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Over the past few years, due to the rapid development of machine learning (ML) models for weather forecasting, state-of-the-art ML models have shown superior performance compared to the European Centre for Medium-Range Weather Forecasts (ECMWF)'s high-resolution forecast (HRES) in 10-day forecasts at a spatial resolution of 0.25 degree. However, the challenge remains to perform comparably to the ECMWF ensemble mean (EM) in 15-day forecasts. Previous studies have demonstrated the importance of mitigating the accumulation of forecast errors for effective long-term forecasts. Despite numerous efforts to reduce accumulation errors, including autoregressive multi-time step loss, using a single model is found to be insufficient to achieve optimal performance in both short and long lead times. Therefore, we present FuXi, a cascaded ML weather forecasting system that provides 15-day global forecasts with a temporal resolution of 6 hours and a spatial resolution of 0.25 degree. FuXi is developed using 39 years of the ECMWF ERA5 reanalysis dataset. The performance evaluation, based on latitude-weighted root mean square error (RMSE) and anomaly correlation coefficient (ACC), demonstrates that FuXi has comparable forecast performance to ECMWF EM in 15-day forecasts, making FuXi the first ML-based weather forecasting system to accomplish this achievement.

Although research on the osteal signaling pathway has progressed, understanding of gut microbial-dependent signaling pathways for metabolic and immune bone homeostasis remains elusive. In recent years, the study of gut microbiota has shed light on our understanding of bone homeostasis. Here, we review microbiota-mediated gut-bone crosstalk via bone morphogenetic protein/SMADs, Wnt and OPG/receptor activator of nuclear factor-kappa B ligand signaling pathways in direct (translocation) and indirect (metabolite) manners. The mechanisms underlying gut microbiota involvement in these signaling pathways are relevant in immune responses, secretion of hormones, fate of osteoblasts and osteoclasts and absorption of calcium. Collectively, we propose a signaling network for maintaining a dynamic homeostasis between the skeletal system and the gut ecosystem. Additionally, the role of gut microbial improvement by dietary intervention in osteal signaling pathways has also been elucidated. This review provides unique resources from the gut microbial perspective for the discovery of new strategies for further improving treatment of bone diseases by increasing the abundance of targeted gut microbiota.

A new-type multiple-source heat pump cycle with two-stage compression was established on the basis of the problems of similarly existing heat pumps. The equivalent temperature levels of typical evaporators are applied to the different heat sources of the proposed cycle, and the high-temperature heat sources are shown to enhance vapor injection. Then, the mathematical model and prototype are developed, and the results from experimental simulation and validation showed that the solar collector can improve the heating performance of the proposed heat pump system. In the middle-temperature heating period, the outdoor temperature is less than −25°C, and the average coefficient of performance (COP) value of the proposed heat pump was 4.2, which was greater than the COPs of conventional ground source heat pumps.

Recently, energy storage system (ESS) with carbon dioxide (CO2) as working fluid has been proposed as a new method to deal with the application restrictions of Compressed Air Energy Storage (CAES) technology, such as dependence on geological formations and low energy storage density. A novel ESS named as Compressed CO2 Energy Storage (CCES) based on transcritical CO2 Brayton cycle is presented in this paper. The working principle of CCES system is introduced and thermodynamic model is established to assess the system performance. Parametric analysis is carried out to study the effect of some key parameters on system performance. Results show that the increase of turbine efficiency is more favorable for system optimization and the effect of minimum pressures on system performance is more significant compared with maximum pressures. A simple comparison of CCES system, liquid CO2 system and Advanced Adiabatic Compressed Air Energy Storage (AA-CAES) system is conducted. It is shown that the system efficiency of CCES is lower than that of AA-CAES system but 4.05% higher than that of liquid CO2 system, while the energy density of CCES system is 2.8 times the value of AA-CAES system, which makes CCES a novel ESS with potential application.

With increasing development of geographical information technology, the means and methods of geography class teaching are developing as well. This paper aims at the study how Google Earth assists us with geographical teaching in middle school. Firstly, this paper makes a brief introduction of the function of Google Earth as well as their advantages applied in geography class teaching. Then, the methods of applying Google Earth to geography educational content in middle school are described. Finally, taking the Yangzi River in junior textbook as an example, the applying process of the mentioned above is achieved.