Herein, a porous oil-containing material with hierarchical pore structure was successfully prepared through microtexturing large pores on the surface of porous polyimide (PPI) with single-level small pores. Compared to the conventional oil-containing material, the hierarchically porous oil-containing material exhibited high oil-content, and retained excellent mechanical properties and high oil-retention because of the synergistic effects of large pores and small pores. Furthermore, the lubricant stored in the hierarchically porous polyimide could release to the interface under thermal-and-mechano-stimuli, and the released lubricant could be reabsorbed into the hierarchically porous polyimide via the capillary-force offered by the porous channel. Based on the high oil-content and recyclable oil release/reabsorption, the hierarchically porous oil-containing polyimide exhibited excellent lubrication performance (coefficient of friction was 0.057). Furthermore, the composite could perform 1,069 cycles of smart lubrication (1 h per cycle), which significantly extended the service life of the hierarchically porous oil-containing smart lubrication material.

For the tribological properties of nanoparticle-modified PTFE, a more comprehensive study has been conducted, but there is still some room for research on tribology behavior, tribofilm formation and structure evolution of polytetrafluoroethylene (PTFE) filled with α-Al₂O₃ and SiO₂ nanoparticles during sliding against steel counterparts under different loads. At the same time, it establishes the linkage and mechanism between the maintenance of mechanical strength and the tribological application of polymers in service and provides corresponding scientific data and theoretical guidance for the long-lasting application of polymer lubrication materials. It is found that both composites exhibit good wear resistance across the pressure of 1 MPa to 10 MPa, with the α-Al₂O₃/PTFE composite demonstrating better performance stability compared to the SiO₂/PTFE composite. The high wear resistance is attributed to the formation of tribofilms at the friction interface. For the α-Al₂O₃/PTFE, an island-like tribofilm is formed with a thickness ranging from 100 to 200 nm, while the tribofilm of the SiO₂/PTFE composite is thinner, measuring approximately 50 to 100 nm, and manifests a striped pattern. The chemical composition, both at the surface and subsurface levels, as well as the morphology of the tribofilms, were studied using FTIR spectrometry, X-ray photoelectron spectroscopy (XPS), and FIB-TEM. It is found that the difference in thickness and microstructure of the tribofilms for the two composites is mainly due to the tribochemistry of the nanoparticles. The α-Al₂O₃ nanoparticle plays a “cohesion” role during the formation of the tribofilm, which facilitates the formation of a thicker, more uniform, and stronger adhered tribofilm on the metallic counterpart, making it more robust against higher shear stress.

Background: Certain studies have indicated a link between obstructive sleep apnea and insulin resistance in specific populations. To gain more clarity, extensive research involving a broad sample of the overall population is essential. The primary objective of this study was to investigate this correlation by utilizing data from the National Health and Nutrition Examination Survey database. Methods: The analysis incorporated data from the National Health and Nutrition Examination Survey database spanning the time periods from 2005 to 2008 and from 2015 to 2018, with a focus on American adults aged 18 years and older after applying weight adjustments. Key variables such as obstructive sleep apnea, triglyceride glucose index, and various confounding factors were considered. A generalized linear logistic regression model was used to investigate the association between obstructive sleep apnea and the triglyceride glucose index, with additional exploration of the consistency of the results through hierarchical analysis and other techniques. Results: The study included participants aged between 18 and 90 years, with an average age of 46.75 years. Among the total sample, 50.76% were male. The triglyceride glucose index demonstrated a diagnostic capability for obstructive sleep apnea, with an AUC of 0.701 (95% CI: 0.6619–0.688). According to the fully adjusted model, individuals in the fourth quartile of the triglyceride glucose index showed an increased likelihood of having obstructive sleep apnea compared to those in the first quartile (OR: 1.45; 95% CI: 1.02–2.06; P < 0.05). Subgroup analysis indicated that male sex (OR: 2.09; 95% CI: 1.76–2.45; P < 0.05), younger age (OR: 2.83; 95% CI: 2.02–3.96; P < 0.05), white ethnicity (OR: 2.29; 95% CI: 1.93–2.73; P < 0.05), and obesity (OR: 1.54; 95% CI: 1.28–1.85; P < 0.05) were correlated with an elevated risk of OSA. Conclusions: This study demonstrated a strong association between an elevated TG index and OSA. Additionally, the triglyceride glucose index could serve as an independent predictor of obstructive sleep apnea.

In this study, cotton fabric-reinforced phenolic resin (CPF) composites were modified by adding four two-dimensional fillers: graphitic carbon nitride (g-C₃N₄), graphite (Gr), molybdenum disulfide (MoS₂), and hexagonal boron nitride (h-BN). The tribological properties of these modified materials were investigated under dry friction and water lubrication conditions. The CPF/Gr composite exhibits significantly better tribological performance than the other three filler-modified CPF composites under dry friction, with a 24% reduction in friction coefficient and a 78% reduction in wear rate compared to the unmodified CPF composite. Under water lubrication conditions, all four fillers did not significantly alter the friction coefficient of the CPF composites. However, except for an excessive amount of Gr, the other three fillers can reduce the wear rate. Particularly in the case of 10% MoS₂ content, the wear rate decreased by 56%. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed for the analysis of the morphology and composition of the transfer films. Additionally, molecular dynamics (MD) simulations were conducted to investigate the adsorption effects of CPF/Gr and CPF/MoS₂ composites on the counterpart surface under both dry friction and water lubrication conditions. The difference in the adsorption capacity of CPF/Gr and CPF/MoS₂ composites on the counterpart, as well as the resulting formation of transfer films, accounts for the variation in tribological behavior between CPF/Gr and CPF/MoS₂ composites. By combining the lubrication properties of MoS₂ and Gr under dry friction and water lubrication conditions and using them as co-fillers, we can achieve a synergistic lubrication effect.