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Given that the existing drainage strengthening methods for underwater damaged piers are expensive, inefficient, and cause shipping traffic disruptions, an urgent need exists to explore undrained strengthening methods, such as the precast concrete segment assembly method (PCSAM). However, the PCSAM has certain limitations, including a considerable strength loss of filled concrete, poor accuracy, poor connection performance of the segment sleeves, etc. Hence, this study developed an improved PCSAM (IPCSAM) by adopting self-stressed anti-washout concrete (SSAWC) as the filling material and developing a lining concrete segment sleeve (LCSS) based on the design principle of shield tunnel lining segments. Subsequently, the seismic performance of the strengthened piers was investigated. First, nine 1/5-scale pier column specimens were designed by considering different influencing factors: the self-stress of the SSAWC, LCSS reinforcement ratio, and initial damage and length–diameter ratio of the pier column. These specimens were tested under low reversed cyclic loading. Second, an extended parameter analysis was performed based on the established numerical models consistent with the quasi-static test's parameter settings. Finally, a restoring force model of the strengthened piers, including the trilinear skeleton curve model and hysteresis curve model, was established based on the results of the quasi-static test and parameter analysis. The results indicated that the bearing capacity, ductility, and initial stiffness of the specimens strengthened using the IPCSAM increased by approximately 83.5–106.4%, 16.3–50.2%, and 83.9–177.3%, respectively, with the energy dissipation capacity also significantly improved. The self-stress of the SSAWC should not exceed 2.2 MPa, and the recommended ratio of the LCSS thickness to pier column diameter is 1/10. Additionally, the proposed restoring force model is highly accurate and applicable, able to provide a reference for the practical seismic strengthening design of piers. [ABSTRACT FROM AUTHOR]

Background and Aim: This study was designated to assess the diagnostic value of 99 Tc M -2-(2-methyl-5-nitro-1 H -imidazol-1-yl) ethyl dihydrogen phosphate ( 99 Tc M -MNLS) hypoxia imaging and its evaluation performance for radiotherapy efficacy in patients with non-small-cell lung cancer (NSCLC)., Patients and Methods: A total of 61 patients with NSCLC were selected for this study. All patients were injected with 99 Tc M -MNLS within 1 week prior to radiotherapy and they were injected with 99 Tc M -MNLS again 3 months after radiotherapy. Qualitative analysis along with semiquantitative analysis results were obtained from hypoxia imaging. Meanwhile, the effect of radiotherapy on patients with NSCLC was evaluated based on the solid tumor curative effect evaluation standard. Finally, SPSS 19.0 statistical software was implemented for statistical analysis., Results: There was no significant difference in age or sex between the NSCLC patient group and benign patient group ( P >0.05). 99 Tc M -MNLS was selectively concentrated in tumor tissues with a clear imaging in 24 hours. Results from both qualitative analysis and semiquantitative analysis indicated that the sensitivity and specificity of 99 Tc M -MNLS hypoxia imaging in diagnosing NSCLC were 93.8% and 84.6% and 72.9% and 100%, respectively. Moreover, the receiver operating characteristic curve provided evidence that 99 Tc M -MNLS hypoxia imaging was a powerful diagnostic tool in distinguishing malignant lung cancer from benign lesions. As suggested by 24-hour imaging, the tumor-to-normal ratio of patients in the 99 Tc M -MNLS high-intake group and low-intake group had a decline of 24.7% and 14.4% after radiotherapy, respectively. The decline in the tumor-to-normal ratio between the two dosage groups was significantly different ( P <0.05)., Conclusion: 99 Tc M -MNLS hypoxia imaging had reliable values in both diagnosing NSCLC and evaluating therapeutic effects of radiotherapy on patients with NSCLC., Competing Interests: The authors report no conflicts of interest in this work.