Plastisphere, characterized by microbial colonization on plastic debris, has attracted concern with its adverse environmental effects. The microbial features have been increasingly investigated; however, there lacks direct evidence for microplastics serving as carbon sources and enriching plastic-degrading microorganisms. Here, we obtained microbial communities from soil microplastics, analyzed the dissimilarity compared with soil, and characterized the plastic-degrading potential of isolates from plastisphere. Results showed the plastisphere communities significantly differed from soil communities and exhibited a higher relative abundance of Nocardia and Rhodococcus. To verify the selective enrichment of plastic-degrading microorganisms in the plastisphere, culture-based strategies were employed to evaluate the polyethylene (PE) degradation potential of two isolates Nocardia asteroides No.11 and Rhodococcus hoagii No.17. They could grow solely on PE and led to significant weight loss. FTIR and SEM analysis revealed the formation of new functional groups and the destruction of structural integrity on PE surfaces. Genes related to PE biodegradation were identified by genome-wide sequencing thus recognizing relevant enzymes and elucidating potential pathways. Overall, this report combined culture-free and culture-based approaches to confirm the plastic degradation potential of selectively enriched microorganisms in soil plastisphere, providing a positive perspective toward promoting microplastic biodegradation in farmland soil by enhancing natural microbial processes.
Microplastics, recognized as some of the most pervasive and enduring pollutants, have emerged as a potential threat to environmental eco-health. While much is known about the effects of microplastics on soil microorganisms, our understanding of how they interact with terrestrial organisms and the underlying mechanisms remains limited. In this study, the effects of polyethylene microplastics at a concentration of 0.5 % (w/w) on the antioxidant enzymes, gut microbiota of Eisenia fetida and the soil microbiota on days 1, 3, 7, 15, and 30 were investigated. The results indicated that exposure to microplastics slightly increased the activities of superoxide dismutase (1.22-fold on day 3, 1.12-fold on day 7) and catalase (1.10-fold on day 3, 1.09-fold on day 7) in E. fetida, while exposure markedly decreased peroxidase activity (1.33- to 1.79-fold) throughout the whole period. Both the soil microbiota and the gut microbiota of E. fetida in terms of diversity and composition were significantly affected by the microplastic amendment, and their structure tended to be similar throughout the exposure time. The family Nocardiaceae was significantly enriched in both the soil and E. fetida gut biota with microplastic exposure. Our results demonstrated that the antioxidant enzyme response of E. fetida was closely related to both the microbiota, although this relationship with the gut microbiota may have been weakened by microplastic exposure. Overall, this study furnishes new perspectives on the ecotoxicity of microplastics, revealing significant implications for the vitality of soil-dwelling organisms and the overarching health of terrestrial ecosystems.
The multiple-channel[1] sound source enhancement methods have made a great progress in recent years, especially when combined with the learning-based algorithms. However, the performance of these techniques is limited by the completeness of the training dataset, which may degrade in mismatched environments. In this paper, we propose a reconstruction Model based Self-supervised Learning (RMSL) method for sound source enhancement. A reconstruction module is used to integrate the estimated target signal and noise components to regenerate the multi-channel mixed signals, and it is connected with a separating model to form a closed loop.In this case, the optimization of the separation model can be achieved by continuously iterating the separation-reconstruction process. We use the separation error, the reconstruction error, and the signal-noise independence error as lossfunctions in the self-supervised learning process. This method is applied to the state-of-the-art sound source separation model (ADL-MVDR) and evaluated under different scenarios. Experimental results demonstrate that the proposed method can improve the performance of ADL-MVDR algorithm under different number of sound sources, bringing about 0.5 dB to 1 dB Si-SNR gain, while maintaining good clarity and intelligibility in practical application.
A visa-free policy is a tool for attracting foreign tourists, but existing studies evaluating its effects do not consider spatial spillover. This study, therefore, examined the effects of visa policies on urban inbound tourism with spatial spillover. This study used the implementation of the 72-hr visa-free transit policy in China as a natural experiment and employed a spatial difference-in-differences approach. The results show that the implementation of the 72-hr visa-free transit policy had no significant effect on the number of foreign tourists, but can reduce the average length of stay for foreign tourists. It also shows that there is a significant spatial spillover effect on the flow of foreign tourists. The results indicate the importance of spatial spillover in the evaluation of the impact of visa policy on inbound tourism, providing empirical evidence for further improving visa-free policies and urban tourism development.
Mega-events such as the Olympic Games, the World Cup, the World Expos, and the G20 Summit play important roles in international political economy in the age of globalization. But we know little about how they shape domestic politics and policy processes in their host countries. China has emerged as the leading host of various sports, cultural, economic, and political mega-events in the past decades. Employing an original panel dataset of Chinese cities from 2001 to 2019, we find that cities that host mega-events gain an advantage in bargaining with central bureaucracies for policy resources. Using subway investments as an example, we demonstrate that host cities not only obtained centrally regulated infrastructure investments that directly serve the needs of the events, but also achieve development that they otherwise could not. The result is robust with two-way fixed effects models and after accounting for various alternative explanations. We show that host cities gain advantage because the events capture the attention of national leaders. National leaders have power over central bureaucrats’ careers and thus steer their decisions, and they see the success of mega-events as an opportunity to project national strengths. Our findings highlight the domestic policy consequences of international events in the age of China’s rapid rise and integration with the world.
Populism has recently enjoyed success in Europe, the US, and beyond. Populist leaders and their supporters have accused “mainstream” media of being part of a “corrupt” elite that misrepresents the will of the virtuous “people.” Distrust of the media has also prompted the rejection of traditional media sources for political information and given prominence to alternative and hyperpartisan sources such as Breitbart. However, limited research exists concerning who consumes hyperpartisan media, how the websites of hyperpartisan media are interconnected, and what content is presented in hyperpartisan news. By combining cross-national surveys with large-scale digital trace datasets of website visits, this paper demonstrates the link between populist party support and hyperpartisan media visits. It also identifies influential sources of hyperpartisan news by analyzing the audience similarity networks of these websites and reveals country-level variations in hyperpartisan news and the dominance of US politics among the identified hyperpartisan news topics.
Financial inclusion and energy poverty have an interactive relationship; however, this two-way relationship lacks sufficient research. This study investigates the two-way mechanisms of financial inclusion, energy poverty, and neighborhood spillover effects. Using a spatial simultaneous equation model, this study examines 2615 Chinese rural households in 2020. Results reveal a statistically significant positive interaction between financial inclusion and energy poverty. In addition, the neighborhood spillover effects of financial inclusion and energy poverty are both significantly positive, whereas their neighborhood interaction spillover effects are significantly negative.
The COVID-19 pandemic, characterized by its highly contagious nature and devastating death toll, posed a dual threat to both physical and psychological well-being. As a potential intervention to alleviate the psychological impact, values-affirmation involves individuals engaging in the activity of writing about their core values. While its effectiveness in non-WEIRD (i.e. Western, Educated, Industrialized, Rich, Democratic) populations, notably among Chinese adults, has been confirmed, it remains largely unexplored whether the intervention can promote mental health in Chinese adolescents, especially in the context of the COVID-19 pandemic. The purpose of this study thus is to provide the first empirical evaluation of this intervention in promoting well-being and alleviating psychological distress among Chinese adolescents during the COVID-19 pandemic. A total of 2,234 students from 112 secondary schools in China were randomly assigned to an affirmation or control condition. The study found that self-affirmation intervention improved students' life satisfaction, mental health, and self-esteem, as well as buffered a decline of their purpose in life; however, no effects were found for clinical measures of depression, anxiety, and loneliness. The results suggest that self-affirmation interventions, while having limited effects on clinically relevant outcomes, can be an effective approach to boost well-being in adolescents during a major crisis, including in a more historically collectivist culture. Implications for self-affirmation theory and cultural psychology, as well as avenues for future research, are discussed.
Using 13,584 observations of 4772 undergraduate students enrolled in 523 online classes offered synchronously at a research university in China, and using online-learning platform data and administrative data, this paper examines the impacts of class attendance on academic performance. Based on student-level and course-level fixed effects models with a unique set of student-course level control variables, this paper finds class attendance to have a significantly positive impact on academic performance. This effect is larger for low-performing students and smaller for students in courses with larger class sizes. The above findings survive a number of robustness checks, including a bounding technique, restricting sample to compulsory courses and limiting variation in attendance caused by whole day absence.
The successful implementation of in-situ bioremediation of nonaqueous-phase liquid (NAPL) contamination in soil-groundwater systems is greatly influenced by the migration performance of NAPL-degrading bacteria. However, the impact and mechanisms of NAPL on the migration/retention of pollutant-degrading bacteria remain unclear. This study investigated the migration/retention performance of A. lwoffii U1091, a strain capable of degrading diesel while producing surfactants, in porous media without and with the presence of mono- and multicomponent NAPL (n-dodecane and diesel) under environmentally relevant conditions. The results showed that under all examined conditions (5 and 50 mM NaCl solution at flow rates of 4 and 8 m/d), the presence of n-dodecane/diesel in porous media could reduce the migration and enhance retention of A. lwoffii in quartz sand columns. Moreover, comparing with mutlicomponent NAPLs of n-dodecane, the monocomponent NAPLs (diesel) exhibited a greater reduction effect on the retention of A. lwoffii in porous media. Through systemically investigating the potential mechanisms via tracer experiment, visible chamber experiment, and theoretical calculation, we found that the reduction in porosity, repulsive forces and movement speeds, the presence of stagnant flow zones in porous media, particularly the biosurfactants generated by A. lwoffii contributed to the enhanced retention of bacteria in NAPL-contaminated porous media. Moreover, owing to presence of the greater amount of hydrophilic components in diesel than in n-dodecane, the available binding sites for the adsorption of bacteria were lower in diesel, resulting in the slightly decreased retention of A. lwoffii in porous media containing diesel than n-dodecane. This study demonstrated that comparing with porous media without NAPL contamination, the retention of strain capable of degrading NAPL in porous media with NAPL contamination was enhanced, beneficial for the subsequent biodegradation of NAPL.
The mitigating effects of straw burning bans on air pollution are widely known; however, their effects on indoor air pollution are generally ignored. Cooking fuel use is an important factor that affects indoor air quality. However, the debate over the pros and cons of a province-wide ban on straw burning has been a major issue in environmental economics. By utilizing household survey data, this study investigates the role of straw burning bans on cooking fuel use in households. To infer causal relationships, difference-in-difference models that compare households in provinces with and without a complete ban on open straw burning (COSB) are employed. The results show that COSBs promote the use of clean cooking fuels and discourage the use of firewood for cooking by households. These results hold true after a series of robustness tests, such as parallel trends and placebo tests. However, the results show that the effect of COSBs on the household use of coal as a cooking fuel is not significant. Further analysis shows heterogeneity in the effects of COSBs on the use of household cooking fuels. Thus, COSBs promote the conversion to cleaner cooking fuels in rural households, but the implementation of these policies needs to be contextualized.
Abstract The insufficient exciton (e−-h+ pair) separation/transfer and sluggish two-electron water oxidation are two main factors limiting the H2O2 photosynthetic efficiency of covalent organic frameworks (COFs) photocatalysts. Herein, we present an alternative strategy to simultaneously facilitate exciton separation/transfer and reduce the energy barrier of two-electron water oxidation in COFs via a dicyano functionalization. The in situ characterization and theoretical calculations reveal that the dicyano functionalization improves the amount of charge transfer channels between donor and acceptor units from two in COF-0CN without cyano functionalization to three in COF-1CN with mono-cyano functionalization and four in COF-2CN with dicyano functionalization, leading to the highest separation/transfer efficiency in COF-2CN. More importantly, the dicyano group activates the neighbouring C atom to produce the key *OH intermediate for effectively reducing the energy barrier of rate-determining two-electron water oxidation in H2O2 photosynthesis. The simultaneously enhanced exciton separation/transfer and two-electron water oxidation in COF-2CN result in high H2O2 yield (1601 μmol g−1 h−1) from water and oxygen without using sacrificial reagent under visible-light irradiation. COF-2CN can effectively yield H2O2 in water with wide pH range, in different real water samples, in scaled-up reactor under natural sunlight irradiation, and in continuous-flow reactor for consecutively producing H2O2 solution for water decontamination.
