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Mass concrete structures are prone to suffer temperature destruction during construction and operation because of their own mechanical properties and the role of cement hydration; therefore, the law of temperature field and temperature stress changes is crucial. This paper is based on the heat conduction theory and contact friction element theory under general external load. The heat conduction matrix, node thermal load vector, equivalent stiffness-constraint matrix and equivalent load vector of the contact friction element are each added to the whole heat conduction matrix, thermal load vector and total stiffness matrix, and the total load vector according to the finite element integration rule to establish the thermal-stress calculation model of the contact friction element. Combined with the Qi River inverted siphon project, this paper analyzed the temperature field and temperature stress using the three-dimensional finite element method, considering the changes of concrete thermodynamic parameters with age and the outside air temperature and other conditions, and obtained the distribution and variation in temperature field and temperature stress during the construction of an inverted siphon. The research results are of great significance for temperature control and crack prevention of inverted siphon structures. The thermal-stress calculation model of the contact friction element overcomes the limitations that it is difficult to use the current contact surface model to perform the temperature field simulation and further improves the application of the contact friction element model in the simulation of the temperature field and the temperature stress of mass concrete.

5034 Background: KEYNOTE-427 (NCT02853344), a single-arm, open-label, phase 2 study, showed antitumor activity with first-line pembro monotherapy in nccRCC (cohort B). Studies of RCC and immune-oncology have shown that depth of tumor response may correlate with long-term benefit. We present the association between depth of response and OS plus updated efficacy and safety data in cohort B. Methods: Pts with histologically confirmed nccRCC, who did not receive prior systemic therapy, and who have measurable disease (RECIST v1.1) received pembro 200 mg IV Q3W for 2 y or until progressive disease, unacceptable toxicity, or withdrawal. End points were ORR (primary), DOR, and PFS (RECIST v1.1); OS; and safety. Association between depth of response, defined as maximum reduction from baseline in sum of target lesions, and OS was evaluated using a Cox proportional hazards model with target lesion reduction group as time-varying covariate. Results: Of 165 pts, 72% had papillary histology, 13% had chromophobe histology, and 16% were unclassified. Median time from enrollment to data cutoff was 18.7 mo (range, 9.9-26.0). ORR was 26.1% (95% CI, 19.5-33.5; 10 CRs, 33 PRs). Median (range) DOR was 15.3 mo (2.8-21.0+); 57.3% had DOR ≥12 mo. At 18-mo, PFS rate was 18.9% and OS rate was 67.0%. Most pts (58.8%) had some reduction in target lesions. Pts with a > 30% reduction in target lesions had an increased probability of survival (Table). ORR (95% CI) was similar for papillary (28.0% [20.1-37.0]) and unclassified (30.8% [14.3-51.8]) histology but lower for chromophobe (9.5% [1.2-30.4]). OS rates at 18 mo were 70.8%, 66.7%, and 50.0 in the papillary, chromophobe, and unclassified groups, respectively. Treatment-related AEs (TRAEs) occurred in 67.9% of all pts, primarily pruritus (19%), hypothyroidism (14%), and fatigue (14%). Grade 3-5 TRAEs occurred in 14% of pts; 2 pts died of TRAEs (pneumonia and cardiac arrest). Conclusions: First-line pembro monotherapy continued to show antitumor activity in nccRCC with no new safety concerns. In general, for pts who had greater reductions in target lesions, the trend was toward improved OS; pts with reduction of tumor burden ≥80% had comparable long term outcomes to those who achieved a RECIST 1.1 defined CR. Clinical trial information: NCT02853344 . [Table: see text]