ABSTRACT
Different formulations of foaming polyurethane grout offer controlled expansion rates. This is crucial for precision in filling voids without exerting excessive pressure on surrounding structures, which could potentially cause damage. This study focuses on the impact of composition on the expansion performance of tailor-made polyurethane grouting materials. Initially, multiple unknown chemical reaction kinetic parameters were identified by combining free expansion tests, which involved measuring density and temperature changes, with the particle swarm optimization algorithm. A numerical simulation, integrating chemical kinetic models and fluid flow equations, was established to replicate the free expansion process of polyurethane grout in a cup, aligning with our experimental results. Subsequently, we analyzed the polymerization process of polyurethane grout with varying compositions to determine the effect of composition ratios on grout expansion. Our findings reveal that the expansion ratio of foaming polyurethane is predominantly influenced by the concentrations of physical and chemical foaming agents, followed by isocyanate concentration. Polyol, in contrast, exerts a relatively minor influence. Furthermore, the solubility of the physical foaming agent in the grout determines both its maximum allowable concentration and its maximum contribution to volume increase. This study provides valuable insights for the design and selection of polyurethane grout components tailored to diverse applications.
ABSTRACT
OBJECTIVE: To investigate the occurrence of anxiety and depression in elderly patients and to explore the effect of a psychological nursing intervention program based on the "Timing it Right" framework on the anxiety, depression, and self-efficacy among elderly patients. METHODS: 135 elderly patients admitted to our hospital were divided into two groups. The 69 patients in the experimental group underwent systematic psychological intervention, and the 66 patients in the control group were given only general psychological support. The Hospital Anxiety and Depression Scale (HADS) and the General Self Efficacy Scale (GSEs) scores were used to assess the effect of the psychological intervention program on the elderly patients. RESULTS: The psychological nursing intervention effect of the two groups after the intervention was improved compared with before the intervention (P < 0.05), and the Hospital Anxiety and Depression Scale (HADS) scores were lower in the experimental group than they were in the control group after the psychological intervention. The general self-efficacy scale scores of the experimental group were significantly improved after the intervention, and the scores in the experimental group were much higher than the scores in the control group after the intervention (P < 0.05). CONCLUSION: The incidences of anxiety and depression were higher in the elderly patients, and a psychological intervention program based on the "Timing it Right" framework can effectively reduce the negative emotions of anxiety and depression, and enhance the sense of self-efficacy.
