In China, urbanization has been rapidly developing since the country began its economic reform in 1978. With the expansion of the urban population size and the corresponding urbanization and ...industrialization, the rapid increase in CO
2
emissions has become a major restraint on China’s economic growth. However, current studies have not paid sufficient attention to the impact of the urban population size on CO
2
emissions in China due to poor data availability. In this paper, we apply index decomposition analysis (IDA) to decompose CO
2
emissions into five elements, and we investigate both the direct and indirect impacts of the urban population size on total CO
2
emissions and per capita CO
2
emissions in China. Additionally, we empirically study the impact on 175 Chinese cities at the prefecture level and above for the first time. The results show that the urban population size significantly promotes total CO
2
emissions but curbs per capita CO
2
emissions in cities in China. A 1% increase in the urban population size will lead to a nearly 1% increase in total CO
2
emissions and a 0.3% decrease in per capita CO
2
emissions. Regarding heterogeneity, the expansion of the urban population size in the large city group drives a greater increase in CO
2
emissions than the expansion of the urban population size in other city groups. The main transmission pathways are through population density, economic agglomeration and energy intensity. Regarding the mechanism variables, high economic agglomeration leads to more CO
2
emissions, while an increase in population density and energy efficiency results in carbon mitigation. Moreover, public green areas, foreign direct investment (FDI) and technology innovation are conducive to reducing CO
2
emissions.
Genomic variants libraries are conducive to obtain dominant strains with desirable phenotypic traits. The non-homologous end joining (NHEJ), which enables foreign DNA fragments to be randomly ...integrated into different chromosomal sites, shows prominent capability in genomic libraries construction. In this study, we established an efficient NHEJ-mediated genomic library technology in Yarrowia lipolytica through regulation of NHEJ repair process, employment of defective Ura marker and optimization of iterative transformations, which enhanced genes integration efficiency by 4.67, 22.74 and 1.87 times, respectively. We further applied this technology to create high lycopene producing strains by multi-integration of heterologous genes of CrtE, CrtB and CrtI, with 23.8 times higher production than rDNA integration through homologous recombination (HR). The NHEJ-mediated genomic library technology also achieved random and scattered integration of loxP and vox sites, with the copy number up to 65 and 53, respectively, creating potential for further application of recombinase mediated genome rearrangement in Y. lipolytica. This work provides a high-efficient NHEJ-mediated genomic library technology, which enables random and scattered genomic integration of multiple heterologous fragments and rapid generation of diverse strains with superior phenotypes within 96 h. This novel technology also lays an excellent foundation for the development of other genetic technologies in Y. lipolytica.
Non-homologous end joining (NHEJ)-mediated integration is effective in generating random mutagenesis to identify beneficial gene targets in the whole genome, which can significantly promote the ...performance of the strains. Here, a novel target leading to higher protein synthesis was identified by NHEJ-mediated integration that seriously improved fatty alcohols biosynthesis in
. One batch of strains transformed with fatty acyl-CoA reductase gene (
) showed significant differences (up to 70.53-fold) in fatty alcohol production. Whole-genome sequencing of the high-yield strain demonstrated that a new target YALI0_A00913g ("A1 gene") was disrupted by NHEJ-mediated integration of partial carrier DNA, and reverse engineering of the A1 gene disruption (YlΔA1-FAR) recovered the fatty alcohol overproduction phenotype. Transcriptome analysis of YlΔA1-FAR strain revealed A1 disruption led to strengthened protein synthesis process that was confirmed by
gene expression, which may account for enhanced cell viability and improved biosynthesis of fatty alcohols. This study identified a novel target that facilitated synthesis capacity and provided new insights into unlocking biosynthetic potential for future genetic engineering in
.
With the increasing concerns of global economic recovery and climate change, the improvement of carbon emission efficiency has become extremely significant to get rid of economic and environmental ...dilemmas. Although natural resource development is usually carbon-intensive, little attention has been paid to the impact of natural resource dependence on the carbon emission efficiency. Based on the resource curse theory and the stylized facts of resource-based regions in China, for the first time, this paper proposes the hypothesis of the carbon emission efficiency curse. The hypothesis suggests that an increase of natural resource dependence can suppress the carbon emission efficiency by crowding out green technological innovation, curbing the carbon productivity of investment, and reducing population density. Furthermore, we verify the hypothesis using the instrumental variable approach and the panel data of 283 cities in China from 2004 to 2017. The results demonstrate the negative effect of natural resource dependence on the carbon emission efficiency. This finding remains robust after replacing the indicators of the key variables, altering the estimation method, and eliminating the disturbances resulting from particular samples and the low-carbon policy. The mechanism analysis indicates that natural resource dependence can crowd out green technological innovation, restrain the carbon productivity of investment, and lower population density to curb the improvement of the carbon emission efficiency. In addition, the heterogeneity analysis shows that although the carbon emission efficiency curse exists significantly in resource-based cities on average, renewable resource-based cities successfully avoid the carbon emission efficiency curse because of the optimization and transformation of economic development mode. Meanwhile, the negative impact of natural resource dependence on the carbon emission efficiency is not significant in the Two Control Zone cities and key cities for air pollution prevention and control, implying that environmental regulations are conducive to avoiding the carbon emission efficiency curse. This paper provides a novel perspective for the carbon emission efficiency improvement and low-carbon transition of China and other developing countries.
•We propose and examine the hypothesis of the carbon emission efficiency curse.•We use a panel data set of China's 283 cities and the instrumental variable approach.•We confirm the negative effect of natural resource dependence on the carbon emission efficiency.•Renewable resource-based cities successfully avoid the carbon emission efficiency curse.•Environmental regulations are conducive to avoiding the carbon emission efficiency curse.
Most of the existing research on developed countries insists that urban sprawl contributes to increasing energy consumption due to the expanding private-car-oriented transportation requirements of ...urban residents. However, in the context of China, we discover that public transportation has thrived and become one of the major travel modes for the residents, accompanied by government-led urban sprawl. Consequently, the impact of urban sprawl on transportation energy consumption in China may be highly distinct from that in Western developed countries. Therefore, we empirically investigate the impact of urban sprawl on household transportation energy consumption in China based on the Chinese Household Energy Consumption Survey and attempt to provide an appropriate explanation for this relationship. We find that urban sprawl does not lead to an increase in household transportation energy consumption in China, which is mainly due to the rapid development of a high-quality public transportation system. Specifically, urban sprawl alleviates household transportation energy consumption in China by promoting the use of public transportation among residents. Our findings contrast with previous studies on European and American cities and provide distinctive evidence of the causal relationship between urban sprawl and energy consumption. This study highlights a pathway through which developing countries can achieve sustainable urban development goals through the construction of a high-quality public transportation system.
•Features of urban sprawl and public transit differ between China and developed countries.•We examine the impact of urban sprawl on household transportation energy consumption in China.•Urban sprawl does not lead to an increase in household transportation energy consumption in China.•Public transportation system development and public service accessibility reduce household transportation energy consumption.•Urban sprawl promotes usage of public transportation in China and then reduces household transportation energy consumption.
Nuclear quantum effects (NQEs) play a crucial role in hydrogen-bonded systems due to quantum tunneling and proton fluctuation. Our understanding of how NQEs affect microstructures mainly focuses on ...bulk phases of liquids and solids but remains deficient for water clusters, including their hydrogen nuclei, hydrogen-bonded configurations, and temperature dependence. Here, we conducted ab initio molecular dynamics (MD) and path integral MD simulations to investigate the influence of NQEs on the structural properties of protonated water clusters H+(H2O) n (n = 3, 6, 9, 12). The results reveal that the NQEs become less evident as the cluster size increases due to the competition between NQEs and electrostatic interactions. Simulations of several H+(H2O)6 isomers at different temperatures indicate that the effect of elevated temperature on proton transfer is related to the initial structure. Interestingly, the process of proton transfer also involves the interconversion between Zundel-type and Eigen-type isomers. These findings significantly deepen our understanding of ion–water and water–water interactions, opening new avenues for the study of hydrated ion clusters and related systems.
Given the increasing threat of economic downturns and global warming, the governments of developing countries urgently need effective measures that can both stimulate economic development and promote ...low-carbon transitions. As a widely accepted method for stimulating economic growth, the improvement of the business environment and its effect on economic activity have been fully discussed. However, little is known about whether and how the business environment affects the low-carbon transition. By leveraging city-level data from China, this paper exploits whether and through which channels a favorable business environment promotes a low-carbon transition. We find that improving the business environment has a positive impact on carbon efficiency. This relationship is verified to be robust through various alternative tests. Additionally, it is demonstrated that enhancing the business environment can increase carbon efficiency by promoting green technology progress and stimulating new firm entry. Heterogeneity analysis indicates that the positive effect of the business environment is pronounced for cities with intensive environmental regulation, sufficient environmentally targeted fiscal expenditure, and loose economic growth requirements. This paper reveals the unintentional environmental gains of business environment optimization and provides important insights into the low-carbon transition for developing economies.
•We measure the indexes of the business environment and the carbon efficiency.•We examine the impact of the business environment on carbon efficiency.•The improvement of the business environment has a positive impact on carbon efficiency.•The business environment can improve carbon efficiency by promoting green technology progress and stimulating new firm entry.•The government plays a crucial role in business environment's effect on carbon efficiency.
Promoting sustainable development in resource-based regions is an essential issue among policymakers. Yet little is known about the effect of sustainable development strategies on income inequality. ...Leveraging the implementation of the National Sustainable Development Plan for Resource-Based Cities (2013–2020) (SDP) as a quasi-natural experiment, we adopt a difference-in-differences (DID) approach to investigate the impact of a sustainable development policy on income inequality. This paper finds that the SDP can reduce income inequality by 8.3 percentage points in resource-based cities on average, which is statistically and economically significant. The mediation effect model shows that reducing natural resource dependence is one potential and vital mechanism. Also, we find that the reduction effect of the SDP on income inequality is more pronounced in central and western regions, in growing-type and mature-type resource-based cities, and in energy-based and mineral-based cities. This paper provides valuable policy implications for developing countries to reduce income inequality and promote sustainable development.
•The SDP can significantly reduce income inequality in resource-based cities.•Declining natural resource dependence is one potential mechanism.•The reduction effect is pronounced in western regions, in mature-type resource-based cities, and in mineral-based cities.
