Just Accepted
By simplifying catalyst–product separation and reducing phosphorus waste, heterogeneous hydroformylation offers a more sustainable alternative to homogeneous processes. However, heterogeneous hydroformylation catalysts developed thus far still suffer from the issues of much lower activity and metal leaching, which severely hinder their practical application. Here, we demonstrate that incorporating phosphorus (P) atoms into graphitic carbon nitride (PCN) supports facilitates charge transfer from Rh to the PCN support, thus largely enhancing electronic metal–support interactions (EMSIs). In the styrene hydroformylation reaction, the activity of Rh1/PCN single-atom catalysts (SACs) with varying P contents exhibited a volcano-shaped relationship with P doping, where the Rh1/PCN SAC with optimal P doping showed exceptional activity, approximately 5.8- and 3.3-fold greater than that of the Rh1/g-C3N4 SAC without P doping and the industrial homogeneous catalyst HRh(CO)(PPh3)3, respectively. In addition, the optimal Rh1/PCN SAC catalyst also demonstrated largely enhanced multicycle stability without any visible metal aggregation owing to the increased EMSIs, which sharply differed from the severe metal aggregation of large nanoparticles on the Rh1/g-C3N4 SAC. Mechanistic studies revealed that the enhanced catalytic performance could be attributed to electron-deficient Rh species, which reduced CO adsorption while simultaneously promoting alkene adsorption through increased EMSIs. These findings suggest that tuning EMSIs is an effective way to achieve SACs with high activity and durability.
Dual-comb spectroscopy (DCS) is one of the most promising technologies for ultra-long open-path multiple greenhouse gas detection. Ultra-long open-path DCS has the potential to realize detection configurations, such as horizontal open-path links over hundreds of kilometers and vertical open-path links between satellites and the ground base. Under these extreme detection conditions, identifying an appropriate wavelength band that ensures both technical feasibility and a reasonable absorbance for target components is critical but currently lacks studies. In this work, we simulate transmission spectra under different detection configurations to identify optimal wavelength bands for CO2 and CH4 measurement. The simulation results show that the
The dynamics of water availability within a region can be quantitatively analyzed by partitioning the water into blue and green water resources. It is widely recognized that vegetation is one of the key factors that affect the assessment and modeling of blue and green water in hydrological models. However, SWAT-EPIC has limitations in simulating vegetation growth cycles in subtropics because it was originally designed for temperate regions and naturally based on temperature. To perform a correct and realistic assessment of changing vegetation impacts on modeling blue and water resources in the SWAT model, an approach was proposed in this study to modify the SWAT plant growth module with the remotely sensed leaf area index (LAI) to finally solve problems in simulating subtropical vegetation growth, such as controlling factors and dormancy. Comparisons between the original and modified model were performed on the model outputs to summarize the spatiotemporal changes in hydrological processes (including rainfall, runoff, evapotranspiration and soil water content) under six different plant types in a representative subtropical watershed of the Meichuan Basin, Jiangxi Province. Meanwhile, detailed analysis was conducted to discuss the effectiveness of the modified SWAT model and the impacts of vegetation changes on blue and green water modeling. The results showed that (1) the modified SWAT produced more reasonable seasonal curves of plants than the original model. ENS (Nash-Sutcliffe efficiency) and R2 increased by 0.02 during the calibration period and accounted for an increase of 0.09 and 0.03, respectively, during the validation period. (2) The comparison of model outputs between the original and modified SWAT suggested that evapotranspiration was more sensitive to vegetation changes than other components of green water. In addition, vegetation presented conservation capability in the blue water. (3) The variation in blue and green water resources with different plant types after modifying the SWAT model showed that seasonal changes in vegetation led to a significant difference between forest and non-forest areas.
ZnO thin films with varying Ta concentrations were fabricated through magnetron sputtering. The crystallinity and surface morphology of the ZnO films are significantly influenced by the incorporation of Ta, as evidenced by the X-ray diffraction and scanning electron microscopy results. The lattice constants, as determined by X-ray diffraction, contradict the disparity in Ta and Zn ion radii, which is attributed to the impact of interstitial defects. This inconsistency introduces variations in carrier concentration in this experiment compared with prior studies. Subsequent exploration of the luminescent characteristics and emission mechanism of defect levels in Ta-doped ZnO films was conducted through photoluminescence. Furthermore, the factors influencing the bandgap are discussed.
Advertising avoidance is resistance to advertising intrusion. This issue has been the subject of much academic research in recent years. To guide future scholars to better carry out relevant research and promote enterprises to better implement advertising activities, this study intends to summarize the relevant research on advertising avoidance in recent years. The specific method is to use the core literature meta-analysis method to identify, filter and screen relevant literature published in core journals from 1997 to 2020 with the keywords advertising avoidance and advertising resistance. We review the collected articles from the perspectives of external stimulating factors of advertising avoidance, internal perception factors of advertising avoidance, and moderating factors of advertising avoidance. On this basis, the SOMR model of advertising avoidance is constructed according to the SOR model. Finally, some prospects for future related research are given.
Near-field ground motion amplification at sedimentary basins is widely observed and crucial to the earthquake hazard assessment. However, the effect of basin topography coupling with the low-velocity layer (LVL) in the ground motion amplification is yet to be fully understood. By constructing 3D basin models with surrounding mountain terrains and performing ground motion simulations, we compare the ground motion characteristics with different basin LVL depths and LVL velocities. The velocity contrast between LVL and bedrock controls the amplification magnitude. The maximum amplification area in the model changes from the central part to the periphery part of the basin with the velocity contrast decreasing and can be greatly influenced by the distance between the source and the basin. Amplification also spreads along the mountain edge circling the basin. Our work sheds light on the distribution of amplification within sedimentary basins surrounded by mountains, revealing that the velocity contrast between the LVL and bedrock plays a pivotal role in controlling the magnitude of amplification.
Social interaction with peer pressure is widely studied in social network analysis. Game theory can be utilized to model dynamic social interaction and one class of game network models assumes that peopleos decision payoff functions hinge on individual covariates and the choices of their friends. However, peer pressure would be misidentified and induce a non-negligible bias when incomplete covariates are involved in the game model. For this reason, we develop a generalized constant peer effects model based on homogeneity structure in dynamic social networks. The new model can effectively avoid bias through homogeneity pursuit and can be applied to a wider range of scenarios. To estimate peer pressure in the model, we first present two algorithms based on the initialize expand merge method and the polynomial-time two-stage method to estimate homogeneity parameters. Then we apply the nested pseudo-likelihood method and obtain consistent estimators of peer pressure. Simulation evaluations show that our proposed methodology can achieve desirable and effective results in terms of the community misclassification rate and parameter estimation error. We also illustrate the advantages of our model in the empirical analysis when compared with a benchmark model.
Most previous studies on surface PM2.5 concentrations over East Africa focused on short-term in situ observations. In this study, the WRF-Chem model combined with in situ observations is used to investigate the seasonal variation in surface PM2.5 concentrations over East Africa. WRF-Chem simulations are conducted from April to September 2017. Generally, the simulated AOD is consistent with satellite retrieval throughout the period, and the simulations depicted the seasonal variation in PM2.5 concentrations from April to September but underestimated the concentrations throughout the period due to the uncertainties in local and regional emissions over the region. The composition analysis of surface PM2.5 concentrations revealed that the dominant components were OIN and OC, accounting for 80% and 15% of the total concentrations, respectively, and drove the seasonal variation. The analysis of contributions from multiple physical and chemical processes indicated that the seasonal variation in surface PM2.5 concentrations was controlled by the variation in transport processes, PBL mixing, and dry and wet deposition. The variation in PM2.5 concentrations from May to July is due to wind direction changes that control the transported biomass burning aerosols from southern Africa, enhanced turbulent mixing of transported aerosols at the upper level to the surface and decreased wet deposition from decreased rainfall from May to July.
