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The negative impacts of urban land expansion on ecosystem services have been confirmed by many studies; however, there has been a lack of studies examining the impacts of urban expansion on ecosystems from an efficiency perspective. China is increasingly emphasising the efficiency of development systems by maximising economic, social, and environmental benefits from limited land resources, which is a vital issue for high-quality urban development. Therefore, this paper aims to explore the evolutionary characteristics of urban land expansion efficiency (ULEE) and its impact on ecosystem services (ESs) to improve the ecological functions of urban systems. We first analysed the influence mechanism, based on efficiency and land use theory. Then, we used the Super-SBM and the InVEST model to measure ULEE and ecosystem service value (ESV). Finally, through regression analysis we explored the actual characteristics of the influence of ULEE on ESs. The results show: (1) ULEE positively influences ESs, and the influence mediators include three main aspects, i.e., land use structure, land use pattern, and land use quality. (2) The ULEE of the urban agglomerations exhibited a fluctuating downward trend from 2006–2020, and noticeable spatial differences were observed. (3) The AESV of the three major urban agglomerations showed a decreasing trend during the study period, with the UA-MRYR being higher than UA-YRD and UA-CY. Meanwhile, a certain degree of coincidence between the changing trend of AESV and ULEE was apparent. (4) A positive correlation was found between ULEE and the ESV of the three urban agglomerations. That is, the enhancement of ULEE was found to catalyse the improvement of ESs. The impact of ULEE on ESs exhibited a general decreasing trend from east to west. These results complement the study of the territorial system of the human–land relationship and have essential reference value for sustainable urban development and ecological restoration. [ABSTRACT FROM AUTHOR]

Forecasting stock returns is extremely challenging in general, and this task becomes even more difficult given the turbulent nature of the Chinese stock market. We address the stock selection process as a statistical learning problem and build cross-sectional forecast models to select individual stocks in the Shanghai Composite Index. Decile portfolios are formed according to rankings of the forecasted future cumulative returns. The equity market's neutral portfolio—formed by buying the top decile portfolio and selling short the bottom decile portfolio—exhibits superior performance to, and a low correlation with, the Shanghai Composite Index. To make our strategy more useful to practitioners, we evaluate the proposed stock selection strategy's performance by allowing only long positions, and by investing only in A-share stocks to incorporate the restrictions in the Chinese stock market. The long-only strategies still generate robust and superior performance compared to the Shanghai Composite Index. A close examination of the coefficients of the features provides more insights into the changes in market dynamics from period to period. [ABSTRACT FROM AUTHOR]

The outbreak of COVID-19 has caused concerns globally. To reduce the rapid transmission of the virus, strict city lockdown measures were conducted in different regions. China is the country that takes the earliest home-based quarantine for people. Although normal industrial and social activities were suspended, the spread of virus was efficiently controlled. Simultaneously, another merit of the city lockdown measure was noticed, which is the improvement of the air quality. Contamination levels of multiple atmospheric pollutants were decreased. However, in this work, 24 and 14 air fine particulate matter (PM 2.5) samples were continuously collected before and during COVID-19 city lockdown in Linfen (a typical heavy industrial city in China), and intriguingly, the unreduced concentration was found for environmentally persistent free radicals (EPFRs) in PM 2.5 after normal life suspension. The primary non-stopped coal combustion source and secondary Cu-related atmospheric reaction may have impacts on this phenomenon. The cigarette-based assessment model also indicated possible exposure risks of PM 2.5 -bound EPFRs during lockdown of Linfen. This study revealed not all the contaminants in the atmosphere had an apparent concentration decrease during city lockdown, suggesting the pollutants with complicated sources and formation mechanisms, like EPFRs in PM 2.5 , still should not be ignored. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper constructs a comprehensive evaluation system of human settlements focusing on housing conditions, urban natural environments, social economy, and public infrastructure. Principal Component Analysis and Cluster Analysis are used to analyze and rank the 2003–2013 human settlements index and create five clusters for 35 major cities in China (including municipalities, provincial capitals, and Prefecture-level cities). On the basis of four years of a spatial analysis of the human settlements index, we find that living conditions of 35 Chinese cities have significantly improved; severe air pollution persists in China, with large differences between the north and the south; weak correlation between urban human settlements and the growth rate of economic development; and the infrastructure of China's mega cities is overloaded. The results confirm and quantify growing geographic disparities and deep structural urban challenges that are associated with rapid economic growth and social change, leaving many cities in China to struggle with worsening pollution, excessive demand on existing infrastructures, and housing prices that rise faster than disposable incomes. [ABSTRACT FROM AUTHOR]

As one of the most important transportation hubs and industrial bases in China, Zhengzhou has suffered from serious PM 2.5 pollution for a long time. However, the investigation of contamination status and possible exposure risks of environmentally persistent free radicals (EPFRs) in PM 2.5 from Zhengzhou is rare. In this work, a comprehensive study of pollution levels, seasonal variations, sources, and potential health risks of PM 2.5 -bound EPFRs in Zhengzhou was conducted for the first time. The atmospheric concentrations of EPFRs in PM 2.5 from Zhengzhou ranged from 1.732 × 10 12 spin m -3 to 7.182 × 10 14 spin m -3 between 2019 and 2020. Relatively serious contamination was noticed in winter and spring. Primary fossil fuel combustion and Fe-mediated secondary formation were apportioned as possible sources of PM 2.5 -bound EPFRs in Zhengzhou. Moreover, to avert the bias of the toxicity assessment induced by utilization of incompletely extracted EPFRs from sample filter, simulatively generated EPFRs were applied to toxicological evaluations (cell viability and reactive oxygen species assays). Corresponding experimental dosages were based on the estimated adults' annual exposure amounts of EPFRs in real PM 2.5 samples. The results elucidated that EPFRs might cause growth inhibition and oxidative stress of human lung cells, suggesting the possible exposure-induced health concerns for local people in Zhengzhou. This study provides practical information of real contamination status of PM 2.5 -bound EPFRs in Zhengzhou, which is favorable to local air pollution control and reduction of exposure risks on public health in central China., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Spatio-temporal epidemic simulation, assessment, and risk monitoring serve as the core to establishing and improving the national public health emergency management system. In this study, we investigated Oncomelania hupensis breeding grounds and analyzed the locational and environmental preferences of snail breeding in Dongting Lake (DTL), Hunan, China. Using geographic information systems and remote sensing technology, we identified schistosomiasis risk areas and explored the factors affecting the occurrence and transmission of the disease. Several key conclusions were drawn. (1) From 2006 to 2016, the spatial change of potential O. hupensis breeding risk showed a diminishing trend from the eastern and northern regions to southwest DTL. Environmental changes in the eastern DTL region resulted in the lakeside and hydrophilic agglomerations of the O. hupensis populations. The shift in snail breeding grounds from a fragmented to centralized distribution indicates the weakening mobility of the O. hupensis population, the increasing independence of solitary groups, and the growing dependence of the snail population to the local environment. (2) The spatial risk distribution showed a descending gradient from west Dongting area to the east and an overall pattern of high in the periphery of large lakes and low in other areas. The cold-spot areas had their cores in Huarong County and Anxiang County and were scattered throughout the peripheral areas. The hot-spot areas had their center at Jinshi City, Nanxian County, and the southern part of Huarong County. The areas with increased comprehensive risks changed from centralized and large-scale development to fragmented shrinkage with increased partialization in the core area. The risk distribution's center shifted to the northwest. The spatial risk distribution exhibited enhanced concentricity along the major axis and increased dispersion along the minor axis.