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Grasslands support a rich diversity that plays a pivotal role in ecological balance, carbon sequestration, and climate regulation. Grassland ecosystems are facing a loss of biodiversity and a decline in soil function due to precipitation variations caused by climate change. However, variations in grassland species diversity are not clearly known, especially under the combined effects of precipitation and grazing. Based on a 5‐year split‐plot experiment with two grazing regimes (i.e., moderate grazing and grazing prohibition) along with three precipitation controls (ambient precipitation and ±50% precipitation) in Inner Mongolian grasslands, we researched the response of precipitation variability and grazing prohibition to vegetation diversity indices and investigated the response of vegetation community composition and biomass to these factors. Five years results showed that increasing precipitation resulted in a significant increase in the coverage of perennial forbs, annual and biennial plants, and Gramineae. Grazing prohibition and increased precipitation significantly increased biomass and species richness compared to all other treatment combinations. Interestingly, grazing exclusion significantly reduced the percentage of Amaryllidaceae, especially in the presence of altered precipitation. The vegetation community composition of a typical grassland was correlated with soil volumetric water content (VWC), bulk density (SBD) and pH, soil organic carbon (SOC), and total nitrogen (TN). VWC, SBD, and TN were found to be the most significant factors affecting vegetation diversity under grazing. Partial canonical ordination revealed that soil moisture, soil bulk density, and SOC had the most significant correlation with vegetation diversity under both grazing prohibition and increased precipitation treatment conditions. These results suggested that alterations in precipitation can change the species composition and ecosystem function of plant communities, leading to a close relationship between species diversity and soil properties. Our results underline the importance of species diversity for soil characteristics and environmental factors in a typical Eurasian steppe ecosystem. [ABSTRACT FROM AUTHOR]

1,4-Butanediol (BDO) is an important chemical raw material for a series of high-value-added products. And the ethynylation of formaldehyde is the key step for the production of BDO by the Reppe process. However, little work has been done to reveal the reaction mechanism. In this work, the reaction mechanism for the ethynylation of formaldehyde process on copper-terminated Cu2O(100) surfaces was investigated with density functional theory (DFT). The reaction network of the ethynylation of formaldehyde was constructed first and the adsorption properties of the related species were calculated. Then the energy barrier and reaction energy of the related reactions and the geometric configuration were calculated. It is a consecutive reaction including two processes. For the propargyl alcohol (PA) formation process, the most favorable pathway is the direct addition of acetylene to formaldehyde followed by a hydrogen transfer reaction. And the rate control step is the hydrogen transfer reaction with an energy barrier of 1.43 eV. For the 1,4-butynediol (BYD) formation process, the most competitive pathway is the addition of PA to CH2OH, including formaldehyde hydrogenation to form CH2OH, coupling addition, and dehydrogenation reaction. The rate control step of this pathway is the dehydrogenation reaction with an energy barrier of 1.51 eV. [ABSTRACT FROM AUTHOR]

Soil temperature (Ts) and hydrothermal processes are determinants of grassland vegetation growth in arid and semi‐arid area. Implementation of grazing exclusion in grazed grasslands is bound to change the state of vegetation and soil, with consequent effects on Ts and hydrothermal relations. To investigate the differences in the response of Ts and hydrothermal variation to different durations of grazing exclusion, this study conducted a 4‐year fencing exclusion experiment from 2019 to 2022 in Eritu Ranch, Xilingole League, Inner Mongolia. Soil water content (SWC), Ts and precipitation were continuously observed under grazing and different years of grazing exclusion. Statistical correlation analysis was used to assess changes in Ts and moisture after 1 and 4 years of grazing exclusion, and to investigate the differences in Ts response to the same rainfall events and changes during freeze–thaw periods under different grazing exclusion durations. The results show that after 1 year of grazing exclusion, the summer surface Ts decreased by 0.23°C, while the winter surface Ts increased by 0.55°C. After 4 years of grazing exclusion, the summer surface Ts decreased further by 1.18°C, while the winter surface Ts decreased by 0.39°C. This suggests that grazing exclusion has differential effects on seasonal Ts dynamics. Compared with grazing grassland (GG), Ts in grazing exclusion grassland (GEG) shows less response to rainfall. During the freeze–thaw period, soil moisture in GEG is more sensitive to precipitation than in GG. Regression analysis revealed that the correlation between Ts and moisture during the freezing phase was weaker in GEG than in GG. Furthermore, the difference in correlation between 1 and 4 years of grazing exclusion was smaller than expected. During the melting phase, the relationship between Ts and SWC in the soil differed less after 1 year of grazing exclusion compared with GG. However, after 4 years of grazing exclusion, the correlation between Ts and SWC was generally greater in the GEG, suggesting that grazing exclusion may lead to changes in soil moisture dynamics that affect Ts. The results indicate that after 4 years of grazing exclusion, Ts and SWC conditions are better than those after 1 year of grazing exclusion. These findings have significant implications for understanding the impact of grazing‐induced soil warming and drying processes on ecosystems. [ABSTRACT FROM AUTHOR]

Early diagnosis of acute myocardial infarction (AMI) can significantly reduce mortality, which can be achieved by the highly sensitive detection of AMI-specific cardiac troponin I (cTnI) biomarkers. Herein a highly sensitive and portable photoelectrochemical (PEC) immunoassay for the detection of cTnI was innovatively fabricated based on an efficient photocurrent response of Cu2O coupling with a split-type enzymatic biocatalytic precipitation reaction with a digital multimeter readout. Initially, Cu2O cubic nanomaterials with a good photocurrent response were obtained by facile green room temperature synthesis and dropped on fluorine-doped tin oxide (FTO) plates as photoactive materials (Cu2O/FTO). In the presence of target cTnI, horseradish peroxidase (HRP) on the detection antibody catalyzes the substrate 4-chloro1-naphthol (4-CN) to produce insoluble precipitates of benzo-4-chlorohexadienone (4-CD) on Cu2O/FTO with the assistance of H2O2, resulting in a decrease in the photocurrent of the Cu2O/FTO electrode. To make the whole inspection process more concise and efficient, we used a flashlight and a digital multimeter as the excitation light source and reading device for the PEC sensing system, respectively. Under the optimal conditions of immunoreaction time, pH, and loading, the photocurrent of Cu2O/FTO decreased with increasing target cTnI concentration with a limit of detection (LOD) of 4.7 pg mL−1 in the operating range of 0.01–10 ng mL−1. It is of interest that the developed portable PEC immunoassay is also capable of detecting cTnI in human serum samples with acceptable accuracy compared to the reference cTnI enzyme-linked immunosorbent assay (ELISA) method while maintaining portability and sensitivity. [ABSTRACT FROM AUTHOR]

1,4-Butanediol (BDO) is an important chemical raw material for a series of high-value-added products. And the ethynylation of formaldehyde is the key step for the production of BDO by the Reppe process. However, little work has been done to reveal the reaction mechanism. In this work, the reaction mechanism for the ethynylation of formaldehyde process on copper-terminated Cu 2 O(100) surfaces was investigated with density functional theory (DFT). The reaction network of the ethynylation of formaldehyde was constructed first and the adsorption properties of the related species were calculated. Then the energy barrier and reaction energy of the related reactions and the geometric configuration were calculated. It is a consecutive reaction including two processes. For the propargyl alcohol (PA) formation process, the most favorable pathway is the direct addition of acetylene to formaldehyde followed by a hydrogen transfer reaction. And the rate control step is the hydrogen transfer reaction with an energy barrier of 1.43 eV. For the 1,4-butynediol (BYD) formation process, the most competitive pathway is the addition of PA to CH 2 OH, including formaldehyde hydrogenation to form CH 2 OH, coupling addition, and dehydrogenation reaction. The rate control step of this pathway is the dehydrogenation reaction with an energy barrier of 1.51 eV.