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Anthropogenic activities have substantially enhanced the loadings of reactive nitrogen (Nr) in the Earth system since pre-industrial times1,2, contributing to widespread eutrophication and air pollution3-6. Increased Nr can also influence global climate through a variety of effects on atmospheric and land processes but the cumulative net climate effect is yet to be unravelled. Here we show that anthropogenic Nr causes a net negative direct radiative forcing of -0.34 [-0.20, -0.50] W m-2 in the year 2019 relative to the year 1850. This net cooling effect is the result of increased aerosol loading, reduced methane lifetime and increased terrestrial carbon sequestration associated with increases in anthropogenic Nr, which are not offset by the warming effects of enhanced atmospheric nitrous oxide and ozone. Future predictions using three representative scenarios show that this cooling effect may be weakened primarily as a result of reduced aerosol loading and increased lifetime of methane, whereas in particular N2O-induced warming will probably continue to increase under all scenarios. Our results indicate that future reductions in anthropogenic Nr to achieve environmental protection goals need to be accompanied by enhanced efforts to reduce anthropogenic greenhouse gas emissions to achieve climate change mitigation in line with the Paris Agreement.

Nitrous oxide (N2O) is a greenhouse gas and stratospheric ozone-depleting substance with large and growing anthropogenic emissions. Previous studies identified the influx of N2O-depleted air from the stratosphere to partly cause the seasonality in tropospheric N2O (aN2O), but other contributions remain unclear. Here, we combine surface fluxes from eight land and four ocean models from phase 2 of the Nitrogen/N2O Model Intercomparison Project with tropospheric transport modeling to simulate aN2O at eight remote air sampling sites for modern and pre-industrial periods. Models show general agreement on the seasonal phasing of zonal-average N2O fluxes for most sites, but seasonal peak-to-peak amplitudes differ several-fold across models. The modeled seasonal amplitude of surface aN2O ranges from 0.25 to 0.80 ppb (interquartile ranges 21%–52% of median) for land, 0.14–0.25 ppb (17%–68%) for ocean, and 0.28–0.77 ppb (23%–52%) for combined flux contributions. The observed seasonal amplitude ranges from 0.34 to 1.08 ppb for these sites. The stratospheric contributions to aN2O, inferred by the difference between the surface-troposphere model and observations, show 16%–126% larger amplitudes and minima delayed by ∼1 month compared to Northern Hemisphere site observations. Land fluxes and their seasonal amplitude have increased since the pre-industrial era and are projected to grow further under anthropogenic activities. Our results demonstrate the increasing importance of land fluxes for aN2O seasonality. Considering the large model spread, in situ aN2O observations and atmospheric transport-chemistry models will provide opportunities for constraining terrestrial and oceanic biosphere models, critical for projecting carbon-nitrogen cycles under ongoing global warming.

Objective To investigate the effect of Enterococcus faecalis (E. faecalis) lipoteichoic acid (LTA) on the expression of the macrophage immune checkpoint-programmed cell death protein ligand 1 (PD-L1) and explore the possible regulatory mechanisms. Methods In vitro model was established by stimulating mouse monocyte macrophage cell line (RAW264.7) with different concentrations of E. faecalis LTA. PD-L1 expression and nuclear factor kappa-B (NF-κB) p65 phosphorylation level were detected using flow cytometry, quantitative real-time polymerase chain reaction (qRT-PCR), Western blot and cellular immunofluorescence. Macrophages were pretreated with the NF-κB signaling pathway inhibitor BAY 11-7082, then the expression of PD-L1 and p65 phosphorylation level were detected by the above methods. Results LTA induced PD-L1 expression in RAW264.7 cells, and p65 phosphorylation level increased (P

Currently, most research on recognizing unsafe behaviors of underground personnel focuses on improving precision through computer vision. However, underground areas are prone to occlusion, unstable lighting, and reflection, making it difficult to accurately recognize unsafe behaviors using computer vision technology alone. Especially, similar actions such as climbing ladders and holding ladders during climbing operations are easily confused during the recognition process, posing safety hazards. In order to solve the above problems, a multi-modal detection method for holding ladders in underground climbing operations is proposed. This method analyzes surveillance video data from two modalities: visual and audio. In terms of visual modality, the YOLOv8 model is used to detect the presence of ladder. If there is a ladder, the position coordinates of the ladder are obtained, and the video segment is put into the OpenPose algorithm for pose estimation to obtain the features of various skeletal joint points of the human body. These skeletal joint point sequences are then placed into improved spatial attention temporal graph convolutional networks(SAT-GCN) to obtain human action labels and their corresponding probabilities. In terms of audio modality, the PaddlePaddle automatic language recognition system is used to convert speech into text, and the bidirectional encoder representations from transformers (BERT) model is used to analyze and extract the features of text information, so as to obtain the text label and its corresponding probability. Finally, the information obtained from the visual and audio modalities is fused at the decision-making level to determine whether there is a dpersonnel holding ladders for underground climbing operations. The experimental results show that in action recognition based on skeleton data, the optimized SAT-GCN model improves the recognition precision of three types of actions: holding, climbing, and standing by 3.36%, 2.83%, and 10.71%, respectively. The multi-modal detection method has a higher recognition accuracy than the single modal method, reaching 98.29%.

Objective To explore the postmortem diffusion rule of Aconitum alkaloids and their metabolites in poisoned rabbits, and to provide a reference for identifying the antemortem poisoning or postmortem poisoning of Aconitum alkaloids. Methods Twenty-four rabbits were sacrificed by tracheal clamps. After 1 hour, the rabbits were administered with aconitine LD50 in decocting aconite root powder by intragastric administration. Then, they were placed supine and stored at 25 ℃. The biological samples from 3 randomly selected rabbits were collected including heart blood, peripheral blood, urine, heart, liver, spleen, lung and kidney tissues at 0 h, 4 h, 8 h, 12 h, 24 h, 48 h, 72 h and 96 h after intragastric administration, respectively. Aconitum alkaloids and their metabolites in the biological samples were analyzed by high performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS）. Results At 4 h after intragastric administration, Aconitum alkaloids and their metabolites could be detected in heart blood, peripheral blood and major organs, and the contents of them changed dynamically with the preservation time. The contents of Aconitum alkaloids and their metabolites were higher in the spleen, liver and lung, especially in the spleen which was closer to the stomach. The average mass fraction of benzoylmesaconine metabolized in rabbit spleen was the highest at 48 h after intragastric administration. In contrast, the contents of Aconitum alkaloids and their metabolites in kidney were all lower. Aconitum alkaloids and their metabolites were not detected in urine. Conclusion Aconitum alkaloids and their metabolites have postmortem diffusion in poisoned rabbits, diffusing from high-content organs （stomach） to other major organs and tissues as well as the heart blood. The main mechanism is the dispersion along the concentration gradient, while urine is not affected by postmortem diffusion, which can be used as the basis for the identification of antemortem and postmortem Aconitum alkaloids poisoning.

Hydrogels prepared by hydroxypropyl starch have better tensile properties than ordinary starch, but their mechanical properties are relatively poor. In this paper, effect of the heat-moisture treatment on the physical, chemical and the gel properties of hydroxypropyl starch was studied. Compared with the control group, the thermal stability of starch has been improved and the maintenance value decreased from 12.55 J/g to 6.58 J/g. The XRD analysis showed that the crystallicity of the strength from 30.4% to 19.6%. The double helix in strength was first destroyed by heat-moisture treatment. The peak viscosity of hydroxypropyl starch first rose to about 5 000 cp and then dropped to about 3 000 cp. The TPA and the rheological analysis showed that the hardness of the starch increased after the heat treatment of 223.51 g to 463.50 g and the storage elastic module increased, indicating that wet heat treatment improved the mechanical properties of the starch.

The Yangtze River basin is a typical region of the world that has a well-developed economy but is also greatly affected by multiple climate extremes. An improved understanding of future climate trends and associated exposures in this region is urgent needed to address socioeconomic risks. This research aims to quantify historical and future projected population exposure to precipitation extremes in the Yangtze basin using meteorological records and downscaled climate models. The study found that the hazard zone for precipitation extremes during baseline period was primarily located in the mid-lower Yangtze basin, particularly around the Poyang Lake watershed. Climate projections for 2050 indicate a further increase in the occurrence of precipitation extremes in this hazard zone, while a decrease in extreme events is detectable in the upper Yangtze basin under higher radiative forcing. Future socioeconomic scenarios suggest a tendency for population growth and migration towards the lower Yangtze basin, resulting in aggravated climate risks in megacities. Multi-model simulations indicate that population exposure to precipitation extremes in the lower Yangtze basin will increase by 9–22% around 2050, with both climate and population factors contributing positively. Shanghai, Changsha, Hangzhou, Ganzhou, and Huanggang are identified as hotspot cities facing the highest foreseeable risks of precipitation extremes in the Yangtze basin.