (48%), cetyltrimethylammonium bromide (CTAB), ethylene glycol, absolute ethanol, melamine, methanol (99%), sulfuric acid (98%), platinum acetylacetonate [Pt (acac)The method described by Stober and colleagues was used, with minor changes, to prepare spherical silica templates . In the 2) template. In the procedure, the silica powder (1.5 g) was dispersed by sonication in a solution of absolute ethanol (105 ml) and deionized water (25 ml). The surfactant and porogen, CTAB (2 g), was added to a premixed solution of 37% formaldehyde solution (0.3 ml) and resorcinol (0.3 g) and 25% NH4OH solution (3 ml). The procedure proceeded with magnetic stirring for 24 h leading to the formation of SiO2@RF as the solution turned deep brown with vigorous stirring. After 24 h the products were filtered and washed with 500 ml of deionized water, followed by drying in an oven overnight at 100°C  was deposited on the silica (SiOat 100°C .2@RF) was transformed into a carbonaceous material using a tubular horizontal furnace saturated with argon at 900°C. Typically, the SiO2@RF (50 mg) was loaded into a quartz boat and placed in the centre of the furnace, under Ar flowing at 50 ml min−1. The furnace was ramped up to 900°C at a heating rate of 10°C min−1 and kept isothermal for 2 h. The quartz boat was cooled using a fast flow of compressed air for 30 min. The black soot (SiO2@C) was etched using a 10% HF solution in water (100 ml) for 24 h to remove the SiO2 template. To prevent the room temperature evaporation of the HF solution, the etching was conducted in a sealed Teflon container placed in a fume hood. The solution was vacuum filtered, washed with copious amounts of DI water and dried in an oven at 100°C overnight. The formed HCSs were annealed in a tubular horizontal furnace at 900°C for 2 h at a heating rate of 10°C min−1 under an argon flow rate of 50 ml min−1. The formed HCSs (600 mg) gave a yield of 88% based on the starting resorcinol and formaldehyde used.The dried brown product  followed by sonication for 30 min. The products were dried in an oven at 70°C for 2 h. The SiO2@RF-melamine was transformed to SiO2@NHCSs using the same procedure used for the SiO2@HCSs, after etching with HF to give NHCSs (The NHCSs were prepared from SiOve NHCSs .2 (27 mg) in a solution of absolute ethanol (100 ml), deionized water (10 ml) and ethylene glycol (10 ml) and the mixture sonicated for 30 min to allow for thorough mixing. The composite, placed in a round bottom flask (attached to a reflux condenser), was then placed in an oil bath heater. The bath was heated to 200°C at a slow heating rate of 2.5°C min−1 and kept isothermal for 2 h while the reaction continued under reflux. The reactor was allowed to cool naturally to room temperature, and the products were filtered under vacuum and washed twice with 300 ml deionized water followed by drying at 100°C  and Pt (acac)at 100°C .2 as the purge gas (20 ml min−1) and air for combustion (10 ml min−1) and a heating rate of 10°C min−1. Nitrogen adsorption/desorption was measured using a Micromeritics Tristar 3000 surface area and porosity analyser set at −195°C, with sample degassing conducted at 150°C overnight. Raman spectroscopy measurements were performed on a Horiba Jobin-Yvon Raman spectrometer with a laser wavelength of  ca. 10 mg of each catalyst in 1 ml ethanol for 5 min. About 3 drops of the material rich ink were deposited onto a lacey carbon copper grid, and analysis by TEM was done after drying the samples in air. Particle size distributions of the Pt particles, HCSs and NHCSs, were obtained by measuring at least 100 particles using ImageJ. The powder X-ray diffraction measurements were carried out on a Bruker D2 phaser diffractometer with a Cu Kα radiation source operating at 40 kV to determine the crystalline phases present in the catalyst with 2ϴ between 10° and 90°. Indexing the compounds detected by the PXRD technique was achieved using the EVA software. Particle sizes of platinum particles were calculated using the EVA software embedded Scherrer equation Thermal stability and metal loading of the catalysts was performed with a Perkin-Elmer STA6000 (TGA) analyser using N GSAS-II . The Qma4 purged with nitrogen for cyclic voltammetry (CV) or oxygen for the oxygen reduction reaction (ORR) experiments. The counter electrode was a high surface area Pt wire and the reference electrode was Ag/AgCl (3.0 M KCl). All Ag/AgCl potentials were converted to RHE by calibrating the potential between the reference electrode and an in-situ RHE prepared by saturating a clean Pt wire immersed 0.1 M HClO4 with hydrogen gas. Arbitrarily, no iR drop correction was conducted. For Pt and support durability studies, the high surface area Pt wire was replaced with a high surface area gold counter electrode. A catalyst thin film coated glassy carbon (GCE) electrode with a working area of 0.196 cm2 was used as the working electrode (WE). The catalyst inks were prepared by dispersing about 5 mg of the catalyst in a solution of ultrapure water , isopropyl alcohol  and Nafion perfluorinated resin solution  followed by a low-temperature 30 min sonication. The electrochemical cell, electrolyte volumetric flasks, purge tubes and reference electrode bridge tubes were all thoroughly cleaned with a solution of Nochromix and concentrated sulfuric acid followed by multiple rinses in Merck-millipore ultra pure water. A Biologic SP300/VMP300 potentiostat coupled to a Gamry RDE (rotating disk electrode) 710 Rotator was used for CV and RDE measurements.The electrochemical experiments were performed in a three-electrode cell at room temperature (approx. 25°C) in a solution of 0.1 M HClO−1 until a reproducible CV was obtained. The scan rate was then reduced to 50 mVs−1 and the third cycle was used for the calculation of the electrochemical active surface area (ECSA) assuming a monolayer charge associated with hydrogen adsorption of 210 µCcm−2. The area under the CV curve, representing the charge associated with the underpotential deposition of hydrogen (QDES), was integrated and used for the calculation of ECSA according to the equation:The potential of the WE was cycled between 0.0 and 1.2 V vs. RHE for 100 cycles at 100 mVsPt is the loaded amount of Pt particles on the 0.196 cm2 surface area of the working electrode. Oxygen reduction reaction (ORR) I (current)-V (voltage) polarization curves were obtained at 1,600 rpm on the electro-catalyst coated working electrode. The WE was cycled at 10 mV s-1 between 0.0–1.2 V vs. RHE in the cathodic direction. To correct for non-ORR background current, the LSV obtained in the nitrogen saturated electrolyte without rotation was subtracted from that obtained from the oxygen saturated electrolyte. The kinetic ORR currents (Ik) were extracted from the measured ORR currents (I) and the limiting currents (Ilim) determined at 0.4 V vs. RHE using the Koutecky-Levich equation.The LFinally, kinetic currents were normalised with the ECSA and the initial Pt mass loading to obtain the surface area-specific activity (SA), −1 to clean the catalysts of any impurities and contaminants and to produce a reproducible CV. Load cycling for catalyst durability measurements was carried out in a 0.1 M HClO4 solution at 25°C, in a nitrogen saturated electrolyte. The WE was cycled at 50 mV s−1 between 0.6–1.0 V vs. RHE. Load cycling was carried out in units of 10, 100, and 1,000 cycles until when the 6,000th cycle was reached after 27 h of continuous cycling. As Pt durability was under investigation, in all durability experiments, the Pt counter electrode was replaced with a gold counter electrode of high surface area (Durability load cycling was carried out after the measurement of the beginning of life (BOL) CV and ORR activity. Initially, the WE was cycled between 0.0–1.2 V vs. RHE at 100 mV sace area .−1 in an N2 saturated 0.1 M HClO4 electrolyte at 25°C. Cycling was carried out for a total of 6,000 cycles with ECSA CVs sampled after 10, 100 and 1,000 cycles until the 6,000th cycle was reached after 27 h of continuous cycling and argon saturation (Start-stop durability cycling was carried out after obtaining the beginning of life (BOL) ECSAs of the three catalysts. The WE electrode was cycled between 1.0–1.6 V vs. RHE at a scan rate of 50 mV sturation .2 hybridized carbons while the D band is attributed to the Raman vibration of sp3 hybridized carbons. The extent of graphitization was measured by the ratio of the D and the G band areas (ID/IG ratio). As expected, the HCSs with an ID/IG ratio of 0.98 were more graphitic when compared to the NHCSs, with an ID/IG ratio of 1.22. The nitrogen groups in the NHCSs introduced carbon vacancies in the structure of the NHCSs resulting in defects from displacement of carbon atoms by the nitrogen , amorphous diamond like carbon with sp3 hybridization, C–C (284.6 eV), C=N/C-O (285.8 eV), C–N/C=O (287.6 eV) and finally O–C=O (289.9 eV). The C=N and C-N bonds indicate the successful incorporation of the nitrogen functionalities into the carbon matrix of the NHCSs (7/2 (71.1 eV) and Pt4f5/2 (74.9 eV) and the +2 oxidation state of the Pt, Pt4f7/2 (72.1 eV) and Pt4f5/2 (76.2 eV), respectively,  . The Pt 2 bonding. The second peak (B) at 2.44 Å represents the distance between the three atoms coordinating a central carbon or the shortest diagonal in the hexagon. The third peak (C) at 2.86 Å, which is twice the first C-C distance, is the second, long diagonal in the hexagon. As can be seen from the simulation of graphite C-C bond distances in To further explore the effect of nitrogen on the HCSs structure, total scattering data were obtained and are plotted in 3 bonds originating from a R-3m rhombohedral diamond-like structures, albeit in lesser amounts relative to the graphite/ene phase  is not exactly half that of the second coordination sphere (B) . The NHC3 respectively which is just below the atomic density of graphite at 0.11 atoms/A3  from the scatterer is noted along the graphene sheet. This is likely due to the curvature of the sheets to form spheres, and the distribution of varying degrees of curvature in the sample, rather than from termination of sheet fragments. The effective atomic density of the scattering volume can be estimated from the slope of the measured G(r). For the HCSs and NHCSs samples the atomic density is 0.095 and 0.105 atoms/Aatoms/A3 . No inteatoms/A3 . All peaatoms/A3 .Atomic correlations are more significantly damped beyond 13 Å for HCS than NHCS. This is the range corresponding to the lateral coherence of the structures and also where stacking differences are important. This behaviour of G(r) indicates that short-range two-dimensional atomic order is similar to graphite but stacking along the c-axis is strongly disordered . HoweverThe effect of the addition of Pt to the HCSs and N/HCSs was also evaluated from total scattering data. The PDFs of HCSs and Pt/HCSs are shown in Fitting of the PDFs revealed mean Pt particle sizes of 2.6 and 2.4 nm for the Pt/HCSs and Pt/NHCSs, respectively. It is important to contrast the Pt particle sizes determined from XRD, TEM and PDF measurements. Considering XRD, Bragg diffraction has limitations in accurately determining particle sizes below 5 nm while the resolution and magnification of the TEM images likely result in an underrepresentation of very small particles smaller than 2.5 nm. PDF is highly sensitive to small particles as both Bragg and diffuse scattering are detected resulting in a more accurate particle size determination. The interaction of the Pt particles with the carbon surface has been shown to result in a local rearrangement of carbon atoms, with the stronger the adsorption energy, the larger the C–C bond elongation . As seenvia DFT calculations, this adsorption energy is proportional to the Pt particle sizes and has been shown to have profound effects on the Pt cluster properties  and kinetic current than the Pt/HCSs. The least active was the commercial benchmark Pt/C catalyst. The ORR onset, ECSAs, kinetic current and E1/2 data are summarized in −1 compared to 96 ± 6.5 mVdec−1 (Pt/HCSs) and 102 ± mVdec−1 , thereby confirming that ORR kinetics are more favourable on the nitrogen-doped catalyst, showing superiority to the commercial benchmark Pt/C  and ORR activity. The materials demonstrated a standard Pt/C cyclic voltammogram , with tyark Pt/C .−1, the Pt/HCSs a value of 387 ± 8 A g−1, both of which are ca. 10% larger than the commercial Pt/C (350 ± 10 A g−1) catalyst (−2) > Pt/HCSs (246 ± 17 µA cm−2) >Pt/C (203 ± 7 µA cm−2).The area-specific activities (SA) of the catalysts were obtained from the normalization of the kinetic current with the ECSAs of the catalysts. The Pt/NHCSs had a SA of 391 ± 16 A gcatalyst . The kincatalyst . The obsThe variation of catalysts activity was attributed to the physicochemical properties of the supports and N doping which affected the electronic properties of the catalysts. The interaction of the Pt and the N groups altered the electronic properties of the Pt-support resulting in better activity and a better Pt-support interaction. From the Pt surface, electron density is transferred to the π-conjugated system on the surface of the nitrogen groups due to differences in electronegativity creating a sea of electron density between the Pt particles and the N-functionalized surface. The same is less true on a pristine carbon surface. Here charge transfer occurs but the higher electronegativity of oxygen terminal functional groups means more of the electron density from the Pt is transferred to the oxygen functional groups. Thus, less of the charge is transferred to the carbon surface. As a result, the sea of charge on the pristine support is smaller than that on the N doped surface. Thus, electron flow is much easier on the N-doped surface than on the pristine surface, resulting in better activity in the former .2g−1) and Pt/NHCSs (309 m2g−1) and an array of micro and mesopores promotes better mass transport of oxygen to the Pt active sites compared to the less porous Pt/C benchmark catalyst with a surface area <200 m2g−1. The larger pores in the Pt/HCSs  and Pt/NHCSs  facilitates better “in-pore” confinement of the Pt inside the pores and thereby promotes a better Pt-support contact  for 6,000 cycles at 50 mV s vs. RHE . The deg vs. RHE . Also ob vs. RHE . The ini vs. RHE .The start-stop durability LSVs of the catalysts before and after the tests are shown in Or4+ in PtO2, undergo dissolution faster than lower-order Pt species according to the equation.The presence of a facial layer of oxide on the surface due to the presence of terminal oxygen functional groups as shown in the O1s spectra of the HCSs is responsible for part of the degradation of the Pt. The formation of the Pt –O bonds weakens the pre-existing Pt–Pt bonds. As the PtO can be further oxidised, higher-order Pt oxidation states such as Pt.2+and subsequently Pt4+ as further Pt oxidation occurred. Notwithstanding the quantifiable oxygen functionalities on the HCSs and NHCSs supports, significant confinement of the Pt particles inside the pores reduced the rate of migration of dissolved and undissolved Pt particles to form larger Pt clusters.The oxidation state of the Pt particles is closely related to Pt dissolution and Ostwald ripening processes. The cathodic dissolution of the Pt particles is a thermodynamically feasible process that occurs below 0.837 V according to The shift in the LSVs is also observed in the changes in the MA and SA of the catalysts after durability tests . There ivia processes that include Pt dissolution, Ostwald ripening, agglomeration, particle detachment as well as support corrosion (DES), and as shown by The decline in MA was also coupled with a decline in SA. For the benchmark Pt/C, a 40% decline was observed compared to a 22.4% (Pt/HCSs) and 20.7% (Pt/NHCSs) decline for the two new catalysts. Degradation in fuel cells is known to occur orrosion . These pThe losses in ECSA, MA and SA were attributed to the agglomeration of Pt resulting in the formation of particles that are bigger and with less surface area. The growth in Pt particles can be seen from the comparison of the TEM images before and after stress testing . As show−1 from 1.0–1.6 V vs. RHE  for 6,000 cycles at 50 mV s vs. RHE . Under lEven though the thermodynamic potential for this process is lower , at highThe load cycling durability CVs shows a comparison between the before and after AST tests . The CVs2  as confirmed in the XPS C1s and O1s spectra. This presence results in the ease of interfacial oxidation of the thin layers of carbon. The low formation of the Q-HQ couple on the commercial benchmark could be attributed to the low BET surface area as a result of the carbon degradation to COEven though the double-layer capacitance and the features associated with the ECSA of the catalysts are reduced, due to degradation of the Pt/HCSs and the Pt/NHCSs catalysts, more degradation is observed for the commercial Pt/C catalyst . The AST2/g) and NHCSs (604 m2/g) supports both have a higher BET surface area and an array of mesopores and micropores which promotes the confinement of Pt particles, resulting in better support to metal contact. Also, confined Pt particles are more resistant to migration and agglomeration. The higher loss in activity of the benchmark Pt/C is ascribed to low pore confinement compared to the new materials. Pore confinement of the Pt in the structure of the HCSs based supports was confirmed in a similar study involving broken hemispherical hollow carbon spheres  analysis of the catalysts was studied. Analysis of the data revealed that the NHCSs showed increased buckling of the carbon plane compared to the pristine sample due to the nitrogen doping. Addition of Pt to the spheres also gave rise to a Pt-C interaction that could be detected by PDF analysis and the strength of the interaction of the Pt particles with the carbon surface is such that the larger the interaction the larger the C–C bond elongation. The stronger Pt-C interaction was responsible for part of the observed long-term durability of the Pt/HCSs and Pt/NHCSs catalysts.The PDF method is highly sensitive to small particles resulting in an accurate particle size determination. The higher proportion of smaller average Pt sizes as determined by the PDF technique compared to PXRD, could partly explain the higher activity in ORR observed for the Pt/HCSs and Pt/NHCSs.−1 from 0.6 to 1.0 V vs. RHE. The data showed that after 6,000 cycles, the ECSA retentions were Pt/C (47.6%) < Pt/NHCSs (62.1%) < Pt/HCSs (65.4%). In other experiments the start-stop durability LSVs of the catalysts, before and after the tests, was studied and the data revealed LSV shifts in the order Pt/HCSs (18 mV) < Pt/NHCSs (22 mV) < Pt/C (30 mV). A shift in LSVs is attributed to the loss of activity due to the degradation of the Pt catalysts. The losses in ECSA, MA (and SA) were attributed to the agglomeration of Pt and this agglomeration was detected by post analysis of the samples from TEM images.The Pt catalysts prepared by the ethanol reflux method demonstrated higher activity and durability than the commercial benchmark Pt. The durability the Pt catalysts were subjected to accelerated stress tests (AST) for 6,000 cycles at 50 mV sThe two effects of pore confinement and the presence of defects/nucleation sites is proposed to be responsible for the enhanced durability of the catalysts. Based on these findings, the Pt/HCSs and Pt/NHCSs are good candidates for PEMFC catalysts and strategies to further enhance the durability of the catalysts and reduce Pt use can be further initiated from the above studies.


However, it is still not completely understood how c-Myc functions in GC. Here, we generated a stomach-specific c-Myc transgenic mouse model to investigate its role in GC. We found that overexpression of c-Myc in +Atp4b gastric parietal cells could induce gastric adenoma in mice. Mechanistically, c-Myc promoted tumorigenesis through the AKT/ mammalian target of rapamycin (mTOR) pathway. Furthermore, AKT inhibitor (MK-2206) or mTOR inhibitor (rapamycin) inhibited the proliferation of c-Myc overexpressing GC cell lines and the initiation of gastric tumorigenesis in c-Myc transgenic mice. Thus, our findings highlight that gastric tumorigenesis can be induced by c-Myc overexpression through activation of the AKT/mTOR pathway.Gastric cancer (GC) is one of the most common malignant cancers in the world.  Gastric cancer (GC) is one of the most common malignant cancers in the world. It was reported that in 2018, the incidence of GC ranked the fifth in the world, while the mortality rate ranked the third , GC can Mouse model is commonly used to investigate the pathogenesis of various cancers since the protein-coding genes of mice and human share high similarity . Establic-Myc is a well-known oncogene involved in various cancers, including GC. Amplification of c-Myc in GC has been reported in several studies [c-Myc copies (≥3) is linked with late on-set, intestinal-type, advanced tumor stage, and distant metastasis, while c-Myc hypomethylation is associated with diffuse-type GC [c-Myc overexpression is more frequently observed in GC than gene amplification [c-Myc overexpression was described in over 40% of GC [c-Myc mRNA expression, which was associated with deeper tumor extension and metastasis [c-Myc is more frequently observed in intestinal-type GC than diffuse-type GC [c-Myc is sufficient to cause GC remains unclear.The  studies -11. Gain-type GC . It is rfication ,14. c-My0% of GC . De Souztastasis ,16. Nota-type GC ,17,18 an-type GC . MYC pro-type GC ,22. Howec-Myc plays a crucial role in several cellular functions, such as cell proliferation, differentiation, and cell cycle progression [Myc transcriptionally regulates the expression of TRAP1, which controls primary and metastatic tumor growth [Myc induces RCC in a glutamine-addicted way [c-MYC proteins, which is resulted from alterations of the Wnt and Ras pathways, is often seen in 70% colorectal cancer [BRD4 could promote GC progression through positive regulation of c-Myc in transcription and epigenetic levels [c-Myc could inhibit the growth and proliferation of GC cell lines [c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling pathways [in vitro and in vivo [Lats1 and Lats2 [Myc-driven mouse models of cancer, including prostate cancer [c-Myc on GC would be of great interest to uncover new therapies for GC.The gression . It was r growth . In renacted way . Signifil cancer -28. Whilc levels  and knocll lines ,31. Liu pathways . Xu et a in vivo . Choi etnd Lats2 . There he cancer  and renae cancer , but note cancer . Thus, ic-Myc is highly expressed in gastric parietal cells to investigate the definite role of c-Myc in GC. We present data indicating that these mice developed the phenotypic features of the gastric adenoma, with a step-wise tumorigenic progression from hyperplasia to metaplasia, dysplasia, and finally adenoma in gastric mucosa. Importantly, our findings highlight a mechanism by which gastric adenoma can be induced by stomach-specific c-Myc overexpression through activation of the AKT/mammalian target of rapamycin (mTOR) pathway.In this study, we generated a novel gastric tumor model in which human Atp4b-cre mice were gifted from Dr. Xiao Yang and described previously [fl/flMyc mice were purchased from the Jackson Laboratory and were also described previously [fl/+Atp4b-cre; Myc, referred as OEAtp4b-cre; Myc mice were generated by crossing Atp4b-cre mice with fl/flMyc mice. fl/flMyc mice were used as control. Both male and female mice were used for experiments since no difference of sex has been observed. All the mouse strains were generated in a C57BL/6 background and were born and maintained in a specific-pathogen-free (SPF) facility and all experimental procedures were approved by the Animal Ethics Committee of School of Biomedical Engineering and Med-X Research Institute, Shanghai Jiao Tong University. All institutional and national guidelines for the care and use of laboratory animals were followed. Primers for genotyping are shown in eviously . Mycfl/feviously . Atp4b-c2O2. Blocking was performed with 5% BSA for 1 hour at room temperature. The primary antibodies used here were anti-c-MYC , anti-Ki67 , anti-MUC2 , and anti-MUC5AC . Periodic Acid-Schiff/Alcian Blue (PAS/AB) staining was performed using AB/PAS stain kit . Staining intensities were calculated using Image J software.Mice were sacrificed at different ages . Mouse stomachs were then harvested, cut open through the greater curvature, and washed 3 times in phosphate-buffered saline by vigorous shaking. Tissues were fixed in 4% poly-formaldehyde for 24 hours at 4°C, then dehydrated and embedded in paraffin. Sections (5 μm) were cut and stained with H&E. Tumor grades (0-4) were scored according to the previous report . For IHCTissue and cell lysates were prepared by strong radioimmunoprecipitation assay buffer  containing protease inhibitors and supplemented with protein phosphatase inhibitors . The proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and then transferred to polyvinylidene fluoride membranes (Millipore). The membranes were blocked with 6% skim milk in Tris-Buffered Saline Tween-20 for 1.5 h at room temperature and subsequently incubated with specific primary antibodies overnight at 4°C followed by incubation with secondary antibodies for 1 h. The primary antibodies used in this study were as follows: Anti-flag-tag , anti-c-MYC , anti-β-Actin , anti-PI3K , anti-p-PI3K , anti-AKT , anti-p-AKT , anti-mTOR , anti-p-mTOR , and anti-GAPDH .p value was calculated using the Student’s t-test. The primers used in qPCR were listed in Total RNA was extracted from tissues using RNA extraction kit (Bioteke) following the manufacturer’s protocol. RNA was then reverse-transcribed with RT reagent kit . The cDNAs were subsequently subjected to SYBR Green-based real-time PCR analysis. GAPDH was used for normalization. Data were shown as average values ± standard error of the mean (SEM). The OEAtp4b-cre; Myc and wild type (WT) mice. Differential gene expression was analyzed using the DESeq2 package. The list of significance was determined by setting a false discovery rate (FDR) threshold at a level of <0.05 and |log2FC| of more than 0.585. All differentially expressed genes were subsequently analyzed for gene ontology (GO) and pathway analysis.Gastric mRNA was obtained from 12-week-old 2 atmosphere.AGS cell line was obtained from the American Type Culture Collection (ATCC) and cultured in RPMI-1640 supplemented with 10% fetal bovine serum (Thermo), 100 U/mL penicillin, and 0.1 mg/mL streptomycin (Thermo) at 37°C in a humidified 5% COc-Myc cDNA was generated by PCR and cloned into pCMV6-Entry vector with Myc-tag and flag-tag. The constructs generated were confirmed by DNA sequencing. For transient transfection, AGS cells were transfected with the jetPRIME® transfection reagent (Polyplus) according to the manufacturer’s instruction. Primers used for amplification of human c-Myc cDNA were as follows: Sense: 5’-AGTAAAGCTTATGGATTTTTTTCGGGTAGTGGAA-3’ and antisense: 5’-ATATACGCGTCGCACAAGAGTTCCGTAG-3’.Human 4 cells/well. After cultured for 4 hours, cells were treated with MK-2206 and rapamycin at a concentration of 10 uM and 25 uM, respectively. After cultured for 12 hours, 24 hours, 36 hours, and 48 hours, cells were incubated with CCK8 for 2 hours at 37°C. Cell proliferation was determined by measuring the optical density value at 450 nm using a microplate reader (BioTek).Cell counting kit-8 , being non-radioactive, allows sensitive colorimetric assays for the determination of the number of viable cells in cell proliferation and cytotoxicity assays. Cells that transfected for 24 hours were seeded in 96-well plates at a density of 1 × 10OEAtp4b-cre; Myc mice, at 7 weeks of age, were treated with two inhibitors, MK-2206 and rapamycin, 3 mice in each group. MK-2206  was prepared in 10% dimethyl sulfoxide (DMSO), 40% polyethylene glycol 300 (PEG300), 5% Tween-80, and 45% saline and administered to c-Myc transgenic mice by oral gavage at a dose of 100 mg/kg every other day for 2 weeks. Rapamycin  was prepared in 10% DMSO, 40% PEG300, 5% Tween-80, and 45% saline and administered to c-Myc transgenic mice by intraperitoneal injection at a dose of 5 mg/kg daily for 3 weeks. Mice were then sacrificed and stomachs were harvested for further HE staining.p < 0.05 was considered to be statistically significant. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001.All experiments were repeated at least three times. Unless otherwise indicated, data were presented as mean ± SEM and analyzed for statistical significance by Kruskal–Wallis or Mann–Whitney using GraphPad Prism 6 software or SPSS 19.0 software. RNA-Seq raw data have been deposited in the Gene Expression Omnibus (GEO) under accession number GEO: GSE145583.c-Myc in GC, we first generated a mouse model with Cre-dependent targeted overexpression of c-Myc. c-Myc-floxed mice were crossed with Atp4b-cre to obtain OEAtp4b-cre; Myc mice  in OEAtp4b-cre; Myc mice and PAS+ cells  in WT mice  were upregulated compared with WT mice. Notably, the RNA expression of Smad2/3/4, which is related to regulation of transcription, was significantly downregulated in c-Myc transgenic mice compared with WT mice. Furthermore, the RNA expression of Mcm2/Mcm5/E2f2, associated with cell cycle, was significantly upregulated in OEAtp4b-cre; Myc mice.To explore the potential mechanism underlying ed genes  and B. Aigenesis . RT-qPCRigenesis . As expec-Myc overexpression enriched genes correlated with the PI3K-Akt pathway and mTOR signaling  compared with WT mice  or an mTOR inhibitor (rapamycin). As shown by CCK8 assays, overexpression of c-Myc in AGS cells  were associated with malignant characteristics [c-Myc transgenic mice, and inhibition of AKT and mTOR can significantly decrease cell proliferation in AGS cells overexpressing c-Myc and inhibit or postpone the onset of gastric tumors in vivo. Importantly, our experiments demonstrate not only that c-Myc can be a driver for gastric adenoma but also that the AKT/mTOR pathway could be the underlying mechanism of gastric tumorigenesis caused by c-Myc overexpression.By the establishment of a conditional transgenic mouse model, we show that gastric adenoma induced by eristics . Activateristics , skin caeristics ,49, and eristics . It has eristics ,52. Our c-Myc gene can prompt the gastric tumorigenesis of transgenic mice toward a faster and more severe way. Based on our observation, 14-week-old fl/flAtp4b-cre; Myc mice exhibit submucosal invasion, while OEAtp4b-cre; Myc  mice do not at the same age. Similarly, in human GC, it is reported that increased Myc copy number is associated with a late-onset, intestinal-type cancer and the presence of distant metastasis [Atp4b-cre; fl/flMyc mice exhibit distant metastasis needs further investigation.It is worth pointing out that our study also shows an increased copy number of tastasis . Whetherc-Myc affects the development and progression of GC. More importantly, it will aid the clinical detection and therapeutic strategies for intervention at precancerous stages of GC so to improve patient survival.Taken together, we generated a novel autochthonous transgenic mouse model of gastric adenoma that is generally useful for studying the initiation and progression of GC. It provides a new platform to further study the roles of more genes involved in GC through combining with mutations in other genes. It will facilitate our better understanding of the development of early GC and shed light on the molecular mechanisms by which