Structural analysis of the human C5a-C5aR1 complex using cryo-electron microscopy.

The complement system is a complex network of proteins that plays a crucial role in the innate immune response. One important component of this system is the C5a-C5aR1 complex, which is critical in the recruitment and activation of immune cells. In-depth investigation of the activation mechanism as well as biased signaling of the C5a-C5aR1 system will facilitate the elucidation of C5a-mediated pathophysiology. In this study, we determined the structure of C5a-C5aR1-Gi complex at a high resolution of 3 Å using cryo-electron microscopy (Cryo-EM). Our results revealed the binding site of C5a, which consists of a polar recognition region on the extracellular side and an amphipathic pocket within the transmembrane domain. Furthermore, we found that C5a binding induces conformational changes of C5aR1, which subsequently leads to the activation of G protein signaling pathways. Notably, a key residue (M265) located on transmembrane helix 6 (TM6) was identified to play a crucial role in regulating the recruitment of β-arrestin driven by C5a. This study provides more information about the structure and function of the human C5a-C5aR1 complex, which is essential for the proper functioning of the complement system. The findings of this study can also provide a foundation for the design of new pharmaceuticals targeting this receptor with bias or specificity

Fractal Analysis on the Mapping Relationship of Conductivity Properties in Porous Material

The mapping relationships between the conductivity properties are not only of great importance for understanding the transport phenomenon in porous material, but also benefit the prediction of transport parameters. Therefore, a fractal pore-scale model with capillary bundle is applied to study the fluid flow and heat conduction as well as gas diffusion through saturated porous material, and calculate the conductivity properties including effective permeability, thermal conductivity and diffusion coefficient. The results clearly show that the correlations between the conductivity properties of saturated porous material are prominent and depend on the way the pore structure changes. By comparing with available experimental results and 2D numerical simulation on Sierpinski carpet models, the proposed mapping relationships among transport properties are validated. The present mapping method provides a new window for understanding the transport processes through porous material, and sheds light on oil and gas resources, energy storage, carbon dioxide sequestration and storage as well as fuel cell etc

Fractal Analysis on the Mapping Relationship of Conductivity Properties in Porous Material

The mapping relationships between the conductivity properties are not only of great importance for understanding the transport phenomenon in porous material, but also benefit the prediction of transport parameters. Therefore, a fractal pore-scale model with capillary bundle is applied to study the fluid flow and heat conduction as well as gas diffusion through saturated porous material, and calculate the conductivity properties including effective permeability, thermal conductivity and diffusion coefficient. The results clearly show that the correlations between the conductivity properties of saturated porous material are prominent and depend on the way the pore structure changes. By comparing with available experimental results and 2D numerical simulation on Sierpinski carpet models, the proposed mapping relationships among transport properties are validated. The present mapping method provides a new window for understanding the transport processes through porous material, and sheds light on oil and gas resources, energy storage, carbon dioxide sequestration and storage as well as fuel cell etc

Extending the Behavioral Geography within the Context of Forest Restoration: Research on the Geographical Behaviors of Northern-Migrating Asian Elephants (<i>Elephas maximus</i>) in Southwest China

In 2021, the northward migration of Asian elephants in southwestern China’s Yunnan Province attracted significant public attention. Exploring the behavior of Asian elephants will help to better protect this endangered species and further realize the harmonious coexistence of humans and elephants. Based on the news texts regarding the northward migration of Asian elephants, this study used network text analysis, social network analysis, and grounded theoretical research methods to explore the behavioral characteristics and internal motivations of Asian elephants during their northward migration. The results indicate that: (1) during the northward migration of Asian elephants, moving and foraging are their most frequent behaviors, and foraging may be the chief purpose of the migration. (2) Different behaviors of Asian elephants hide their behavioral choice preferences, including environmental, time, and behavioral preferences. During the migration, Asian elephants mostly move in low-altitude areas, often foraging or migrating around farmland in the afternoon or at night, returning to the mountains to rest in the early morning. Corn, rice, and other crops are their primary food; the change in their eating habits is influenced by the lack of herbs and woody plants inside the protected area. (3) The northward migration behavior of elephant herds is influenced by various factors, such as elephant population expansion, habitat change, and species migration characteristics, and the relationship between conservation and development needs to be balanced

Performance evaluation for retrieving aerosol optical depth from the Directional Polarimetric Camera (DPC) based on the GRASP algorithm

International audienceAerosol spatial distribution obtained from satellite sensors is critical for understanding regional aerosol environments, anthropogenic aerosol emissions, and global climate change. The Directional Polarimetric Camera (DPC) is the first generation of multi-angle polarized sensor developed by China. It is on-board the GaoFen-5 satellite, running in 705 km sun-synchronous orbit with a 13:30 LT (local time) ascending node. The sensor has three polarized channels at 490, 670, and 865 nm and ∼ 9 viewing angles, mainly used for observing aerosols. The spatial resolution is ∼ 3.3 km at nadir, and global coverage is ∼ 2 d. In this study, the performance of aerosol optical depth (AOD) retrievals from the DPC/GaoFen-5 using the Generalized Retrieval of Atmosphere and Surface Properties (GRASP) algorithm were evaluated on a global basis for the first time. The results showed that the DPC GRASP/Model scheme, which used several forms of aerosol-type mixing, achieved good performance. By comparing with Aerosol Robotic Network (AERONET) observations, the correlation coefficient (R), root-mean-square error (RMSE), and expected error (EE%, ± (0.05+0.15×AOD)) were 0.9007 %, 0.0662 %, and 82.54 %, respectively. The scattering angle, number of averaged pixels, length of time steps, and radiative and polarized fitting residuals showed impacts on the results of AOD retrieval in the DPC GRASP/Model scheme. From the most AERONET sites, the R and EE% were larger than ∼ 0.9 % and ∼ 80%. Compared with Moderate resolution Imaging Spectroradiometer (MODIS) products, the spatial and temporal variations of aerosol could be caught by the DPC with the GRASP/Model scheme, showing a good performance. However, values of AOD were also underestimated by DPC, probably due to an overly strict cloud mask. The above findings validated the ability of the DPC sensor to monitor aerosols. It should contribute to the development of aerosol parameter retrieval from multi-angle polarized sensors in the future