A simplified homogeneous approach for non-linear analysis of masonry infill panels under in-plane loads.

This paper aims to create a unified model that effectively combines continuous 2-dimensional elements and discrete components to capture the nonlinear characteristics and failure mechanisms of solid and perforated masonry infill panels. Given that masonry infill behavior is primarily influenced by shear deformations, an equivalent model is developed by using multiple small square panels arranged diagonally and interconnected by two-component springs, encompassing axial and shear behavior at their intersections. For the sake of simplicity, the divided panels are assumed to behave elastically, with plasticity concentrated only in the axial component of the connector springs. Plastic behavior in the boundary elements was considered to involve both flexural and shear plastic hinges to provide an accurate estimation of the entire infill panel's behavior. To validate this approach, the simplified model is benchmarked against eight experimental masonry infill panels surrounded by steel or reinforced concrete frames and with or without openings. The results including global behavior and crack pattern were compared with available numerical predictions based on finite element method from the literature in addition to experimental outcomes. Ultimately, this comparison demonstrated that the homogeneous model could effectively predict the non-linear lateral behavior of the panels and accurately forecast crack patterns. Additionally, the use of unidirectional non-linear springs and the appropriate arrangement of elastic panels significantly reduced both pre-processing and analysis time.

Comparative study of temperature effects on white sandstone and rockburst-like materials.

Rockburst physical model test, as one of the important means to study deep tunnel engineering, reflects the main influencing factors of rockburst into the model test through similar theory, so as to reveal the formation mechanism, influencing factors and evolution law of different types of rockburst in deep tunnels. In order to study the mechanical properties of white sandstone in deeply buried tunnels at high ground temperatures, materials suitable for conducting rockburst physical and mechanical tests were developed on the basis of the Daqian Shi Ling tunnel project, and similar material ratios were preferentially selected on the basis of white sandstone. Judged by the rock burst propensity, similar materials with low strength and high brittle characteristics, can better simulate the characteristics of white sandstone, and all show a strong propensity to rock burst, is the ideal rock burst similar materials. Uniaxial compressive tests were conducted on similar materials and the original rock at different temperatures, and comparative analysis was performed. Through the study of stress, displacement and modulus of elasticity, it was concluded that the compressive strength of similar materials gradually increased with temperature in the range of 20-100°C, and the vertical displacement at peak strength decreased with increasing temperature. The damage forms of white sandstone and similar materials at different temperatures were comparatively analyzed, and it was obtained that the damage forms of white sandstone and similar materials were basically the same, with a few specimens showing tensile and shear damage, and most specimens showing the form of combined tensile and shear damage. The study of rock burst similar materials and the development of the failure characteristics of rock burst under the action of thermal coupling are of great significance to the mechanism of rock burst generation and prediction.

In Situ Combustion Synthesis of Gr/h-BN Composites and Its Passive Heat Dissipation Application.

To enhance the infrared radiation efficiency and the heat transfer performance simultaneously, graphene (Gr) was synthesized in situ on hexagonal boron nitride (h-BN) to prepare Gr/h-BN composites by a scalable combustion synthesis in CO2 atmosphere using Mg as sacrificial solder. The synthesized Gr/h-BN composites were added in polydimethylsiloxane polymer to prepare composite coatings, which show an infrared emissivity greater than 0.95 and a through-plane thermal conductivity up to 2.584 W·m-1·K-1. When functioning on an Al heatsink, such a composite coating can reduce the temperature by as much as 21.7 °C. Meanwhile, the composite coating exhibits superior adhesion on the Al substrate. Therefore, Gr/h-BN composite coatings with noteworthy infrared radiation and thermal conductivity are expected to be a promising candidate for heat dissipation applications.

Effects of grape seed proanthocyanidins on the expression of inflammatory mediators in gingival epithelial cells.

OBJECTIVES: This study aims to determine the effect of grape seed proanthocyanidin (GSP) pretreatment on lipopolysaccharide (LPS)-induced inflammation of human gingival epithelial cells (HGECs). METHODS: HGECs were cultivated with different concentrations of GSPs (0, 1, 5, 10, 20, 40, 60, 80, 100 µg·mL-1) for 6, 12, 24, and 48 h. CCK-8 was used to detect the proliferation activity of HGECs. HGECs were treated with different concentrations of GSPs (0, 10, 20, and 40 µg·mL-1) for 24 h and then cultured with 1.0 µg·mL-1 LPS. Enzyme-linked immunosorbent assay (ELISA) was used to detect the expression levels of pro-inflammatory cytokine tumor necrosis factor-α (TNF-α), interleukin (IL)-1ß, and IL-6 and anti-inflammatory cytokines IL-4, IL-10, and transforming growth factor-ß (TGF-ß). Quantitative real-time polymerase chain reaction (QRT-PCR) was used to detect the mRNA expression levels of TNF-α, IL-1ß, IL-6, IL-4, IL-10, and TGF-ß. RESULTS: When the GSP concentration was 0-40 µg·mL-1, the cell proliferation had no significant difference. When the action time reached 24 h, the cell proliferation was the highest. The results of ELISA and QRT-PCR showed that 10, 20, and 40 µg·mL-1 GSPS decreased the expression levels of TNF-α, IL-1ß, and IL-6 (P<0.05) and increased the expression levels of IL-4, IL-10, and TGF-ß compared with 0 µg·mL-1 GSPS (P<0.05). CONCLUSIONS: GSPS (0-40 µg·mL-1) has no significant effect on the proliferation activity of HGECs. Pretreatment with GSPS can inhibit the expression of pro-inflammatory factors and enhance the expression of anti-inflammatory factors. Hence, GSPS has a certain preventive effect on the resistance of HGECs to the stimulation of endotoxin.