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A novel layered magnesium phosphate (MgP) was synthesised from a MgO−P2O5‐choline chloride‐oxalic acid dihydrate system using an ionothermal approach. Single crystal samples of MgP were obtained following introduction of diethylamine (DEA) to the reaction system. Its structure revealed that both the layer and the sheets contained Mg octahedra. Interestingly, adding the layered material to lithium grease resulted in superior lubrication with higher load‐carrying, anti‐wear and friction reduction capacities compared with the typical lubricant MoS2; the PB value of base grease was increased from 353 to 1078 and 549 N, the wear scar diameter was decreased from 0.50 to 0.34 and 0.46 mm, and the friction coefficient was decreased from 0.082 to 0.056 and 0.075, respectively. We also discuss the lubrication mechanism of layered materials based on the crystal structure and resource endowment. The findings could assist the development of new high‐efficiency solid lubricants. [ABSTRACT FROM AUTHOR]

BackgroundSince the COVID-19 outbreak was first reported, considerable attention has been drawn to mental health problems among college students. ObjectiveWe aimed to estimate the prevalence of anxiety and depressive symptoms among college students in different geographical areas of China during the early stage of the COVID-19 outbreak. MethodsA nationwide cross-sectional survey was conducted among Chinese college students of 16 provinces or municipalities from February 4 to 12, 2020. A web-based survey was adopted to collect information from these college students, including demographics, perceived risk of infection, attitudes toward the epidemic and its control, and mental health status. Anxiety symptoms were assessed using the Generalized Anxiety Disorder scale, and depressive symptoms were assessed using the Patient Health Questionnaire. Chi-square test was used to compare the percentage of perceived risk of infection and attitude toward COVID-19 among college students in different geographic locations. Binary logistic models were used to identify associations between geographic locations and mental health problems after controlling for covariates. ResultsA total of 11,787 participants were analyzed in this study (response rate: 79.7%). The prevalence of anxiety and depressive symptoms among college students was 17.8% (95% CI 17.1%-18.5%) and 25.9% (95% CI 25.1%-26.7%), respectively. After controlling for covariates, current residence area in Wuhan city was found to have a positive association with anxiety symptoms (odds ratio [OR] 1.37, 95% CI 1.11-1.68) and depressive symptoms (OR 1.32, 95% CI 1.09-1.59). Similarly, college location in Wuhan city was found to have a positive association with anxiety symptoms (OR 1.20, 95% CI 1.07-1.35) and depressive symptoms (OR 1.22, 95% CI 1.10-1.36). History of residence in or travel to Wuhan city in the past month was also positively associated with anxiety symptoms (OR 1.62, 95% CI 1.46-1.80) and depressive symptoms (OR 1.48, 95% CI 1.35-1.63). Furthermore, the perceived risk of COVID-19 was higher among students whose college location and current residence area were in Wuhan city, and it was positively associated with anxiety and depressive symptoms. ConclusionsDuring the COVID-19 pandemic, mental health problems among Chinese college students were widespread and geographically diverse. Our study results provide further insight for policymakers to develop targeted intervention strategies.

A novel layered magnesium phosphate (MgP) was synthesised from a MgO-P 2 O 5 -choline chloride-oxalic acid dihydrate system using an ionothermal approach. Single crystal samples of MgP were obtained following introduction of diethylamine (DEA) to the reaction system. Its structure revealed that both the layer and the sheets contained Mg octahedra. Interestingly, adding the layered material to lithium grease resulted in superior lubrication with higher load-carrying, anti-wear and friction reduction capacities compared with the typical lubricant MoS 2 ; the P B value of base grease was increased from 353 to 1078 and 549 N, the wear scar diameter was decreased from 0.50 to 0.34 and 0.46 mm, and the friction coefficient was decreased from 0.082 to 0.056 and 0.075, respectively. We also discuss the lubrication mechanism of layered materials based on the crystal structure and resource endowment. The findings could assist the development of new high-efficiency solid lubricants., (© 2023 Wiley-VCH GmbH.)

In Li-ion batteries, the phase transition usually determines the electrochemical kinetics of some two-phase electrode materials, and it can be adopted to excellently interpret the memory effect of Li-ion batteries, therefore the size dependence of phase transition was expected to affect the memory effect significantly. In this work, we investigated the memory effect and phase transition of olivine LiFePO 4 in Li-ion batteries. Through electrochemical measurements, we found that the memory effect of LiFePO 4 was dependent on the particle size, especially after a long-time relaxation. By using the in situ X-ray diffraction, we found that the phase transition of nano-LiFePO 4 was ahead of the charging and discharging processes, while it took place concurrently or later for micro-LiFePO 4 , which might be attributed to the high-specific two-phase boundary of nano-LiFePO 4 . Furthermore, the phase-transition diagram was adopted to interpret the size-dependent memory effect schematically. Notably, it is the first time to report the phase transition ahead of (dis)charging for nano-LiFePO 4 , which is significant to understand the phase transition of two-phase electrode materials, as well as the relevant phenomena, such as the memory effect.