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1.
J Environ Manage ; 360: 121175, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38744208

RESUMO

The fiscal system plays an important role in the government's environmental governance efforts. There is currently no consensus on how fiscal structure adjustments impact pollution and carbon reduction. This paper uses China's fiscal "province-managing-county" reform (FPMCR) implemented in 2004 as a quasi-natural experiment, utilizing panel data from 1670 counties in China from 2000 to 2020 to investigate the impact of fiscal decentralization on reduction pollution and carbon emissions (RPCE), as well as its underlying mechanisms. The results show that (1) from 2000 to 2020, China's RPCE shows an overall trend of fluctuating increase, with its value turning positive after 2013. China's RPCE exhibits a spatial pattern characterized by "lower in the north, higher in the south; higher in the east, lower in the west". (2) After implementing FPMCR, the RPCE levels in reformed counties decreased by -1.44%, showing that reformed county-level governments prioritize economic development over environmental protection. (3) The mechanism analysis found that after implementing FPMCR, reformed counties experienced a 9.16% increase in nighttime light intensity (NLI), and a 3.99% and 4.34% increase in the number of large-scale industrial enterprises (NLIE) and industrial agglomeration (IA), respectively. This suggests that FPMCR leads to radical urbanization and rapid industrialization in counties, which is detrimental to the improvement of RPCE levels. (4) The spatial heterogeneity analysis found that FPMCR's impact coefficient on RPCE levels in the eastern regions is -1.96%, while in the western regions it is -1.16%. This indicates that reformed counties in the eastern regions are more likely to invest expanded fiscal resources in economic development projects, leading to a decrease in RPCE levels. (5) The temporal heterogeneity analysis found that after the promulgation of the "Three-Year Action Plan to Win the Blue Sky Defense Battle" in 2018, the adverse impact of FPMCR on RPCE is completely reversed, leading to a 1.76% increase in RPCE levels. (6) Further analysis reveals that localizing leaders can slow down the promotion of county-level urbanization and industrialization by the FPMCR, benefiting the improvement of RPCE levels. In other words, "the outsider monk will not recite scriptures as well as a local one". This study has clarified the causal relationship and underlying mechanisms between fiscal decentralization and environmental governance, providing reliable theoretical support for optimizing grassroots fiscal systems and reducing environmental pollution in other transitional economies. It enriches the field of environmental economics related to fiscal decentralization.


Assuntos
Poluição Ambiental , China , Poluição Ambiental/prevenção & controle , Carbono , Desenvolvimento Econômico , Conservação dos Recursos Naturais
2.
Angew Chem Int Ed Engl ; : e202407121, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38775229

RESUMO

Electrocatalytic hydrogenation of unsaturated aldehydes to unsaturated alcohols is a promising alternative to conventional thermal processes. Both the catalyst and electrolyte deeply impact the performance. Designing the electrode-electrolyte interface remains challenging due to its compositional and structural complexity. Here, we employ the electrocatalytic hydrogenation of 5-hydroxymethylfurfural (HMF) as a reaction model. The typical cationic surfactant, cetyltrimethylammonium bromide (CTAB), and its analogs are employed as electrolyte additives to tune the interfacial microenvironment, delivering high-efficiency hydrogenation of HMF and inhibition of the hydrogen evolution reaction (HER). The surfactants experience a conformational transformation from stochastic distribution to directional assembly under applied potential. This oriented arrangement hampers the transfer of water molecules to the interface and promotes the enrichment of reactants. In addition, near 100 % 2,5-bis(hydroxymethyl)furan (BHMF) selectivity is achieved, and the faradaic efficiency (FE) of the BHMF is improved from 61 % to 74 % at -100 mA cm-2. Notably, the microenvironmental modulation strategy applies to a range of electrocatalytic hydrogenation reactions involving aldehyde substrates. This work paves the way for engineering advanced electrode-electrolyte interfaces and boosting unsaturated alcohol electrosynthesis efficiency.

3.
J Am Chem Soc ; 146(11): 7575-7583, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38466222

RESUMO

Electrocatalytic reactions taking place at the electrified electrode-electrolyte interface involve processes of proton-coupled electron transfer. Interfacial protons are delivered to the electrode surface via a H2O-dominated hydrogen-bond network. Less efforts are made to regulate the interfacial proton transfer from the perspective of interfacial hydrogen-bond network. Here, we present quaternary ammonium salt cationic surfactants as electrolyte additives for enhancing the H2O2 selectivity of the oxygen reduction reaction (ORR). Through in situ vibrational spectroscopy and molecular dynamics calculation, it is revealed that the surfactants are irreversibly adsorbed on the electrode surface in response to a given bias potential range, leading to the weakening of the interfacial hydrogen-bond network. This decreases interfacial proton transfer kinetics, particularly at high bias potentials, thus suppressing the 4-electron ORR pathway and achieving a highly selective 2-electron pathway toward H2O2. These results highlight the opportunity for steering H2O-involved electrochemical reactions via modulating the interfacial hydrogen-bond network.

4.
Sci Bull (Beijing) ; 68(19): 2190-2199, 2023 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-37580202

RESUMO

Electrocatalytic conversion of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF) presents a compelling strategy for the production of premium chemicals via the utilization of renewable energy sources. Exploring efficient catalytic systems to obtain highly selective BHMF has remained a giant challenge. A design strategy is proposed here to regulate active hydrogen (Hads) production in rhodium (Rh) nanoparticles grown on Cu nanowires (RhCu NWs) catalyst, which achieves a faradaic efficiency (FE) of 92.6% in the electrocatalytic reduction of HMF to BHMF at -20 mA cm-2 with no degradation in performance after 8 cycles. Kinetic investigations and electron spin resonance (ESR) spectroscopy reveal that the incorporation of Rh accelerates the water dissociation and facilitates the generation of Hads. In situ attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) further demonstrates that the Rh component boosts the proportion of ordered weakly hydrogen-bonded water molecules on the catalyst surface, which is much easier to dissociate. The construction of an interfacial Hads-rich environment promotes the HMF intermediates binding with Hads to BMHF, thereby suppressing the formation of undesired dimers. This work demonstrates the promise of altering the interfacial water environment as a strategy to boost the electrosynthetic properties of biomass-derived products toward value-added outcomes.

5.
Clin Oral Investig ; 27(9): 5153-5170, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37428274

RESUMO

OBJECTIVES: We aimed to explore the osteogenic potential of periodontal ligament stem cells (PDLSCs) in bioprinted methacrylate gelatine (GelMA) hydrogels in vitro and in vivo. MATERIALS AND METHODS: PDLSCs in GelMA hydrogels at various concentrations (3%, 5%, and 10%) were bioprinted. The mechanical properties (stiffness, nanostructure, swelling, and degradation properties) of bioprinted constructs and the biological properties (cell viability, proliferation, spreading, osteogenic differentiation, and cell survival in vivo) of PDLSCs in bioprinted constructs were evaluated. Then, the effect of bioprinted constructs on bone regeneration was investigated using a mouse cranial defect model. RESULTS: Ten percent GelMA printed constructs had a higher compression modulus, smaller porosity, lower swelling rate, and lower degradation rate than 3% GelMA. PDLSCs in bioprinted 10% GelMA bioprinted constructs showed lower cell viability, less cell spreading, upregulated osteogenic differentiation in vitro, and lower cell survival in vivo. Moreover, upregulated expression of ephrinB2 and EphB4 protein and their phosphorylated forms were found in PDLSCs in 10% GelMA bioprinted constructs, and inhibition of eprhinB2/EphB4 signalling reversed the enhanced osteogenic differentiation of PDLSCs in 10% GelMA. The in vivo experiment showed that 10% GelMA bioprinted constructs with PDLSCs contributed to more new bone formation than 10% GelMA constructs without PDLSCs and constructs with lower GelMA concentrations. CONCLUSIONS: Bioprinted PDLSCs with high-concentrated GelMA hydrogels exhibited enhanced osteogenic differentiation partially through upregulated ephrinB2/EphB4 signalling in vitro and promoted bone regeneration in vivo, which might be more appropriate for future bone regeneration applications. CLINICAL RELEVANCE: Bone defects are a common clinical oral problem. Our results provide a promising strategy for bone regeneration through bioprinting PDLSCs in GelMA hydrogels.


Assuntos
Hidrogéis , Osteogênese , Hidrogéis/farmacologia , Hidrogéis/química , Hidrogéis/metabolismo , Ligamento Periodontal , Gelatina/farmacologia , Gelatina/química , Gelatina/metabolismo , Células-Tronco , Regeneração Óssea , Diferenciação Celular , Células Cultivadas
6.
Nutrients ; 14(17)2022 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-36079780

RESUMO

A lack of adequate exercise threatens human health, weakening human capital accumulation. The relationship between exercise and income has become the focus of attention in health economics. In terms of reducing body weight and improving physical fitness, diet and physical exercise are intertwined and become effective ways to shape a healthy state. Based on individual-level survey data from China, this study quantified the economic returns of habitual exercise behavior by using an endogenous switching regression model (ESRM) to eliminate selection bias. The study shows that (1) participants in the group with regular exercise behavior increased their income by 3.79% compared with those not exercising regularly; (2) for the group with no regular exercise behavior, regular exercise increased their income by 13.36% compared with those not exercising regularly. Additionally, empirical evidence shows that both drinking and smoking can significantly increase individual income, despite unhealthy habits. These results suggest that the habit of regular physical activity plays a vital role in increasing individual income and improving overall national health, and the effect of individual behavior on income is affected by national culture. The outcomes are empirical evidence for the Chinese government to promote Healthy China Action and support developing countries worldwide to enable habitual exercise, stimulating a policy of exercise behavior.


Assuntos
Exercício Físico , Aptidão Física , China , Nível de Saúde , Humanos , Renda , Inquéritos e Questionários
7.
Nat Commun ; 13(1): 4602, 2022 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-35933480

RESUMO

Designing efficient catalysts and understanding the underlying mechanisms for anodic nucleophile electrooxidation are central to the advancement of electrochemically-driven technologies. Here, a heterostructure of nickel boride/nickel catalyst is developed to enable methanol electrooxidation into formate with a Faradaic efficiency of nearly 100%. Operando electrochemical impedance spectroscopy and in situ Raman spectroscopy are applied to understand the influence of methanol concentration in the methanol oxidation reaction. High concentrations of methanol inhibit the phase transition of the electrocatalyst to high-valent electro-oxidation products, and electrophilic oxygen species (O* or OH*) formed on the electrocatalyst are considered to be the catalytically active species. Additional mechanistic investigation with density functional theory calculations reveals that the potential-determining step, the formation of *CH2O, occurs most favorably on the nickel boride/nickel heterostructure rather than on nickel boride and nickel. These results are highly instructive for the study of other nucleophile-based approaches to electrooxidation reactions and organic electrosynthesis.

8.
Sci Total Environ ; 846: 157153, 2022 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-35842146

RESUMO

This study used panel data for 2166 county-level units in China between 2000 and 2017 to characterize carbon productivity's temporal and spatial evolution in Chinese counties. The "catch-up effect" of carbon offsets between counties was examined, and this was used to measure the carbon offset potential and analyze its spatial differences. The results indicated that: (1) China's carbon productivity increased from 2000 to 2017; carbon productivity in eastern China was the highest, and carbon productivity in northeast China was the lowest. A polarization to unipolarization evolutionary trend was evident. (2) Considering the spatial differences in carbon productivity, the overall difference in carbon productivity in China from 2000 to 2017 first decreased and then increased; the contribution rate of differences between cities and counties to the overall difference was relatively stable, at around 39.88 %. The contribution rate of the differences between zones to the overall difference was the lowest, remaining stable at around 2.49 %. (3) In terms of the spatial distribution of the carbon offset potential, the eastern region exhibited the highest average carbon offset potential. The carbon offset potential of China exhibited a "high in the north and low in the south; low in the west and high in the east" spatial pattern.


Assuntos
Carbono , Eficiência , Carbono/análise , China , Cidades , Desenvolvimento Econômico
9.
Artigo em Inglês | MEDLINE | ID: mdl-35682072

RESUMO

China is the largest carbon emitter in the world, with agricultural carbon emissions accounting for 17% of China's total carbon emissions. Agricultural carbon emission reduction has become the key to achieving the "Double Carbon" goal. At the same time, the role of the digital economy in achieving the "dual carbon" goal cannot be ignored as an important engine to boost the high-quality development of China's economy. Therefore, this paper uses the panel data of 30 provinces in mainland China from 2011 to 2019 to construct a spatial Durbin model and a mediation effect model to explore the impact of the digital economy on agricultural carbon intensity and the mediating role of agricultural technological progress. The research results show that: (1) China's agricultural carbon intensity fluctuated and declined during the study period, but the current agricultural carbon intensity is still at a high level; (2) The inhibitory effect of the digital economy on agricultural carbon intensity is achieved by promoting agricultural technological progress, and the intermediary role of agricultural technological progress has been verified; (3) The digital economy can significantly reduce the carbon intensity of agriculture, and this inhibition has a positive spatial spillover effect. According to the research conclusions, the government should speed up the development of internet technology and digital inclusive finance, support agricultural technology research and improve farmers' human capital, and strengthen regional cooperation to release the contribution of digital economy space.


Assuntos
Agricultura , Carbono , Carbono/análise , Dióxido de Carbono/análise , China , Desenvolvimento Econômico , Humanos , Tecnologia
10.
Environ Sci Pollut Res Int ; 29(51): 78009-78028, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35689770

RESUMO

China has the highest carbon dioxide emissions worldwide. Exploring the mechanism of fiscal decentralisation on agricultural carbon intensity can help China reach its carbon peak and become carbon neutral. This study used panel data for 30 provinces in Mainland China from 2000 to 2019 and constructed a spatial Durbin model to investigate the spatial-temporal patterns and internal relationships among fiscal decentralisation, environmental regulation, and agricultural carbon intensity. The results indicated that (1) from 2000 to 2019, the agricultural carbon intensity showed a downward trend and showed a spatial pattern of 'high in the north and low in the south'. The degree of fiscal decentralisation has gradually increased, and the spatial pattern of 'high in the north and low in the south' has also emerged. The intensity of environmental regulation continues to increase, and the intensity of environmental regulation in inland areas is higher than that in coastal areas. (2) From 2000 to 2019, the global Moran index of agricultural carbon intensity showed a development trend of first rising and then falling, and the spatial correlation changed from strong to weak. Agricultural carbon intensity tends to develop from polarisation to balanced development. (3) Both fiscal decentralisation and environmental regulation can reduce agricultural carbon intensity, and environmental regulation has a negative spatial spillover effect. (4) Under the influence of fiscal decentralisation, environmental regulation is not conducive to reducing agricultural carbon intensity due to the characteristics of 'race to the bottom', causing the 'green paradox' effect. (5) Environmental regulation and fiscal decentralisation in main grain producing areas have less impact on agricultural carbon intensity than in non-main grain producing areas. Therefore, the central government should focus on optimising the fiscal decentralisation system, formulating a differentiated agricultural carbon emission control system, regulating competition among local governments, and optimising a political performance evaluation system.


Assuntos
Agricultura , Dióxido de Carbono , Dióxido de Carbono/análise , Governo Local , Política , China , Desenvolvimento Econômico
11.
Artigo em Inglês | MEDLINE | ID: mdl-35742624

RESUMO

Declining fertility rates pose challenges to global economic, social, cultural and political development. Low fertility rates among rural floating populations are exacerbating these challenges. However, it is not clear whether and to what extent rural population mobility (RPM) has reduced migrants' willingness to have children. At the same time, rural migration may represent a self-selection behavior (i.e., selection bias), and traditional measurement methods may be insufficient for effectively estimating the quantitative impacts of rural migration. Accordingly, the data from 1734 rural households from 28 provinces in mainland China were collected in the current study, and endogenous switching regression (ESR) models were used to correct the selection bias to quantitatively evaluate the impacts of RPM on fertility intention. The results revealed the following: (1) For rural residents who choose to move, if they chose not to move, their willingness to give birth would increase by 19.820%, their willingness to have female children would increase by 48.526%, and their willingness to have male children would drop by 26.711%. (2) For rural residents who choose not to move, if they chose to move, their willingness to give birth would drop by 55.982%, their willingness to have female children would drop by 18.294%, and their willingness to have male children would drop by 55.106%. (3) For eastern rural residents who choose to move, if they chose not to move, their willingness to give birth would decrease by 40.273%. For midwestern rural residents who choose to move, if they chose not to move, their willingness to give birth would increase by 24.786%. (4) For eastern rural residents who choose not to move, if they chose to move, their willingness to give birth would increase by 11.032%. (5) For midwestern rural residents who choose not to move, if they chose to move, their willingness to give birth would drop by 71.744%. The abovementioned findings can provide research support for other low-fertility countries or regions toward increasing fertility rates and addressing any imbalances in current gender ratios. They can also help to provide realistic strategies for alleviating the global population crisis.


Assuntos
Intenção , População Rural , China , Demografia , Países em Desenvolvimento , Feminino , Fertilidade , Humanos , Masculino , Dinâmica Populacional , Política Pública
12.
Artigo em Inglês | MEDLINE | ID: mdl-35627642

RESUMO

Globally, all countries regard the development of economic zones around basins as the focus and main axis of national economic construction. The economic development of basin areas must consider the constraints of environmental protection, which requires local governments to adopt a coordinated development approach to the green economy. The Chengdu-Chongqing Economic Circle is located in the upper reaches of the Yangtze River Basin and will be built into a growth pole for China's economic growth. This paper uses the panel data of 16 cities in the Chengdu-Chongqing Economic Circle from 2005 to 2019 and measures the level of coordinated development of the green economy among cities. Using fixed effect regression models, this paper identified the factors driving the coordinated development level of the urban green economy. The results show that (1) the overall trend of coordinated development of green economy in the Chengdu-Chongqing economic circle is enhanced; (2) the pulling force includes the similarity of economic agglomeration and regional openness, the resonance force includes the similarity of traffic and industrial structure, the pushing force comes from the central city; (3) in the urban agglomeration with double centers, the cooperation and competition between two "pole" cities may coexist.


Assuntos
Conservação de Recursos Energéticos , Urbanização , Cidades , Desenvolvimento Econômico , Rios/química
13.
Environ Sci Pollut Res Int ; 29(29): 44832-44844, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35138544

RESUMO

People's weak perceptions of environmental pollution (PEP) threaten the achievement of the Global Sustainable Goals, especially in rural areas. However, Internet use may improve farmer's PEP. Thus, based on survey data from rural China, this study uses an endogenous switching regression model (ESRM) to remove the selection bias and quantitatively evaluate the impact of Internet use on the farmers' PEP. The results of this study show that (1) for group of farmers using the Internet, if they do not use the Internet, their PEP may decrease by 91.004% and (2) for group of farmers not using the Internet, if they use the Internet, their PEP may increase by 100.160%. These results provide the evidence for developing countries aiming to improve their residents' PEP and provide a new path for solving the problem of global environmental pollution and realizing sustainability.


Assuntos
Agricultura , Fazendeiros , Agricultura/métodos , China , Poluição Ambiental , Humanos , Uso da Internet , Percepção , População Rural
14.
Artigo em Inglês | MEDLINE | ID: mdl-35162139

RESUMO

At present, the world's countryside needs to be revitalized urgently, and cultivated land is the critical factor in promoting the countryside's revitalization. The reduction of uncultivated land contributes to the efficient use of rural land resources, contributing to global rural revitalization. This study uses data from 3938 Chinese peasant households conducted in 2014 and the OLS method to investigate the quantitative impact of institutional social insurance on cultivated land abandonment. The empirical results point to the following conclusions: (1) Institutional social insurance will weaken the social insurance function of land, which will lead to the generation of peasant households' cultivated land abandonment. More specifically, for every 1% increase in the level of institutional social insurance of peasant households, the area of cultivated land abandoned increased by 0.002 mu; (2) The influence of institutional social insurance on peasant households' cultivated land abandonment is heterogeneous, that is, endowment insurance can weaken the social insurance function of land more than medical insurance, and households with a higher proportion of pensioners are more likely to abandon cultivated land. This study's conclusions may help understand the relationship between institutional and non-institutional social insurance and provide a reference for the effective use of cultivated land resources in the global rural revitalization.


Assuntos
População Rural , Previdência Social , Agricultura/métodos , China , Meio Ambiente , Características da Família , Humanos
15.
Artigo em Inglês | MEDLINE | ID: mdl-31557866

RESUMO

Prior studies have fully explored the impacts of rural labor migration on land use forms. In contrast to prior studies, this study focuses on the health status of rural households and its quantitative impacts on cropland abandonment (CA). More specifically, under the guidance of the theoretical mechanism of "household health affects CA by labor supply", this study employs survey data from 8031 households collected in 27 Chinese provinces in 2014 to explore the quantitative impacts of household health on CA. The results are as follows. (1) The higher the level of household health is, the less CA there is. (2) Compared with males, the impact of female health status on CA is more obvious. Thus, the relationship between household health and CA matters, not only because it may help to theoretically enhance the understanding of the importance of health in peasant households, but also because it may help to practically provide references for effective policies of CA from the perspective of rural medical services.


Assuntos
Produtos Agrícolas , Emigração e Imigração , Nível de Saúde , População Rural , China , Características da Família , Feminino , Humanos , Masculino
16.
Sci Total Environ ; 656: 129-139, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30504015

RESUMO

Alkyl nitrates (RONO2) are important reservoirs of nitrogen oxides and play key roles in the tropospheric chemistry. Two phases of intensive campaigns were conducted during February-April and June-July of 2017 at a rural coastal site and in open oil fields of the Yellow River Delta region, northern China. C1-C5 alkyl nitrates showed higher concentration levels in summer than in winter-spring (p < 0.01), whilst their parent hydrocarbons showed an opposite seasonal variation pattern. The C3-C5 RONO2 levels in the oil fields were significantly higher than those in the ambient rural air. Alkyl nitrates showed well-defined diurnal variations, elucidating the effects of in-situ photochemical production and regional transport of aged polluted plumes. Backward trajectory analysis and fire maps revealed the significant contribution of biomass burning to the observed alkyl nitrates and hydrocarbons. A simplified sequential reaction model and an observation-based chemical box model were deployed to diagnose the formation mechanisms of C1-C5 RONO2. The C3-C5 RONO2 were mainly produced from the photochemical oxidation of their parent hydrocarbons (i.e., C3-C5 alkanes), whilst C1-C2 RONO2 compounds have additional sources. In addition to parent hydrocarbons, longer alkanes with >4 carbon atoms were also important precursors of alkyl nitrates in the oil fields. This study demonstrates the significant effects of oil field emissions and biomass burning on the volatile organic compounds and alkyl nitrate formation, and provides scientific support for the formulation of control strategies against photochemical air pollution in the Yellow River Delta region.

17.
Artigo em Inglês | MEDLINE | ID: mdl-30135363

RESUMO

Alleviating cropland misallocation is helpful for the sustainable development of agriculture. Does off-farm employment inevitably result in cropland misallocation (e.g., cropland abandonment) and threaten the sustainable development of agriculture? This study differs from prior studies in its view that off-farm employment does not necessarily result in cropland abandonment. Specifically, the study employs survey data from 8031 peasant households from 27 provinces in rural China and spatial statistics to analyze the distribution of off-farm employment and cropland abandonment. Empirical models (i.e., IV-Probit and IV-Tobit) are used to examine the quantitative relation between off-farm employment and cropland abandonment. The results are as follows. (1) The spatial distribution of off-farm employment or cropland abandonment differs among regions. Regions with a higher rate of off-farm employment show more cropland abandonment but a lower average area of cropland abandonment. (2) Off-farm employment has a significant and positive correlation with cropland abandonment. However, its square has a significant and negative correlation with cropland abandonment; i.e., there is an inverted U-shaped relationship between off-farm employment and cropland abandonment, with the turning point occurring at 46.00% off-farm employment. (3) Off-farm employment has a significant and positive correlation with the area of cropland abandonment. However, its square has a significant and negative correlation with the area; i.e., there is an inverted U-shaped relationship between off-farm employment and area, with the turning point occurring at 44.50% off-farm employment. This study reveals the relationship between off-farm employment and cropland abandonment and provides policymakers with references for use in developing sustainable agriculture.


Assuntos
Conservação dos Recursos Naturais/estatística & dados numéricos , Produtos Agrícolas , Emprego/estatística & dados numéricos , Adulto , Idoso , Agricultura/métodos , China , Países em Desenvolvimento , Humanos , Pessoa de Meia-Idade , População Rural
18.
Environ Sci Pollut Res Int ; 25(8): 7589-7599, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29282668

RESUMO

Excessive fertilization is a common agricultural practice that has largely reduced soil nutrient retention capacity and led to nutrient leaching in China. To reduce nutrient leaching, in this study, we evaluated the application of biochar, compost, and biochar-compost on soil properties, leaching water quality, and cucumber plant growth in soils with different nutrient levels. In general, the concentrations of nutrients and heavy metals in leaching water were higher under high-nutrient conditions than under low-nutrient conditions. Both biochar and compost efficiently enhanced soil cation exchange capacity (CEC), water holding capacity (WHC), and microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP), reduced the potential leaching of nutrients and heavy metals, and improved plant growth. The efficiency of biochar and compost in soil CEC, WHC, MBC, MBN, and MBP and plant growth was enhanced when applied jointly. In addition, biochar and biochar-enhanced compost efficiently suppressed plant-parasitic nematode infestation in a soil with high levels of both N and P. Our results suggest that biochar-enhanced compost can reduce the potential environmental risks in excessively fertilized vegetable soils.


Assuntos
Carbono/química , Carvão Vegetal/química , Cucumis sativus/química , Metais Pesados/química , Nitrogênio/análise , Fósforo/análise , Poluentes do Solo/análise , Agricultura , Animais , Biomassa , China , Compostagem , Cucumis sativus/crescimento & desenvolvimento , Nematoides , Nitrogênio/química , Nutrientes , Desenvolvimento Vegetal , Poluentes do Solo/química , Água
19.
Appl Biochem Biotechnol ; 179(6): 986-96, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26961187

RESUMO

Reducing the viscosity of molasses environmentally and selectively removing the harmful ingredients for microbes are the keys to promoting the bioavailability of molasses. A simple and environmental in situ pretreatment method integrating surfactants and alkali was developed to reduce the viscosity of molasses prior to L-lysine production using Escherichia coli ZY0217. Adding activated carbon and modified orange peel based on the in situ pretreatment process effectively removed pigments and excessive zinc in the molasses and also significantly increased the cell growth and L-lysine yield from E. coli ZY0217. The experimental results showed that a mixture of secondary alkane sulfonate, an anionic surfactant, and HodagCB-6, a non-ionic surfactant, effectively reduced the viscosity of the molasses more so than any single surfactant. When the surfactant mixture was added at a concentration of 0.04 g/L to the molasses, the ω value was 0.4, and when ammonia was added at 0.6 %, the lowest viscosity of 705 mPa · s was obtained. Further, 91.5 % of the color and 86.68 % of the original levels of zinc were removed using an activated carbon and modified orange peel treatment on the molasses with the lowest viscosity, which further promoted cell growth and L-lysine production. In the fed-batch cultivation process, the L-lysine concentration achieved using a constant-speed feeding strategy was 45.89 g/L, with an L-lysine yield of 27.18 %, whereas the L-lysine yield from untreated molasses was only 10.13 %. The increase in L-lysine yield was related to the reduced viscosity and the detoxification of the molasses. Lastly, the pretreatment was found to significantly enhance the conversion of sugars in the molasses to L-lysine.


Assuntos
Beta vulgaris/química , Reatores Biológicos , Lisina/biossíntese , Escherichia coli/genética , Fermentação , Glucose/química , Lisina/química , Engenharia Metabólica , Melaço
20.
Fertil Steril ; 101(1): 51-57.e1, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24112532

RESUMO

OBJECTIVE: To investigate the association between smoking, semen quality, and the histone-to-protamine transition ratio in mature sperm. DESIGN: Biochemical and molecular analysis in human samples and a cell line. SETTING: Andrology laboratory in a university-affiliated hospital. PATIENT(S): Semen samples from 147 heavy smokers and 175 nonsmokers receiving infertility treatment. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Basic semen parameters, histone-to-protamine ratios, and number of sperm cells with abnormal histone transition were calculated. The relative messenger RNA (mRNA) expression levels of protamine 1 and protamine 2 were assayed in human sperm and in TM3 cells exposed to cigarette smoke condensate. T tests, Spearman tests, and nonparametric Mann-Whitney U tests were used to detect significant differences. RESULT(S): Normozoospermic smokers had significantly higher abnormalities than their nonsmoking counterparts. Sperm histone replacement abnormalities were found to be closely correlated with sperm motility, viability, concentration, counts, and cotinine levels. The ratios of protamine 1 to protamine 2 mRNA expression significantly increased in heavy smokers and in TM3 cells treated with cigarette smoke condensate. CONCLUSION(S): Smoking is strongly associated with abnormalities in histone-to-protamine transition and with alteration of protamine mRNA expression in human sperm.


Assuntos
Histonas/metabolismo , Protaminas/metabolismo , Fumar/efeitos adversos , Fumar/metabolismo , Espermatozoides/anormalidades , Espermatozoides/metabolismo , Adulto , Animais , Células Cultivadas , Humanos , Masculino , Camundongos , RNA Mensageiro/metabolismo , Sêmen/metabolismo , Motilidade dos Espermatozoides/fisiologia
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