•Nature-based green infrastructure is important to future ecological protection.•The FLUS model is well adapted to LULC simulation for sustainable urban sprawl scenario.•The improved framework can be ...promoted to construct the GI network in future.
Nature-based green infrastructure (GI) is considered as a sound solution to mitigate the urban issues resulting from rapid urbanization. It is exceedingly essential to construct GI network for adaption to the dynamics of natural and social conditions. However, it has not been well studied until now. In this study, taking Lanzhou City, Gansu Province, China as a case, we proposed an improved framework of GI construction for adaption to sustainable urban sprawl. First, we predicted the land use and land cover (LULC) in Lanzhou City in 2030 by using the FLUS (future land use simulation) model. Then, based on the predicted LULC, we extracted ecological sources and corridors by integrating MSPA (Morphological spatial pattern analysis) and MCR (minimum cumulative resistance) model. Finally, as a case, an optimized GI network for adaption to the future sustainable urban sprawl in Lanzhou City in 2030 was established, which included 10 ecological sources, 56 ecological corridors as well as 19 nodes. In this case study, the improved framework was proven to be reliable, and thus can be promoted to construct the GI network in other regions for adaption to different future scenarios. This case study would provide some new insights for future urban planning both in Lanzhou City and cities in other regions, and then contribute to GI protection and regional ecological security.
Land use and cover change (LUCC) is an important issue affecting the global environment, climate change, and sustainable development. Detecting and predicting LUCC, a dynamic process, and its driving ...factors will help in formulating effective land use and planning policy suitable for local conditions, thus supporting local socioeconomic development and global environmental protection. In this study, taking Gansu Province as a case study example, we explored the LUCC pattern and its driving mechanism from 1980 to 2018, and predicted land use and cover in 2030 using the integrated LCM (Logistic-Cellular Automata-Markov chain) model and data from satellite remote sensing. The results suggest that the LUCC pattern was more reasonable in the second stage (2005 to 2018) compared with that in the first stage (1980 to 2005). This was because a large area of green lands was protected by ecological engineering in the second stage. From 1980 to 2018, in general, natural factors were the main force influencing changes in land use and cover in Gansu, while the effects of socioeconomic factors were not significant because of the slow development of economy. Landscape indices analysis indicated that predicted land use and cover in 2030 under the ecological protection scenario would be more favorable than under the historical trend scenario. Besides, results from the present study suggested that LUCC in arid and semiarid area could be well detected by the LCM model. This study would hopefully provide theoretical instructions for future land use planning and management, as well as a new methodology reference for LUCC analysis in arid and semiarid regions.
According to Rabcewicz (1964, 1965), tunnels should be driven full face whenever possible. The pre-cutting method is a popular tunnelling method based on this idea. This method allows safe excavation ...even in poor ground conditions by creating continuous pre-arching around tunnel periphery in advance. Because of high costs and safety risk in field test, the previous studies on pre-cutting method are limited and qualitative, which mainly focused on its machine, construction procedure and applicable conditions. To further develop this method, systematic and quantitative studies on ground settlement and pre-arching stress caused by it are needed. In this study, a 1:10 geo-mechanical physical model test was performed to understand the mechanism of pre-cutting method by simulating its construction process. The ground settlement, earth pressure and pre-arching stress during tunnelling were investigated. Afterwards, three-dimensional numerical simulations were performed to simulate the process of physical model test so as to compare with experimental results. The effects of different pre-cutting parameters such as length, thickness, lap length and sequence of cutting slots, which can’t be sufficiently covered by the model test, were studied by numerical method. Comparative studies between pre-cutting and New Austrian Tunnelling Method (NATM) under the same geological conditions were also carried out. In general, the comparative analysis shows that the physical model test has achieved satisfactory results and the pre-cutting method has a great advantage in controlling ground deformation compared with NATM.
Long-term exposure to PM2.5 (fine particulate matter with an aerodynamic diameter <2.5 μm) could cause great harm to human health and sustainable development. It remains a challenge to estimate the ...long-term PM2.5 removal capacity of nature-based green infrastructure in urban areas. In this paper, the annual PM2.5 removal capacity of urban green infrastructure (UGI) from 2000 to 2019 in Shenyang was estimated based on the PM2.5 dry deposition model. The spatial heterogeneity of annual PM2.5 removal capacity were detected Sen-MK test and local spatial autocorrelations analysis. Then the effects of landscape patterns and socioeconomic variables on PM2.5 removal capacity were explored based on linear regression model. The results illustrated that the PM2.5 removal capacity of UGI increased significantly from 2000 to 2019 in Shenyang, with the amount of PM2.5 removal, PM2.5 removal flux and removal rate increasing by 20.64 Mg/a, 0.0258 g/m2/a, and 0.377 %/a, respectively. The PM2.5 removal capacity of UGI exhibited spatial heterogeneity in the study area. Specifically, the regions experiencing the increase in PM2.5 removal capacity of UGI accounted for majority of the old urban area of Shenyang City during the study period; the lower PM2.5 removal capacity clustered in the center urban area, in which high density impervious surfaces distributed, while the higher PM2.5 removal capacity mainly gathered in the area with large scale green space; PM2.5 removal capacity were significantly higher in urban functional zones with a high proportion of green spaces. The landscape metrics representing fragmentation and shape complexity positively affected the annual PM2.5 removal flux and removal rate, while the aggregation metrics had significantly negative correlations with the PM2.5 removal flux and removal rate. Moreover, it was also found that population density and GDP negatively affected the PM2.5 removal capacity of UGI. This study provides a methodological reference and some new insights for future urban landscape planning and air pollution purification.
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•The PM2.5 removal capacity of urban green infrastructure (UGI) has improved.•The spatial heterogeneity of the PM2.5 removal capacity was observed.•The PM2.5 removal capacity was profoundly affected by the landscape patterns of UGI.•Anthropogenic factors partly accounted for the heterogeneity of PM2.5 removal capacity.
Urban green infrastructure (UGI) is considered to be an effective tool for mitigating PM2.5 (particulate matter with an aerodynamic diameter of less than 2.5 μm) pollution in urban areas. However, ...long and continuous time series analyses of the relationships between the UGI landscape and PM2.5 pollution remain a challenge. In the present study, then we analyzed the PM2.5 variations and their relationships with the UGI landscape patterns at the urban agglomeration (the urban area of CLUA) and neighborhood scales (6 neighborhood zones with radii ranging from 500 m to 3000 m around the sampling point.). The results illustrated PM2.5 concentration increased slightly in the urban expansion areas and decreased in some old urban areas, but the changing trend was not significant. The PM2.5 concentrations were different among the four seasons in this area, and the lowest and highest concentrations occurred in winter (66.79 μg/m³) and summer (24.32 μg/m³), respectively. At the urban agglomeration scale, just a very small proportion of the PM2.5 variations in the CLUA during this study period could be attributed to the UGI landscape pattern, wind speed and relative humidity; PM2.5 concentrations were affected more strongly by wind speed and relative humidity than by UGI landscape patterns; the LSI (landscape shape index) and bridges served as the main landscape indicators affecting the PM2.5 concentrations among the UGI landscape patterns factors. At the neighborhood scale, the LPI (largest patch index), AWMSI (area-weighted mean shape index), AI (aggregation index), Core and Loop served as the main UGI landscape indicators influencing PM2.5 and had different degrees of influence on the PM2.5 concentrations; the seasonal and scale effects of UGI landscape patterns on PM2.5 concentrations at neighborhood scales were observed. Comparatively, the effects of the UGI landscape patterns on PM2.5 concentration seem more significant at the neighborhood scale than at the urban agglomeration scale. The findings of this multiscale analysis can provide new insights into understanding the relationships between UGI landscape patterns and urban air pollution at different scales, and provide a scientific reference for urban planning and air pollution control.
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•Nonsignificant changes in PM2.5 concentrations occurred in all urban areas of the CLUA.•PM2.5 variations was less attributed to the UGI landscape at the urban agglomeration scale.•Effects of UGI landscape on PM2.5 concentration was more significant at the neighborhood scale.•The seasonal and scale effects of UGI on the PM2.5 concentrations existed at neighborhood scales.
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The growing concern over the rapid consumption of fossil fuels has spurred scientists to seek environment-friendly and sustainable energy alternatives. The utilization of ...photocatalytic water splitting shows great potential in generating environmentally friendly hydrogen energy. Zirconium-based porphyrin MOF-545 has drawn extensive attention in photocatalysis since it has strong light absorption and fast electron transfer capability. A series of Zr-based metalloporphyrins containing different metals, MOF-545M (M = Co, Ni, Cu, Zn), were synthesized and assembled with solid solution ZnxCd1-xS (ZCS) nanoparticle to develop the corresponding of hybrid photocatalysts, ZCS/MOF-545M. Various characterizations show that introducing the porphyrin MOF-545Co not only improve the visible light response range of Zn0.5Cd0.5S (ZCS-0.5) but also enhance the carrier separation efficiency of ZCS-0.5. The carrier transfer direction during the reaction was confirmed by surface photovoltage spectroscopy and shows the formation of S-scheme. Under visible light irradiation, the hybrid photocatalyst ZCS-0.5/MOF-545Co exhibits a high H2 evolution rate of 148 μmol h−1, with increases of 52.8, 22.9 and 6.5 times than those of bare ZnS, CdS and ZCS-0.5, respectively. The present work gives a strategy for erecting S-scheme heterojunction to inhibit the photocorrosion of metal sulfides and enhancement the carrier separation efficiency.
Spatial transcriptomics (ST) has become a powerful tool for exploring the spatial organization of gene expression in tissues. Imaging-based methods, though offering superior spatial resolutions at ...the single-cell level, are limited in either the number of imaged genes or the sensitivity of gene detection. Existing approaches for enhancing ST rely on the similarity between ST cells and reference single-cell RNA sequencing (scRNA-seq) cells. In contrast, we introduce stDiff, which leverages relationships between gene expression abundance in scRNA-seq data to enhance ST. stDiff employs a conditional diffusion model, capturing gene expression abundance relationships in scRNA-seq data through two Markov processes: one introducing noise to transcriptomics data and the other denoising to recover them. The missing portion of ST is predicted by incorporating the original ST data into the denoising process. In our comprehensive performance evaluation across 16 datasets, utilizing multiple clustering and similarity metrics, stDiff stands out for its exceptional ability to preserve topological structures among cells, positioning itself as a robust solution for cell population identification. Moreover, stDiff's enhancement outcomes closely mirror the actual ST data within the batch space. Across diverse spatial expression patterns, our model accurately reconstructs them, delineating distinct spatial boundaries. This highlights stDiff's capability to unify the observed and predicted segments of ST data for subsequent analysis. We anticipate that stDiff, with its innovative approach, will contribute to advancing ST imputation methodologies.
There is a close relationship between tourism efficiency and transport accessibility, but there is little research on the topic. This paper takes 17 administrative units in Hubei Province as the ...research object, evaluates their tourism efficiency from 2011 to 2017 and transportation accessibility in 2011 and 2017, and explores the temporal and spatial correlation between the two. The results showed that, from 2011 to 2017, tourism efficiency of Hubei province was high and steadily improving, space non-equilibrium gradually decreased, and differences shrank. In 2011 and 2017, the province had a good tourism transport accessibility, and the spatial distribution pattern was high in the east and low in the west. At the same time, tourism transport continued to improve, and spatial imbalance declined. In 2011 and 2017, the coupling and coordination of tourism efficiency and its decomposition efficiency and transport accessibility in Hubei Province were both good, indicative of the development of a tourism economy and the improvement of tourism transport facilities in all regions of the province. There is also a poor spatial matching of tourism efficiency and its decomposition efficiency with transport accessibility during the study period. This study suggested that the tourism efficiency and transport accessibility increased in Hubie province, but the coupling and spatial match remain not very good. Therefore, each region should improve the spatial match and coupling degree of tourism efficiency and transport accessibility, and enhance the sustainability of tourism development.
Piezocatalysis is a direct method for converting mechanical vibration into chemical energy. Herein, NiTiO
3
is used in the piezocatalytic hydrogen evolution field for the first time. The noncentral ...symmetry of NiTiO
3
is enhanced by doping with large radius elements. It is demonstrated that when a metal element replaces the sites of nickel, it results in lattice distortion and a higher piezoelectric response. In particular, Cd-doped NiTiO
3
exhibits the highest H
2
generation rate (1.52 mmol g
−1
h
−1
), which is 13 times that of original NiTiO
3
.
Piezocatalysis is a direct method for converting mechanical vibration into chemical energy.
Piezocatalysis is a direct method for converting mechanical vibration into chemical energy. Herein, NiTiO
is used in the piezocatalytic hydrogen evolution field for the first time. The noncentral ...symmetry of NiTiO
is enhanced by doping with large radius elements. It is demonstrated that when a metal element replaces the sites of nickel, it results in lattice distortion and a higher piezoelectric response. In particular, Cd-doped NiTiO
exhibits the highest H
generation rate (1.52 mmol g
h
), which is 13 times that of original NiTiO
.
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