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To overcome the shortcoming of the Fuzzy C-means algorithm (FCM)—that it is easy to fall into local optima due to the dependence of sub-spatial clustering on initialization—a Multi-Strategy Tuna Swarm Optimization-Fuzzy C-means (MSTSO-FCM) algorithm is proposed. Firstly, a chaotic local search strategy and an offset distribution estimation strategy algorithm are proposed to improve the performance, enhance the population diversity of the Tuna Swarm Optimization (TSO) algorithm, and avoid falling into local optima. Secondly, the search and development characteristics of the MSTSO algorithm are introduced into the fuzzy matrix of Fuzzy C-means (FCM), which overcomes the defects of poor global searchability and sensitive initialization. Not only has the searchability of the Multi-Strategy Tuna Swarm Optimization algorithm been employed, but the fuzzy mathematical ideas of FCM have been retained, to improve the clustering accuracy, stability, and accuracy of the FCM algorithm. Finally, two sets of artificial datasets and multiple sets of the University of California Irvine (UCI) datasets are used to do the testing, and four indicators are introduced for evaluation. The results show that the MSTSO-FCM algorithm has better convergence speed than the Tuna Swarm Optimization Fuzzy C-means (TSO-FCM) algorithm, and its accuracies in the heart, liver, and iris datasets are 89.46%, 63.58%, 98.67%, respectively, which is an outstanding improvement. [ABSTRACT FROM AUTHOR]

Green finance is an effective policy instrument in mitigating climate change, but to date little is known about its impact on carbon dioxide (CO 2) emissions. This study extends the literature on the relationship between green finance and CO 2 emissions while taking trade openness and economic development into consideration to comprehensively explore the conservation/feedback hypothesis using the Autoregressive-Distributed Lag–Error Correction Model (ARDL–ECM) on data collected from 2000 to 2019. By constructing a green finance index comprising green credit, green securities, green insurance, and green investment, results include the following. (1) Support was found for the conservation hypothesis running from green finance, trade openness, and economic development to emissions per capita; the conservation hypothesis also was supported for the unidirectional relationship running from trade openness and economic development to green finance. (2) Green finance is found to be significantly and negatively related to emissions per capita in both the short and long term. (3) Trade openness shows a positive effect on emissions per capita. Robustness tests are provided. This study deepens policy implications of green finance in the post-pandemic era and highlights the moderating role of renewable energy in the green finance impact on carbon mitigation. • This study constructs a green finance index for China. • The autoregressive distributed lag–error correction model is employed. • Green finance contributes to carbon mitigation in both the short and long run. • CO 2 emissions are Granger result of green finance, trade openness and economic growth. • Trade openness and economic growth are Granger causes of each other. [ABSTRACT FROM AUTHOR]

As Internet usage reshapes our societies, digital inequalities have increased over the past few decades. During the COVID-19 pandemic, many countries accelerated their digital transformation processes, and it is widely believed the COVID-19 pandemic has deepened existing inequalities in the digital realm. Yet, few studies have empirically examined whether digital inequalities in the labor market increased during the pandemic. This analysis studies how the COVID-19 pandemic affected Chinese workers' Internet usage and how this influence varied across socioeconomic groups. By using the ordered probit model and leveraging the most recent data from the China Family Panel Studies and the Johns Hopkins Coronavirus Resource Center, we find that the pandemic significantly increased the overall level of Internet usage in the country, and the mediating effects of the perceived importance of the Internet and access to the Internet are confirmed. As Internet usage increased, digital inequalities in China's labor market deepened, especially among young and wealthy workers with high social status in urban areas, while older and poorer workers in rural areas benefited less from this new 'digital wave.' Moreover, during the pandemic, Internet usage increased among employees working in state-owned enterprises (SOEs), which suggests a growing digital inequality gap between SOEs and other sectors. Following a series of robustness tests, our research findings remain valid. We propose a policy redesign that embodies a comprehensive long-term vision and guarantees raising the levels of Internet usage for socially and economically disadvantaged groups in China. • COVID-19 pandemic in China causes a significant increase of Internet usage rate; • Mediating roles of perceived importance of Internet and access to Internet are confirmed; • Digital inequalities deepen as Internet usage increased for certain socioeconomic groups; • The young and wealthy citizens with a high social status are benefitted from such digitalization. • Internet usage rate is significantly increased for SOE employees than other sectors. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the existence of pollution haven hypothesis (PHH) and test the casual relationship between inward foreign direct investment (FDI) and environmental pollutions, as well as other potential influencing factors of environmental performance. To this end, a panel vector error correction model (VECM) and panel co-integration test is conducted for two country groups - the BRICS (i.e., Brazil, Russia, India, China, and South Africa) and the MINT (i.e., Mexico, Indonesia, Nigeria, and Turkey) - during 1982–2014. Empirical results illustrate a bidirectional and positive causality between FDI inflows and GDP per capita for both groups, implying a virtuous circle of FDI-growth nexus. More importantly, both the BRICS and MINT countries illustrate bidirectional and negative causality between FDI inflows and environmental pressures (i.e., per capita energy consumption for BRICS and per capita carbon emissions for MINT). Such findings indicate the pollution haven hypothesis does not stand in this case. In addition, it is also found that the opening degree of trade can be promoted by FDI inflows, which has rarely been deeply analyzed in prior studies. Concluding remarks and policy suggestions are proposed in the last section. Image 1 • Vector error correction model are employed in this study. • A comparative analysis of BRICS and MINT countries. • Results refute the pollution haven hypothesis. • A virtuous circle exist between FDI and economic growth. • Trade openness can be promoted by FDI inflows. [ABSTRACT FROM AUTHOR]

Abstract A comprehensive understanding of the relationships between environmental regulations and green growth of economy is essential for policy design and decision-making. This paper combines hybrid measure with Global Malmquist Luenberger index to estimate national green growth level. A panel threshold regression technique is then employed to observe the non-linear impacts of both the formal and informal environmental regulations on green growth in Group 20 countries during 2001–2015. Results from empirical tests reveal that, for the formal environmental regulations represented by Environmental Policy Stringency (EPS), the market-based EPS is only significant at high-level phase while this is not the case in the low-level counterpart; non-market based EPS witnessed significant signs across the three phases, but in varied coefficients and significance levels. By comparison, the informal environmental regulations represented by environmental-related technologies and education levels show positive and significant impact on green growth, except for the case when countries have higher level of technologies. In addition, income per capita and gross Research & Development (R&D) expenditures present significant positive impacts on the dependent while share of service sector to the economy and investment on transport infrastructure witnessed negative effects across the models. Policy implications are proposed thereafter, although both the formal and informal environmental regulations are important to promote green growth, but they show different impacts at different phases. Graphical abstract Unlabelled Image Highlights • A global Malmquist Luenberger index has been employed to measure green growth. • Non-linear regulation-growth nexus has been examined by panel threshold model. • Environmental Policy Stringency show significant positive effects on green growth. • Education exerts larger impact on green growth than environmental-related technologies. [ABSTRACT FROM AUTHOR]

Abstract Particles with a diameter of <2.5 μm (PM 2.5) have serious adverse-effects on human health, which have caused widespread public concern in recent decades. Currently, most of the existing research on PM 2.5 have used linear regression analysis; very few studies on the subject have been conducted using non-linear models. This study adopts a panel threshold model, which is seldom used in environmental studies, to examine the non-linear effects of environmental regulation and economic growth on PM 2.5 in 30 OECD countries, and we also explore the key driving socio-economic factors for PM 2.5 emissions. The results of our analysis show that, along with an increase in environmental policy stringency, PM 2.5 emissions first rise and then show no significant correlations, and thus a reduction in emissions can be expected if current trends continue. As for GDP per capita, significant and negative correlations are found across the three phases divided by the panel threshold model, indicating a promoting effect for PM 2.5 mitigation. In addition, public expenditure on the air sector correlated positively with PM 2.5 concentrations, expanding the share of service economy reward to reduce air pollution, and urban population ratio exhibits an inverted U-shaped pattern. Future studies may shed more light on the regulation-PM 2.5 nexus, and more studies are needed to confirm the existence of bi-directional correlations between economic development and air pollution. Graphical abstract Unlabelled Image Highlights • Environmental regulation show different impacts on PM 2.5 at high-, mid- and low-level phases; • GDP per capita is negatively correlated with PM 2.5 at 1% level; • Expansion of service industry reduces pollution; • An inverted U-shaped relationship exist between urbanization and pollution. [ABSTRACT FROM AUTHOR]

Dematerialization at the national level occurs almost exclusively during periods of economic recession or low growth. While recession is not a sustainable strategy to curb environmental impact, such periods may offer important insights on the possibilities of reducing material use. Economic recession research has focused on the interactions between macroeconomic and financial variables with little systematic research dedicated to uncovering how resource use develops during periods of recession. Using a dynamic panel model, we investigate whether and to what extent material use in a sample of 150 economies between 1970 and 2010 was affected by recession and low growth. Recession occurred most frequently and in more than two thirds of all countries during the 1980s and the 1990s. In the 2000s, more than half of the recessions occurred during the financial crisis of 2008. Periods of recession were significantly and negatively correlated with material use - they tended to coincide with dematerialization. Material use decreased in recession years, but the significant correlations with growth in material use became weaker as growth rates increased. Construction minerals and metals, used to build stocks of manufactured capital, reacted more strongly to economic fluctuations than the throughput-dominated flows of biomass and fossil fuels. We conclude that the systematic link between recession and dematerialization can become policy-relevant if the mechanisms causing reductions in material use during these periods are identified. [ABSTRACT FROM AUTHOR]

Conventional wisdom has it that less working time is good for mitigating environmental pressure. Only a few studies have documented contradictory evidence. In this paper, we use panel threshold model, which is arguably the first of its kind in environmental analysis, to further document nonlinear relationships between working time and environmental pressure in EU-15 countries between 1970 and 2010. We find that the sign of this relationship shifts from positive to negative, as the working hours per worker decreases; France, Denmark, Germany, and the Netherlands experienced more environmental pressure with shorter working week. To the backdrop of reduced working time during our research period, our paper sheds new light on the traditional view of “the less, the better,” as curtailing working time beyond certain thresholds may inadvertently incur exacerbation of environmental pressure. [ABSTRACT FROM AUTHOR]

Previous studies have considered the effect of financial development on carbon emissions; however, few studies have explored the role of green finance in carbon mitigation. To bridge this gap, the current study constructs a green finance development index based on four indicators: green credit, green securities, green insurance, and green investment. A vector error correction model is used to analyze relationships between the development level of green finance, non-fossil energy consumption, and carbon intensity using data from 2000 to 2018. We find that China's green finance industry developed rapidly, and improvements in the green finance development index, as well as the increasing use of non-fossil energy, contributed to a reduction in carbon intensity. Simultaneously, an increase in carbon intensity inhibited the expansion of non-fossil energy use, impeded the investment flow to green projects, and ultimately led to a deterioration of green finance development. In addition, non-fossil energy consumption in China was primarily influenced by green finance and carbon intensity, with clear policy-driven effects. However, the impacts of green finance policies continually fell short and lacked continuity. This study proposes ways in which to improve the effect of green finance policy implementation, expand the consumption of non-fossil energy, and develop a carbon trading market. • The green finance–new energy use–carbon intensity nexus is explored for China. • A vector error correction model is employed. • A green finance development index is constructed based on four green indicators. • Green finance and new energy use are found to reduce carbon intensity. • Carbon intensity increases are found to inhibit green finance and new energy use. [ABSTRACT FROM AUTHOR]

Most previous studies on comprehensive urban carrying capacity (UCC) have estimated UCC levels and comparatively analyzed the heterogeneity of the sample cities. Very few researchers have focused on the interaction effects between different categories of UCC based on synergetic theory. To fill this gap, we constructed a panel vector autoregressive (PVAR) model to study 11 cities in the Guangdong-Hong Kong-Macao Greater Bay Area from 2000 to 2016. The ultimate goal of this study is to improve comprehensive UCC levels by forming a virtuous circle of mutual reinforcement between the four types of carrying capacity. To do so, the interaction mechanisms of the four subsystems are examined. Results show that (a) only transportation and social carrying capacity had causality between them as per the Granger causality test; (b) all four carrying capacities can support themselves (i.e., the development of economic conditions helps to improve social carrying capacity and the improvement of social carrying capacity helps to improve environmental carrying capacity); and (c) both the four carrying capacities are mostly affected by their own fluctuations. Overall transportation carrying capacity is the most important driving force among the four subsystems that interact with each other; followed by economic carrying capacity, which has promotion effect on the social and environmental aspects; social carrying capacity poses impact on the environmental dimension but not vice versa. Policy suggestions and future research directions are highlighted in the final section. • The Guangdong-Hong Kong-Macao Greater Bay Area is examined for 2000–2016. • The mean squared deviation and panel vector autoregressive methods are employed. • Transportation carrying capacity is the most significant driving force. • Economic carrying capacity could impact on social and environmental counterparts. • Social carrying capacity impact on environmental dimension but not the opposite. [ABSTRACT FROM AUTHOR]

A quantitative measure of performance that integrates national-level carbon emission profiles with key parameters of social and economic wellbeing can provide an effective management tool for policy interventions. This paper constructs non-parametric evaluation and decomposition models using hybrid measure and meta-frontier techniques. The proposed models are employed to estimate the wellbeing performance of carbon emissions (WPCE) and identify the sources of WPCE inefficiency. Empirical analyses based on the Group 20 (G20) countries for the 2000–2015 period shows the worst performance is in the BRICS country group (i.e. Brazil, Russia, India, China, and South Africa) – known for rapid growth – whereas the developed and the developing economies of the G20 group show positive trajectories of performance. As for China, its performance measure of WPCE was the lowest among the G20 indicating significant potential for further improvement. The analysis also highlights the role of managerial failure as the primary driver of inefficiency, more important than technological inefficiency in explaining efficiency loss within the G20 countries. This critical finding – the relevance and importance of managerial capability – suggests the need for a high level of attention to governance and managerial capacity to ensure continued improvements in performance on carbon emissions and human wellbeing. A lesson to be drawn from this study is that China's policies to promote a low carbon economy can benefit from increased priority given to low-carbon technological innovation for the energy system transition and enhancement of environmental governance and managerial capacity to achieve a long-term sustainability. • Welfare performance of carbon emissions (WPCE) are evaluated for G20 countries. • A hybrid non-parametric evaluation and meta-frontier techniques are employed. • Developing countries performed the best followed by developed and BRICS countries. • Gaps of WPCE are non-negligible and sources of performance loss are divergent. • Policy implications for China drawing on the cross-country comparisons are proposed. [ABSTRACT FROM AUTHOR]

Abstract The research on economic recession has been more focused on the interactions between macroeconomic and financial variables. However, whether material use has been affected during the recession period has remained under-explored. In order to fill up this gap, this study investigates the relationship between material use and economic recession, as well as other socio-economic drivers, by using the material flow analysis and the system generalized method of moments for 157 economies worldwide during 1980–2011. Results show that economic recession poses significant and negative impact on domestic material consumption at 1% level, illustrating its role as a determinant factor on material mitigation. By dividing the research sample into extractive and non-extractive economies, as well as high-, mid- and low-income groups, we again confirmed the significant negative correlations as expected. No significant sign is found between recession and physical trade balance. Besides, other drivers such as population, Gross Domestic Production (GDP) per capita and technological variables also exert marked effects at different situations. This research work provides an empirical study on how recession and other factors affect material use at various scenarios, which have essential implications for understanding material flow dynamics in different economic cycles. Graphical abstract Image 1 Highlights • Recession is the determinant factor in reducing material use. • Recession-material nexus varies along with countries of different income levels and trade patterns. • Recession has no explanatory power to physical trade balance. • Income significantly promote material consumption. • Expansion of service sector helps to reduce material consumption. [ABSTRACT FROM AUTHOR]

Abstract: A headspace solid-phase microextraction (HS-SPME) method followed by gas chromatography–mass spectrometry (GC–MS) is described for the analysis of volatile compounds in the dry rhizome of Ligusticum chuanxiong Hort. Three types of SPME fibers including PDMS, PDMS–DVB and DVB–CAR–PDMS were investigated and the best extraction was achieved with the mixed fiber DVB–CAR–PDMS. Parameters for HS-SPME in terms of temperature and time, sample amount and particle size, and desorption time were also investigated. A polar capillary column was used for the chromatographic separation. As a result, 73 compounds were determined and identified by the HS-SPME–GC–MS method with at least 20 more compounds than those in the methods available. Comparison was made between HS-SPME–GC–MS and steam distillation (SD)-GC–MS methods. Using much less sample amount, shorter extraction time and simpler procedure, HS-SPME method can achieve similar results with those by SD. In conclusion, the present method is simple, rapid and effective and can be used for the analysis of volatile compounds in medicinal plants. [Copyright &y& Elsevier]

Numerous studies have examined the correlation between economic growth and air pollution, but few focuses on the nexus between environmental regulation and <2.5 μm (PM 2.5) fine particle matter. Using Spatial Durbin Model (SDM) and Spatial Two-stage Least Squares (2SLS) methods to analyze 277 Chinese cities over the period 2002–2010, this paper finds inverted U-shaped relationships between PM 2.5 concentration and formal/informal environmental regulations for the whole and eastern and western regions. By removing the depression year of 2008, regulation effect on pollution strengthened, indicating that the main task for local governments in crisis is to avoid GDP decline rather than official promotion. Further, green technological innovation and industrial structure optimization induced by environmental regulation is shown to be beneficial for haze pollution mitigation. Some policy recommendations are proposed in conclusion. • The Spatial Models are used to examine the effect of regulation on the PM 2.5 of 277 Chinese cities during 2002–2010. • An inverted U-shaped relationship is found for the nexus. • Eastern and western China generally has an inverted U-shaped relationship. • Technical innovation and industrial structure are confirmed to be important mechanisms. [ABSTRACT FROM AUTHOR]

Abstract: A novel and rapid headspace solvent microextraction followed by gas chromatography–mass spectrometry (HSME-GC–MS) for the analysis of the volatile compounds of Foeniculum vulgare Mill is described. HSME parameters including extracting solvent, extraction temperature and time, headspace volume and particle size were optimized. As a result, benzyl alcohol was finally used for the extraction at 70°C for 20min with headspace volume of 12.1ml and particle size of 120 mesh. Under the determined conditions, the powered samples of Foeniculum vulgare Mill were directly applied for the analysis. A comparison of HSME-GC–MS, solid phase microextraction (SPME)-GC–MS and steam distillation (SD)-GC–MS methods was made and showed that the HSME-GC–MS method was simple, inexpensive and effective and can be used for the analysis of volatile compounds in traditional Chinese medicines (TCMs). [Copyright &y& Elsevier]

Abstract: A headspace solvent microextraction–gas chromatography–mass spectrometry (HSME–GC–MS) method was described for the analysis of volatile compounds from Curcuma wenyujin Y.H. Chen et C. Ling. A comparison was made between HSME–GC–MS, solid-phase microextraction (SPME)–GC–MS and steam distillation (SD)–GC–MS methods. The number of the identified compounds was 66 for HSME–GC–MS, 71 for SPME–GC–MS and 63 for SD–GC–MS, respectively. HSME–GC–MS was found to share most of the compounds in common with the other two methods. Compared with the other two methods, HSME–GC–MS has a lower cost, more choices of extraction solvents and requires a smaller amount of sample and can directly utilizes the ground powder of traditional Chinese medicines (TCMs) for the analysis. In conclusion, HSME–GC–MS method is a simple, inexpensive and effective method for the analysis of volatile compounds in TCMs. [Copyright &y& Elsevier]