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Lithium–sulfur batteries (LSBs) have attracted considerable attention due to their high capacity and energy density, however, the electrochemical performance of LSBs was limited by the difficult conversion of lithium polysulfides (LiPSs). Coordination supramolecular networks (CSNs) have flexible structures, abundant active sites, and intermolecular interactions, which can facilitate the transformation of LiPSs and ion/charge transport. Herein, we combined a zinc coordination supramolecular network (Zn-CSN) with MnO2 to synthesize Zn-CSN@MnO2via a one-pot method. Zn-CSN@MnO2 accelerates the evolution of LiPSs and promotes the migration of lithium ions. Zn-CSN@MnO2 as a sulfur host in LSBs displays outstanding rate performance (406.55 mAh g−1 at 4C). It has a high initial specific capacity of 1027.89 mAh g−1 at 0.5C, cycling 150 cycles with a capacity loss of 0.2% per cycle. Surprisingly, it runs 400 cycles at a high current density of 5C with a capacity retention of 80.5%. This synergistic strategy for CSNs and oxides has brightened the prospects of the practical applications of LSBs. [ABSTRACT FROM AUTHOR]

Land-use conflicts (LUCs) are pivotal in assessing human–land interaction, reflecting the intricate interplay between natural and anthropogenic drivers. However, existing studies often overlook nuanced non-linear responses and critical threshold recognition, focusing solely on linear correlations between isolated factors and LUCs. This study, situated in Xinjiang, China's arid and semiarid region, introduces a novel analytical framework and threshold application model for LUCs. Integrating land-use and socioeconomic data, we quantified LUCs using Fragstats, correlation analysis, and restricted cubic spline (RCS) regression. Exploring non-linear dynamics between LUCs and 14 potential drivers, including natural and anthropogenic factors, we identified critical thresholds. LUC zones were delineated using a four-quadrant method, allowing tailored mitigation strategies. Our findings reveal Xinjiang's distinct LUC spatial pattern, with intense conflicts surrounding mountainous areas and milder conflicts in basin regions, showing marked diminishment from 2000 to 2020. RCS effectively identifies LUC thresholds, indicating persisting severity pre- or post-specific thresholds. Xinjiang's LUCs are categorized into key control areas, urgent regulation zones, elastic development territories, and moderate optimization regions, each with significant regional disparities. Tailored optimization suggestions mitigate linear analysis limitations, providing a fresh perspective on land zoning optimization. This research supports comprehensive land management and planning in Xinjiang, China. [ABSTRACT FROM AUTHOR]

The tertiary industry has become the main driving force for China's economic development, and the adjustment and optimization of its structure are important prerequisites for achieving high-quality economic development. Existing studies have mostly focused on the spatial layout and influencing factors of the tertiary industry, with insufficient exploration of its internal structure. In this study, the PRD urban agglomeration is selected as the study area. On the basis of classifying the tertiary industry, the Dagum Gini coefficient, kernel density estimation, and local spatial autocorrelation are used to explore the spatial differentiation of various tertiary industries. The influencing factors are analyzed using geographical detectors, and suggestions for future development strategies are proposed. The results show that in terms of regional differentiation, the agglomeration of various tertiary industries in Guangzhou and Shenzhen is the most significant, but there is insufficient spillover to surrounding cities. In terms of development structure, the level of agglomeration of the consumptive tertiary industry is higher, the public tertiary industry tends to be more evenly distributed, and the productive tertiary industry is relatively dispersed. In terms of influencing factors, the interaction between population and employment dominates the spatial differentiation and evolution of the tertiary industry in the PRD urban agglomeration. Therefore, in the future, the tertiary industry in PRD urban agglomeration should promote the optimization of industrial structure and regional coordinated development under the guidance of the government. [ABSTRACT FROM AUTHOR]

The distribution pattern of high-level tourist attractions is crucial for the sustainable development of the tourism industry. However, few studies have explored the spatial distribution and dominant influencing factors of tourist attractions of different levels from a macro perspective in China. This study, which was based on large-scale multi-source data, involved the use of kernel density analysis, local spatial autocorrelation, and geographical detector analysis to explore the spatial distribution, spatial correlation, and dominant influencing factors of high-level tourist attractions in China. The study's results show that the spatial distribution of tourist attractions of different levels is polarized and regionally clustered, and there exist some spatial correlation effects among attractions of the same level. Additionally, different influencing factors play a different role in determining the spatial distribution of attractions of different levels. Based on market demand and tourism resources, it is necessary to regulate attractions of different levels to promote the sustainable development of high-level tourist attractions and provide a reference for the development of China's tourism industry. [ABSTRACT FROM AUTHOR]

The variation in the urban spatial structure (USS) has profound impacts on carbon emissions. Studying the relationship between the two can provide guidance for carbon neutrality strategies and the construction of low-carbon cities in China. However, there is currently a lack of comparative research on the different regions within a province. In this paper, the spatiotemporal evolution of the USS and carbon emissions, at five-year intervals from 2000 to 2020, is investigated in 21 prefecture-level cities in Guangdong Province, China, and the overall relationship of the USS to carbon emissions and their spatiotemporal variations are analyzed by using a two-way fixed-effects model and a geographically and temporally weighted regression model, respectively. The results show that, first, over the past twenty years, the scale of cities has continued to expand, with increasing continuity and aggregation in the built-up areas, while the complexity and fragmentation of their shapes have gradually decreased. Second, the gap in carbon emissions between the Pearl River Delta and other regions in Guangdong shows a trend of first decreasing and then increasing, with high values concentrated in the Pearl River Delta region and the city of Shantou in the east. Third, compared to socio-economic factors, the USS has a more direct and pronounced impact on carbon emissions. Urban expansion and the increased complexity of land patches promote carbon emissions, whereas improving urban spatial continuity and compactness can reduce carbon emissions. Fourth, the dominant spatial structure indicators of carbon emissions differ among the regions of eastern, western, and northern Guangdong and the Pearl River Delta. This study proposes spatial optimization strategies for the low-carbon development of cities in Guangdong Province, providing a new perspective for integrating urban layout and emission reduction policies. [ABSTRACT FROM AUTHOR]

A comprehensive and scientific recognition and evaluation of landscape resources is an important prerequisite for the sustainable development of global geoparks, but the existing research lacks specific means and methods. In the case of the Koktokay Global Geopark (GGp), for example, in this study, we used GIS spatial analysis, SBE, and a questionnaire survey method to construct a comprehensive evaluation path and method for an audio-visual landscape for global geoparks and further built an audio-visual preference matrix. The research results show the following: (1) The Shenzhong Canyon scenic area has the best visual evaluation effect, whereas the Golden Triangle has the worst evaluation effect. (2) Tourists are generally satisfied with the soundscapes of the ten scenic locations in the Koktokay GGp. In addition, tourists do not think that a higher or lower volume of a soundscape would make their experience more comfortable or pleasant, so an increase in the threshold value of the sound level to a level that tourists can bear while traveling is possible. (3) The Shenzhong Canyon area is located in the key landscape area; the Aiguzi Mine and Cocosuri are located in the landscape natural development area; the No. 3 Mine Pit, Eremu Lakes, the Golden Triangle, and the Karadrola Falls are located in the landscape subpriority improvement area; and the Waterfall Fossil, Betula Forest, and Karashanger Earthquake Fault Zone are located in the landscape priority improvement area. The comprehensive audio-visual landscape evaluation method constructed in this study provides a methodological tool for evaluating other similar landscapes and provides professional guidance for the protection and development of geoparks. [ABSTRACT FROM AUTHOR]

Urban agglomeration (UA) is an advanced spatial economic form formed and developed in the process of rapid industrialization and urbanization, and an important carrier of urbanization and economic development. The economy has developed rapidly in the recent decades of China, and the UAs have also developed rapidly. However, as a large population country, the population distribution and changes of UAs in China has unique characteristics. Using the fifth, sixth and seventh population census data, spatial auto-correlation and spatial econometric models, we analyzed the spatial-temporal evolution characteristics and influencing factors of population agglomeration in China's UAs. Results revealed that: 1) from 2000 to 2020, the population gradually converged into UAs, and the characteristics of population agglomeration in different development degree of UAs differ. The higher the development degree of UA, the higher the population agglomeration degree. Besides, UAs are the main area with the most significant population agglomeration degree, and the spatial autocorrelation show that the cities with similar degree tend to be concentrated in space. The urban population gathering in UAs has a certain positive spillover effect on population size of neighboring cities. 2) Economic development and social conditions factors are important factors affecting population agglomeration degree in UAs. The main factors of population gather into UAs are similar with the outside UAs, but the positive promotion of urbanization rate and proportion of tertiary industry in GDP on population agglomeration of UAs in China are enhancing from 2000 to 2020. Meanwhile, the other factors, such as high-quality public services, good urban living environment conditions, high-quality medical and educational resources, are also important factors to promote urban population gather into UAs. This study provides a basis for formulating the development planning of UAs in China, and enriches the relevant theoretical research of population evolution and influencing factors of UAs. [ABSTRACT FROM AUTHOR]

Although high-quality tourism destinations directly determine the tourism experiences of tourists and the management focuses of tourism management departments, existing studies have paid little attention to the relationship between tourism destinations of differing quality and tourist experiences. This study analyzed the spatiotemporal distribution of tourists and the quality of tourism destinations in Urumqi based on Tencent migration big data and Weibo sign-in big data and ultimately determined whether there are spatial correlations between the two. The results show that there are large differences in quality between different tourist destinations, and although the spatial and temporal distribution of tourists is not strongly correlated with the quality of tourist destinations, we can divide tourist destinations into four categories based on the correlations between the two (e.g., high-quality tourist destinations with a low number of tourists). The results of this study provide tourists with examples of high-quality tourist destinations, thus improving their holiday experiences, and they also provide a basis by which tourism management departments can manage and develop tourist destinations. The results of this study can also be extended to other regions and play a positive role in promoting the development of the tourism industry. [ABSTRACT FROM AUTHOR]

China's urban agglomerations (UAs) are striving to build a new development pattern oriented towards the new era and new stage, and the population distribution is facing new problems of synergy with the layout of labor factor productivity and regional coordinated development. Therefore, this study couples UAs with population distribution, using data from three population censuses and nighttime light data in 2000, 2010, and 2020, to measure the population agglomeration patterns of Chinese UAs using population agglomeration indicators and to explore the influencing factors and spatial stratification heterogeneity characteristics by constructing an econometric model. The results show that: (1) the population agglomeration patterns of Chinese UAs can be classified into four major categories: weakly polycentric, weakly monocentric, strongly monocentric, and strongly polycentric UAs, and China's UAs are in a low-level stage dominated by weakly polycentric UAs at present. (2) In terms of influencing factors, 15 indicators, such as economic development and social conditions, are important factors affecting the population agglomeration patterns of the four UAs, but their effects vary greatly due to specific patterns. (3) For specific agglomeration models, the total passenger volume has always been the strongest positive influencing factor for weakly polycentric UAs; the industry location entropy index, scale of fiscal expenditure, and total passenger volume in municipal districts are relatively strong positive effects to weakly monocentric UAs, the per capita GDP and urbanization rate are relatively strong positive effects to strongly monocentric UAs, and the urbanization rate is always the strongest positive effect to strongly polycentric UAs. The refined analysis of population migration in Chinese UAs in this study enriches the theoretical results related to population migration in Chinese UAs to a certain extent and provides a feasible basis for the development of new development patterns in Chinese UAs and the formulation of regional population policies in the new stage. Meanwhile, this study divided the polycentric attributes of different UAs, which provide a reference for the theoretical development of polycentric spatial structure of UAs. [ABSTRACT FROM AUTHOR]

The digital economy plays an important role in the high-quality development of cities, and low-carbon urban development is an integral part of this evolution. Therefore, it is important to explore the impact of the development of the digital economy on urban carbon emissions. By considering 21 cities in Guangdong Province as the object of the research, this study measured the levels of the digital economy from 2011 to 2019 by using an entropy weight-based TOPSIS model, analyzed the spatiotemporal changes, and used geographically and temporally weighted regression to examine the spatiotemporal heterogeneity of the impact of the digital economy on urban carbon emissions. The results showed the following: (1) The development of the digital economy in Guangdong Province in general exhibited a stable trend of growth, and the average level of its development in the 21 cities considered increased by 3.4 times during the study period. (2) The level of development of the digital economy in the Pearl River Delta was significantly higher than that in northern, western, and eastern Guangdong, with Shenzhen being the most developed city in this regard (0.8473), and Shanwei being the least developed (0.0633). (3) The impact of the development of the digital economy on carbon emissions had significant spatiotemporal heterogeneity. The benefits of the development of the digital economy in terms of a reduction in carbon emissions was the most significant in the Pearl River Delta, and regional differences were prominent. (4) The reductions in carbon emissions in cities with a highly developed digital economy were more significant than has been reported in past studies in the area. However, it had a negative effect on the urban carbon emissions in cities with a poorly developed digital economy. The results of this study can be used to guide policies related to the high-quality development of the urban digital economy. [ABSTRACT FROM AUTHOR]

The vigorous development of information and communications technology has accelerated reshaping of the financial industry. The COVID-19 pandemic has further catalyzed the demand for digital financial services. Digital financial inclusion relies on information technology to overcome spatial limitations. In this case, the research question is whether it adheres to the spatial laws governing conventional financial activities. This study uses exploratory spatial data analysis and a geographical detector to elucidate the spatiotemporal characteristics and factors influencing digital financial inclusion at the county level in China (Data don't include that of Hong Kong, Macao and Taiwan of China) from 2014 to 2020. The research findings indicate: first, China's county-level digital financial inclusion is generally increasing and exhibits significant spatial autocorrelation. Second, population density, level of traditional financial development, government regulation, and education level are key determinants of China's county-level digital financial inclusion. Third, policies should be differentiated by region to narrow the spatial gap in digital financial inclusion. The results provide a reference for other developing countries on using digital technology to develop financial inclusion. [ABSTRACT FROM AUTHOR]

Migrant workers moving to urbanized areas constitute a floating labor pool that provides flexible and cheap labor for urbanization processes. The Thirteenth National People's Congress of the People's Republic of China proposed the "acceleration of citizenization of rural migrant workers". Promoting the citizenization of migrant workers has always been a focus of the government and aca-demia as well as a fundamental part of China's new urbanization strategy. Based on the questionnaire data of 1 270 migrant workers of the Pearl River Delta in 2017, this paper adopts the multinomial Logistic regression analysis to explore the residential choice and influencing factors among four types of migrant workers' families, which are childless family (I), parents and minor children combined family (ii), unmarried children and their parents combined family (iii), and empty-nest family (iV), from the perspective of the family life cycle. The results show that: 1) The average age, the length of residence, the level of education, the average monthly income, and the per capita living area of the four types of families show regular differentiation. 2) The residential choice of 4 types of families is mainly in urban villages; Types I and IV prefer to select factory dormitories and affordable housing communities, respectively, while types II and III prefer to select commodity housing communities. 3) The main influencing factors of the residential choice of migrant workers in the Pearl River Delta are family type, individual factor, rural factor, migration factor, and location factor. Based on the results of this study, we put forward community-based policy suggestions for citizenization strategy [ABSTRACT FROM AUTHOR]

Migrant workers moving to urbanized areas constitute a floating labor pool that provides flexible and cheap labor for urbanization processes. The Thirteenth National People's Congress of the People's Republic of China proposed the "acceleration of citizenization of rural migrant workers". Promoting the citizenization of migrant workers has always been a focus of the government and academia as well as a fundamental part of China's new urbanization strategy. Based on the questionnaire data of 1 270 migrant workers of the Pearl River Delta in 2017, this paper adopts the multinomial Logistic regression analysis to explore the residential choice and influencing factors among four types of migrant workers' families, which are childless family (I), parents and minor children combined family (II), unmarried children and their parents combined family (III), and empty-nest family (W), from the perspective of the family life cycle. The results show that: 1) The average age, the length of residence, the level of education, the average monthly income, and the per capita living area of the four types of families show regular differentiation. 2) The residential choice of 4 types of families is mainly in urban villages; Types I and IV prefer to select factory dormitories and affordable housing communities, respectively, while types II and III prefer to select commodity housing communities. 3) The main influencing factors of the residential choice of migrant workers in the Pearl River Delta are family type, individual factor, rural factor, migration factor, and location factor. Based on the results of this study, we put forward community-based policy suggestions for citizenization strategy. [ABSTRACT FROM AUTHOR]

With the increase in China's land marketization level, the fundamental role of pricing mechanisms in optimizing the allocation of land resources has received greater attention and has affected foreign direct investment (FDI). This paper analyzes the effects of land marketization level and land prices on FDI using a mediation model based on data on primary land market transactions in 256 cities from 2003 to 2019. The results indicate that the land marketization level, land prices, and FDI are all increasing, with regional heterogeneity. Compared with low-level cities, the land marketization level and land prices in high-level cities have increased the most. Low-level cities have become new hotspots for FDI, whereas high-level cities remain the main destinations for FDI. Both land marketization levels and land prices significantly promote FDI. Land marketization level exerts a weak direct positive effect on FDI in high-level cities but a strong indirect positive effect on FDI in high-level cities through land prices in general. The results of this study enrich the literature on the location decisions of multinational corporations and may serve as a reference for China and other developing countries in developing policies to attract FDI. [ABSTRACT FROM AUTHOR]

This study uses multiple sources of data, including comments on the Internet and the urban transport road network, to analyze the spatial differentiation in the quality of different business environments in the main city area of Dalian. In addition, we used the local Getis-OrdGi* index and the space syntax model as references to optimize the space form of the commercial environment. This study reveals the internal relationship between the road network and quality of the commercial environment based on big data; this result has an innovative and guiding significance for urban commercial development. The study achieved the following results. First, the hotspots of business environment quality features a spatial pattern of "one main and four secondary." Second, the road networks with high global integration are mainly situated in the central city, the main road to the outer city, and the key transport hubs. Third, global integration, local integration, and local choice of the road network have a relatively large impact on the business environment quality. Additionally, the impact of the global choice on the business environment quality is relatively small. Fourth, the correlation coefficient between global choice and the quality of business environments for leisure and entertainment suggest a positive relationship, but negatively correlates with life services and science, education, culture, and health. Finally, the local choice is negatively correlated with the quality of business environments for science, education, culture, and health, whereas it positively correlates with the business environment quality for leisure and entertainment and life services. [ABSTRACT FROM AUTHOR]

Nighttime light (NTL) data have become increasingly practical and are now widely used in studies on urbanization, energy consumption, population estimation, socio-economic evaluation, etc. Based on NTL data and the basic tourism economy (TE) data from 31 provinces of China in 2019, this paper adopted a geographic concentration index, inconsistency index, spatial agglomeration coupling index, global and Local Moran's index and geographical detector to explore the spatial relationship between NTL and TE. The results of the study were as follows. Firstly, there is a high spatial correlation between NTL and TE. Secondly, the concentration degree, as well as the concentrated distribution area of NTL and TE, are very similar, roughly showing a higher concentration in East and South-Central China. Thirdly, NTL and TE show a type of coordinated development in East and North China, and a TE surpassing NTL in Southwest and South-Central China. The spatial agglomeration coupling index is higher in North China, South-Central China and the coastal regions of East China, and relatively lower in Southwest and Northwest China. Furthermore, in the spatial agglomeration distribution of NTL and TE, there is an obvious high–high and low–low agglomeration. Finally, the geographical detector analysis showed that the driving factor of tourism economy level (TEL) also has a great influence on NTL. The spatial distribution of NTL and TE is integrated to reasonably allocate tourism resources for different areas and promote the sustainable development of NTL and TE among regions. [ABSTRACT FROM AUTHOR]

The urban form (e.g., city size, shape, scale, density, etc.) can impact the air quality and public health. However, few studies have been conducted to assess the relationship between the urban form and PM2.5 concentrations on a regional scale and long-term basis in China. In this study, we explored the impact of the urban form on the PM2.5 concentrations in four different regions (i.e., northeast, central, east, western) across China for the years 2000, 2005, 2010, and 2015. Five landscape metrics were classified into three characteristics of the urban form (compactness, shape complexity, and urban expansion) using high-resolution remote-sensing data. With considerations given to regional differences, panel-data models and city-level panel data were used to calculate the impact of the urban form on the PM2.5 concentrations. The results of the study indicate that urban expansion is positively correlated with the PM2.5 concentrations across China, with the only exception being the country's western region, which suggests that urban extension is conducive to increasing the PM2.5 levels in relatively developed regions. Meanwhile, the positive relationship between the irregularity of cities and the PM2.5 concentrations indicates that reducing the urban shape complexity will help to mitigate PM2.5 pollution. Moreover, urban compactness, which mainly refers to the landscape-division-index values, proved to have a negative effect on the PM2.5 concentrations, suggesting that the optimization of urban spatial compactness could reduce PM2.5 levels. The findings of this study are beneficial for a better understanding of the intensity and direction of the effect of the urban form on PM2.5 concentrations. [ABSTRACT FROM AUTHOR]

The intrinsic exothermic reaction of coal with oxygen during low-temperature oxidation is the main heat source responsible for the self-heating and spontaneous combustion of coal. Due to the complexity of low-temperature oxidation of coal with many parallel reactions, it is difficult to directly investigate the heat evolution due to the reaction of coal with oxygen by conventional analytical method. Differential scanning calorimeter (DSC) was introduced in this study to study the intrinsic exothermic reaction of coal with oxygen based on the heat evolution. Using the subtraction analysis method of DSC, the DSC-subtraction curves can be obtained by subtracting the DSC–N2 curves from the DSC-air curves. Experimental results indicate that the DSC-subtraction curve can better reflect the intrinsic exothermic reaction of coal oxidation than a DSC-air curve by eliminating the influence of evaporation of water and thermal decomposition of inherent functional groups. The experiment factors affecting the intrinsic reaction were also investigated with the subtraction method of DSC. In terms of the kinetics characteristics of heat evolution, the intrinsic reaction of coal with oxygen is divided into three stages: slow oxidation stage, advanced oxidation stage, and rapid oxidation stage. The activation energies and pre-exponent factors at each of the stages were also calculated by oxidative pyrolysis kinetics. The subtraction method applied in this study is a quite promising method to determine the susceptibility of coal to self-heating and spontaneous combustion. [ABSTRACT FROM AUTHOR]

A good understanding of the intrinsic relationship between heat evolution and mass change induced by coal–oxygen oxidation reaction is critical for accurately predicting the behaviour of spontaneous combustion. In this study, thermal subtraction method and six sets of characteristic temperatures were introduced to explore the intrinsic reaction between coal and oxygen which provides the main heat source responsible for coal self-heating. The heat evolution and mass change during coal spontaneous combustion were measured in real time using a sensitive differential scanning calorimeter (DSC) and a thermogravimetric analyzer (TG), respectively. The DSC and TG subtraction curves obtained from subtracting the results of nitrogen atmosphere from those of air atmosphere can reveal the heat change and mass change due only to the reaction between coal and oxygen. The term of q/m defined as the amount of heat release by the change of per unit of coal mass was introduced to study the intrinsic relationship between heat evolution and mass change during coal spontaneous combustion. The q/m values of the three coals show different evolution trends as coal temperature increases and are related to the mechanism of coal spontaneous combustion. The kinetics analysis of this intrinsic relationship was also carried out based on experimental data. Moreover, q/m can be used in the evaluation of spontaneous combustion propensity with respect to different coal types. [ABSTRACT FROM AUTHOR]

Agriculture Powers Urbanization. How and when agriculture influences urbanization in underdeveloped regions remain poorly understood from an agricultural contribution perspective, specifically the food contribution (FDC), raw materials contribution (MLC), labor contribution (LRC), and market contribution (MTC). This study investigated this issue in the context of Tibet. A Granger causality test (GCT), the impulse response function (IRF), and variance decomposition (VD) were used. The GCT results demonstrated that agricultural contribution factors (ACFs), Granger-cause urbanization, and the IRF and VD results demonstrated that the influences of ACFs on urbanization were various and asynchronous. Both MTC and LRC quickly and positively respond to urbanization; however, LRC currently influences urbanization, whereas MTC influences urbanization currently and in the future. Both MLC and FDC negatively and slowly respond to urbanization; however, MLC currently influences urbanization, whereas FDC will influence urbanization in the future. This study's findings depict changing trajectories of the role of ACFs in urbanization, elucidating urban–rural transformation. [ABSTRACT FROM AUTHOR]

It is imperative to have an in-depth understanding of CO overrun at the air return corner not only for pre-warning concentrations of safety and spontaneous combustion but also for providing scientific guidance for the CO management. In this study, CO sources and early-warning concentration of spontaneous combustion at the air return corner in fully mechanized mining faces were investigated. Through field measurements, the main sources responsible for CO occurring at the air return corner of the fully mechanized mining face were determined and analyzed, and the basic parameters of mining and ventilation conditions were obtained from the field trials. In the laboratory, an enclosed reactor was introduced and a series of simulated experiments of coal oxidation was carried out to explore coal oxidation at ambient temperature; simultaneously, the temperature-programmed oxidation experiments were also carried out to determine the critical temperature of coal spontaneous combustion and to obtain the rate of CO production at a critical temperature. According to the analysis of the CO source and the production mechanism in the working face as well as both the distribution and migration rules of CO concentration in goaf and working face, a mathematical prediction model of the CO concentration at the air return corner of the working face under normal operation was established. And then the prediction of CO safety and spontaneous combustion early-warning concentrations were calculated based on the CO production rates of coal oxidation under ambient temperature and at a critical temperature. Moreover, a detailed operational process for the practical applications of the mathematical prediction model to the return corner of other fully mechanized mining faces was also proposed. [ABSTRACT FROM AUTHOR]

Urban agglomerations are fundamental regional units of development and attract large-scale migrant population. Previous studies have only focused on migrant population distribution in major urban agglomerations. Therefore, this study analysed the spatiotemporal characteristics of migrant population distribution in China during 2000–2010 at city level from the perspective of urban agglomerations. The results indicate that urban agglomerations were accumulation areas of migrant population. Numerous people have migrated into 19 urban agglomerations, which has enlarged regional differences in migrant population distribution. The interprovincial migrant population dominated within urban agglomerations, whereas the intraprovincial migrant population dominated outside urban agglomerations. In the future, intraprovincial migration will become the dominant migration mode. The evolution of migrant population distribution pattern in urban agglomerations agrees with classic theories of unbalanced regional development. The determinants of migration in different regions were compared. Results revealed that economic and government driving forces jointly influenced migration; however, economic forces exceeded government forces. Economic forces were more influential within urban agglomerations, whereas government forces played more important roles outside urban agglomerations. Increased income and job opportunities were the core attractions of urban agglomerations. Moreover, with an increase in the urban agglomeration development level, the influence of economic forces increased, whereas that of government forces decreased. The findings provide a deeper understanding of migrant population distribution in China, which will benefit population management across various regions. [ABSTRACT FROM AUTHOR]

The Chinese government has provided various forms of assistance to the Tibet Autonomous Region and has substantially improved their facilities, which has had a positive influence on the development of tourism in Tibet. The present study investigated how assistance to Tibet (AT) coordinates with tourism development (TD) by exploring the patterns and influencing factors of AT and TD using statistical data from 74 prefectural units from 1991 to 2015. The findings led to several conclusions: (1) AT displayed strong and constant coupling interactions with TD, and the coupling coordination degree increased from moderately unbalanced development (MUD) to barely balanced development (BBD). However, the coupling coordination degree remains low (MUD) in most prefectural units; (2) in 2015, the degree of coupling coordination displayed a "core-periphery" spatial pattern (i.e., low in center and high in the periphery), which highly coincides with the patterns of AT (x) and TD (y), and should thus be improved further; and (3) both AT factors and TD factors have significant effects on the spatial differentiation of coupling coordination degree but not on the coupling degree. This study expands research on coupling coordination and AT and provides scientific guidance for further coordinating AT and TD. [ABSTRACT FROM AUTHOR]

Appropriate spatial distribution of primary and secondary schools for relocated children of migrant workers (RCMW) is extremely valuable to ensure the fair education of special groups and improve the quality of their education. This study used concentration analysis, kernel density estimation (KDE), and coefficient of variation (CV) to measure the spatial agglomeration of these children and their primary and secondary schools in the districts and counties of Liaoning Province from 2008 to 2017 based on government surveys. The results showed that the number of RCMW children in primary and secondary schools increased during the research period and the growth rate of children in primary schools was higher than that of children in junior high schools. The number of primary and secondary schools has changed very little, while the number of secondary schools has dropped sharply. The spatial distribution of RCMW and that of their primary and secondary schools were characterized by a "dual-core" distribution and a three-level (county, city, and provincial capital) gradient aggregation. In addition, kernel density evolved from a balanced distribution to polar nucleus-shaped, clustered, and discretized distributions, respectively. Specifically, the "large" and "super-large" schools were mainly concentrated in cities, showing a clustered pattern. "Medium-sized" and "small" schools were mainly distributed in counties, presenting a discretized pattern. In addition, when the CV of the number of RCMW increased, the imbalanced distribution of schools became more significant. Furthermore, the spatial differentiation of primary and secondary schools for RCMW appeared to be affected by economic development, population size, and related policies in the region. [ABSTRACT FROM AUTHOR]

Many studies have used housing prices on the Internet real estate information platforms as data sources, but platforms differ in the nature and quality of the data they release. However, few studies have analysed these differences or their effect on research. In this study, second-hand neighbourhood housing prices and information on five online real estate information platforms in Guangzhou, China, were comparatively analysed and the performance of neighbourhoods' raw information from four for-profit online real estate information platforms was evaluated by applying the same housing price model. The comparison results show that the official second-hand residential housing prices at city and district level are generally lower than those issued on four for-profit real estate websites. The same second-hand neighbourhood housing prices are similar across each of the four for-profit real estate websites due to cross-referencing among real estate websites. The differences of housing prices in the central city area are significantly fewer than those in the periphery. The variation of each neighbourhood's housing prices on each website decreases gradually from the city centre to the periphery, but the relative variation stays stable. The results of the four hedonic models have some inconsistencies with other studies' findings, demonstrating that errors exist in raw information on neighbourhoods taken from Internet platforms. These results remind researchers to choose housing price data sources cautiously and that raw information on neighbourhoods from Internet platforms should be appropriately cleaned. [ABSTRACT FROM AUTHOR]

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Summary: Spontaneous combustion of coal is one of the main disasters affecting safe production in mines. A sodium carboxymethyl cellulose/aluminium citrate gel for prevention and extinguishing of mine fires was prepared. Based on a temperature‐controlled experiment, the authors studied the influences of the gel on indicator gases generated in the spontaneous combustion of coal, crossing point temperature, and activation energy. The results showed that the crossing point temperature of coal samples treated by the gel increased by more than 13.9°C and the activation energy rose by 7.17 to 16.34%. Moreover, the indicator gases, such as CO and C2H4 generated in the oxidation, decreased significantly. After treatment with the gel, the weight loss rate of the coal samples was reduced, and less energy was released. By using the self‐developed test platform (coal capacity of 2 m3), the spontaneous combustion of coal on the roof of a roadway was simulated, and the carboxymethyl cellulose/aluminium citrate gel was used for fire extinguishing. After injecting the gel, the temperature in the furnace rapidly decreased, and the concentration of O2 remained at less than 3%, without showing any after‐combustion effects. [ABSTRACT FROM AUTHOR]

Many studies have qualitatively explained that information and communication technology (ICT) has loosened the restrictions of distance and space on retailers' sales. Few empirical studies, however, have explored the impact of shipping distance on online retailers' sales. This study examined the Maiyang (M-Y) store on Tmall in China as a case study to investigate the relationship between shipping distance and sales. The results showed that sales volume in 2014 at the county level did not strictly obey the distance decay law. The shipped distance of high-priced commodities may not be much longer than that of low-priced commodities. Within the scope of investigation, the relationships between income, cost, and net profit curves do not follow central place theory. Goods have neither thresholds nor ranges. The key factor in the spatial discrepancy of sales is the size of market. The impact of shipping distance on sales is not as strong as that of traditional retailers in Information Era. [ABSTRACT FROM AUTHOR]

In order to manage water resources, a software sensor model was designed to estimate water quality using a hybrid fuzzy neural network (FNN) in Guangzhou section of Pearl River, China. The software sensor system was composed of data storage module, fuzzy decision-making module, neural network module and fuzzy reasoning generator module. Fuzzy subtractive clustering was employed to capture the character of model, and optimize network architecture for enhancing network performance. The results indicate that, on basis of available on-line measured variables, the software sensor model can accurately predict water quality according to the relationship between chemical oxygen demand (COD) and dissolved oxygen (DO), pH and NH4+–N. Owing to its ability in recognizing time series patterns and non-linear characteristics, the software sensor-based FNN is obviously superior to the traditional neural network model, and its R (correlation coefficient), MAPE (mean absolute percentage error) and RMSE (root mean square error) are 0.8931, 10.9051 and 0.4634, respectively. [ABSTRACT FROM AUTHOR]

In this work, we reported a valid method to sort large-diameter semiconducting single-walled carbon nanotubes (sc-SWCNTs) from commercial arc discharge SWCNTs by different conjugated organic compounds. Seven kinds of high-purity sc SWCNT inks were achieved. As-prepared sc-SWCNT inks were directly used to fabricate printed SWCNT TFT arrays and backplane circuits on rigid substrates. It was found that printed SWCNT TFT devices exhibited high-performance with low operating voltage (±2 V), small subthreshold swing (ss), small hysteresis, high mobility (more than 20 cm2 /Vs) and high on/off ratios (up to 106 ). Printed 2T-1C driving circuit exhibited high on/off ratio up to 105 and high output current up to 8×10-5 μ A at Vdata, Vscan and Vdd of -2 V, respectively. Furthermore, 15×15 OLED pixel arrays were switched on with printed SWCNT driving circuits on glass substrates, suggesting printed SWCNT driving circuits have the potential as backplanes for active matrix OLED applications. [ABSTRACT FROM AUTHOR]

The middle class in metropolitan Chinese cities has become an important social group. With the rapid development of urbanization and constant advancement of suburbanization, the middle class has increasingly come to influence city traffic. Research into middle-class commuting activities thus has practical significance for improving traffic congestion and reducing the commuting burden in metropolitan cities. Based on a dataset formed by 816 completed surveys, this paper analyzes the commuting mode, time and distance of middle-class residents in Guangzhou City using the descriptive statistical method. The results indicate that private cars are the main commuting mode, followed by public transport. Meanwhile, middle-class residents mainly undertake medium-short time and medium- short distance commuting. The study subsequently uses multilevel logistic regression and multiple linear regression models to analyze the factors that influence commuting mode choice, time and distance. The gender, age, number of family cars, housing source and jobs-housing balance are the most important factors influencing commuting mode choice; housing, population density, jobs-housing balance and commuting mode significantly affect commuting time; and transport accessibility, jobs-housing balance and commuting mode are the notable factors affecting commuting distance. Finally, this paper analyzes what is affecting the commuting activities of middle-class residents and determines the differences in commuting activity characteristics and influence factors between middle-class and ordinary residents. Policy suggestions to improve urban planning and urban management are also proposed. [ABSTRACT FROM AUTHOR]

A thorough study of environmentally friendly hydroxylation of aryl halides is presented. The best protocol consists of hydroxylation of different aryl bromides and electron-deficient aryl chlorides by water solution of tetrabutylammonium hydroxide catalyzed by Cu2O/4,7-dihydroxy-1,10-phenanthroline. Various phenol derivatives can be obtained in excellent selectivity and great functional group tolerance. This methodology also provides a direct pathway for the formation of alkyl aryl ethers and benzofuran derivatives in a one-pot tandem reaction. [ABSTRACT FROM AUTHOR]

Two flexible click-based porous organic polymers (CPP-F1 and CPP-F2) have been readily synthesized. SEM images show CPP-F1 is a 3D network, while CPP-F2 exhibits a granular morphology. Pd(OAc) can be easily incorporated into CPP-F1 and CPP-F2 to form Pd@CPP-F1 and Pd@CPP-F2, respectively. The interactions between the polymers and palladium are confirmed by solid-state C NMR, IR and XPS. Palladium nanoparticles (NPs) are formed after hydrogenation of olefins and nitrobenzene. Palladium NPs in CPP-F1 are well dispersed on the external surface of the polymer, while palladium NPs in CPP-F2 are located in the interior pores and on the external surface. In comparison with NPs in CPP-F1, the dual distribution of palladium NPs in CPP-F2 results in higher selectivity in the hydrogenation of 1,3-cyclohexadiene to cyclohexane. The catalytic systems can be recycled several times without obvious loss of catalytic activity or agglomeration of palladium NPs. Hot filtration, mercury drop tests and ICP analyses suggest that the catalytic systems proceed via a heterogeneous pathway. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A series of 1,10-phenanthroline derivatives were used as supporting ligands for copper-catalyzed Ullmann reaction in neat water. The catalytic system based on 4,7-dihydroxy-1,10-phenanthroline has demonstrated the promising catalytic performances for aryl bromides. The catalytic system was applicable to a wide scope of substrates, high catalytic activity and selectivity were observed for the reactions of electron-deficient, electron-rich, and heterocyclic aryl bromides with imidazoles containing different steric hindrance. The superior promoting effect of 4,7-dihydroxy-1,10-phenanthroline is attributed to its water solubility under the basic conditions. [ABSTRACT FROM AUTHOR]

Objectives: Few studies have examined the impacts of structural differences in the urban–rural dichotomy under the new household registration policy on migration and settlement behavior. Nevertheless, the rationale for the settlement policy of local governments should be further elucidated and improved. This study aims to analyze the household registration, land property rights, and differences in migrants' settlement intentions. Methods: This study used migration survey data from the Pearl River Delta and probit regression to fill this gap in the literature. Findings: Because of the long-term effects of the household registration system and their socioeconomic differences, urban-urban migrants and rural–urban migrants differed in their settlement intentions. Furthermore, the new points-based household registration system affected migrants' settlement intentions. Relative to the rural–urban migrants, urban–urban migrants more easily met the settlement requirements under the points-based system, and they tended to settle in their current cities. By contrast, migrants with farmland in their hometowns tended to settle there. The findings underscore the relevance of adopting perspectives that consider the urban–rural dichotomy and related structural differences to understand migrants' settlement intentions in China. [ABSTRACT FROM AUTHOR]

Polyurethane elastomer (PUE) was firstly applied to mining coal roadway as air-leak sealant. It is very important for air-leak sealants to possess the super mechanical properties and good flame retardant performance when applied to the coal-rock mass with cracks. The reinforced and toughened PUE nanocomposites were obtained by adding surface modified TiO2 and SiO2 nanoparticles. The modified PUE was characterized in terms of morphology, structure, and thermal stability by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), infrared spectroscopy (IR), and thermogravimetric analysis (TGA). Its flame-retardant performance and mechanical properties were also tested. The results showed that the surface modified nanoparticles were uniformly dispersed in the PUE matrix and enhanced its thermal stability and flame retardant performance. The dual effects of uniform dispersion of nanoparticles and hydrogen bonding between nanoparticles and PUE improved the mechanical properties of the composites. The PUE modified by nanoparticles was successfully applied to coal mines and showed great air-leak sealing effect. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

A water-soluble ionic palladium(II) nitrogen-containing chelating complex, [palladium(II) 1-(4- N, N′, N′′-trimethylbutylammonium)-4-(2-pyridyl)-1 H-1,2,3-triazole dichloride] chloride ( 3), was prepared through the click reaction of 1-chloro-4-bromobutane, sodium azide, and 2-ethynylpyridine, followed by the quarternization of Me3N and subsequent reaction with [Pd(cod)Cl2] (cod=1,5-cyclooctadiene). The catalytic performances of complex 3 were preliminarily evaluated through Suzuki-Miyaura and Hiyama cross-coupling reactions of aryl bromides; excellent catalytic activity in water was observed. TEM analysis revealed that small palladium nanoparticles (NPs) with a narrow size distribution were formed after the catalytic reaction. The NPs were stabilized by the synergetic effect of coordination and electrostatic interactions from the ionic, bidentate, nitrogen-containing ligand; no palladium black was detected after the aqueous solution of palladium NPs was stored in air for months. The use of 3 as a precursor in the formation of palladium NPs was further explored by using NaBH4 and hydrogen as reductive reagents. The resulting NPs displayed different sizes, surface properties, and catalytic performances in the Suzuki-Miyaura cross-coupling reaction in water. [ABSTRACT FROM AUTHOR]

A hydrophobic palladium complex of the chelating N-heterocyclic dicarbene (NHDC) (3) was synthesized through in situdeprotonation of a bisimidazolium salt (2) by Pd(OAc)2in DMSO, subsequent basic hydrolysis and acidification resulted in the formation of four NHDC palladium complexes bearing carboxylic functional groups (4–7). Complexes 4–7are air-stable, pH-responsive and water-soluble under basic conditions due to deprotonation of the carboxylic groups. The catalytic activities of the hydrophilic catalytic systems from 4–7were preliminarily evaluated using the Suzuki–Miyaura cross-coupling reaction in pure water, high catalytic activity and chemical selectivity were observed in comparison with their hydrophobic analogue from 3. Either the catalytic aqueous solution or the pH-responsive catalysts were easily separated and could be recycled at least four times. TEM analysis revealed that Pd(0) nanoparticles were formed after the catalytic reaction. [ABSTRACT FROM AUTHOR]

An ammonium-functionalized water-soluble bidentate nitrogen-containing ligand (3) and its palladium chelating complex (4) have been easily prepared from the commercial available starting materials in high overall yields. The charge distributions and molecular orbital analyses of 3, 4and non-ionic hydrophobic analogue (2a) based on the optimized structures were implemented. The crystal structure of 4has been established by single-crystal X-ray diffraction. The water-soluble palladium complex was a much more effective catalyst than 2ain palladium-catalyzed Suzuki–Miyaura cross-coupling reaction in air and pure water. High catalytic activity of aryl chlorides and aryl bromides was observed. The mercury drop test, poison experiments and TEM analysis of the catalytic solution showed Pd(0) were involved in catalysis. The palladium nanoparticles of 3.0 ± 0.6 nm were formed after the catalytic reaction, they were stabilized by synergetic effect of coordination and electrostatic interactions from the ammonium-functionalized chelating ligand. No precipitate was observed when the aqueous nanoparticles were stored in air for months. [ABSTRACT FROM AUTHOR]

A hydrophobic palladium complex of the chelating N-heterocyclic dicarbene (NHDC) (3) was synthesized through in situ deprotonation of a bisimidazolium salt (2) by Pd(OAc)2 in DMSO, subsequent basic hydrolysis and acidification resulted in the formation of four NHDC palladium complexes bearing carboxylic functional groups (4–7). Complexes 4–7 are air-stable, pH-responsive and water-soluble under basic conditions due to deprotonation of the carboxylic groups. The catalytic activities of the hydrophilic catalytic systems from 4–7 were preliminarily evaluated using the Suzuki–Miyaura cross-coupling reaction in pure water, high catalytic activity and chemical selectivity were observed in comparison with their hydrophobic analogue from 3. Either the catalytic aqueous solution or the pH-responsive catalysts were easily separated and could be recycled at least four times. TEM analysis revealed that Pd(0) nanoparticles were formed after the catalytic reaction. [ABSTRACT FROM AUTHOR]

An ammonium-functionalized water-soluble bidentate nitrogen-containing ligand (3) and its palladium chelating complex (4) have been easily prepared from the commercial available starting materials in high overall yields. The charge distributions and molecular orbital analyses of 3, 4 and non-ionic hydrophobic analogue (2a) based on the optimized structures were implemented. The crystal structure of 4 has been established by single-crystal X-ray diffraction. The water-soluble palladium complex was a much more effective catalyst than 2a in palladium-catalyzed Suzuki–Miyaura cross-coupling reaction in air and pure water. High catalytic activity of aryl chlorides and aryl bromides was observed. The mercury drop test, poison experiments and TEM analysis of the catalytic solution showed Pd(0) were involved in catalysis. The palladium nanoparticles of 3.0 ± 0.6 nm were formed after the catalytic reaction, they were stabilized by synergetic effect of coordination and electrostatic interactions from the ammonium-functionalized chelating ligand. No precipitate was observed when the aqueous nanoparticles were stored in air for months. [ABSTRACT FROM AUTHOR]

This study quantitatively investigated the relationship between climate change (proxied by CO2 emissions), air pollution (proxied by PM2.5 concentration levels and PM10 and SO2 emissions), and tourism flows (proxied by inbound and domestic tourist arrivals) using panel data for 30 Chinese provinces from 2010 to 2017. The results demonstrate a long-term equilibrium relationship between CO2 emissions, air pollution variables, and tourism flows (including the number of inbound and domestic tourists). The panel data model results show that CO2 emissions have an opposite effect on inbound and domestic tourist arrivals, while domestic and inbound tourists positively affect CO2 emissions. PM2.5 level and PM10 and SO2 emissions all have a negative effect on the number of tourists. There is bidirectional causality between CO2 emissions and domestic tourist arrivals, which means CO2 emissions and domestic tourist arrivals have a two-way effect. A one-way causality running from PM2.5 to inbound tourist arrivals and SO2 emissions to domestic tourist arrivals was found. Moreover, we also found bidirectional causality between PM10 and inbound tourist arrivals and PM10 and domestic tourist arrivals. Variance decomposition function results suggest that PM10 and SO2 emissions have stronger effects on inbound tourist arrivals in the long term, while CO2 emissions and PM10 have stronger power in explaining innovations in domestic tourist arrivals. The movements in the domestic tourist arrivals do significantly affect CO2 emissions in the long run. The study provides theoretical implications and guidance for achieving a healthy and sustainable tourism industry. [ABSTRACT FROM AUTHOR]

X-5 resin, with higher adsorption and easier desorption of naringin, was selected from five kinds of macroporous resins through static adsorption and desorption experiments. Effects of concentration, pH value, and flow rate of naringin extract on the adsorption of naringin by X-5 resin were studied. Meanwhile, the effect of these factors on the desorption of naringin from X-5 resin was also investigated. The experimental results show that the adsorption isotherm of naringin by X-5 resin can be described by the Langmuir isotherm equation. The static maximum adsorption capacity of naringin is 32.6 mg/g with naringin concentration at 2.7 g/L, while the dynamic adsorption capacity of naringin is 23.8 mg/g with naringin extract flow rate at two times that of resin volume per hour. The optimal eluant is 60% (v/v) ethanol-water with pH value of 10. The desorption ratio will rise to more than 85% when the flow rate of this optimal eluant is one to two times that of resin volume per hour. [ABSTRACT FROM AUTHOR]

Based on chemical thermodynamic theory, racemic ofloxacin is separated in chiral systems by hollow fiber liquid-supported membrane technology combining with countercurrently fractional extraction. The two chiral solutions containing L-dibenzoyltartaric acid and D-dibenzoylta-rtaric acid in 1-octanol, flow through the lumen side and the shell side of fibers, respectively. The solution which flows through the lumen side of fibers also contains racemic ofloxacin. The wall of hollow fibers is filled with an aqueous of 0.1 mol/L Na2HPO4/H3PO4 buffer solution of pH = 6.86 containing 2 mmol/L of cetyltrimethyl ammonium bromide for 48 h. The fairly polar ofloxacin can cross the membrane back and forth, but dibenzoyltartaric acids cannot cross it. Fractional chiral extraction theory, mass transfer performance of hollow fiber membrane and enantioselectivity are investigated. Mathematical model of R/S = 0.96e0.03NTU for racemic ofloxacin separation by hollow fiber extraction, is established. The optical purity for ofloxacin enantiomers is up to 90% when 11 hollow fiber membrane modules of 22 cm in length in series are used. [ABSTRACT FROM AUTHOR]

The rapid development of the urban city has led to great changes in the urban spatial structure. Thus, analyses of polycentric urban spatial structures are important for understanding these kinds of structures. In order to accurately evaluate the polycentric spatial structure of urban agglomerations and judge the differences between the actual development situation and overall planning of urban agglomerations, this study proposes a new method to identify the polycentric spatial structure of urban agglomerations in the Pearl River Delta based on the fusion of nighttime light (NTL) data, point of interest (POI) data, and Tencent migration data (TMG). In the first step, the NTL, POI, and TMG data are fused via wavelet transform; in the second step, Anselin local Moran's I (LMI) and geographically weighted regression (GWR) were used to identify the main centers and subcenters, respectively. In the third step, the accuracy of the results of this study was further verified and discussed in the context of overall planning. The results show that the accuracy of urban polycenter identification via LMI and GWR after data fusion was 92.84%, and the Kappa value was 0.8971, which was higher than the results of polycenter identification via the traditional relative threshold. After comparing the identification results with the overall planning, firstly, we see that the fusion of multi-source big data can help to accurately evaluate the polycentric spatial structure within the urban agglomeration. Secondly, the fusion of dynamic data and static data can help identify the polycentric spatial structure of urban space more accurately. Therefore, this study can provide a new design for urban polycentric spatial structures, and further provide a reliable reference for the spatial optimization of urban agglomeration and the formulation of regional spatial development policies. [ABSTRACT FROM AUTHOR]