RESUMO
In engineering practice, similar surface insulation measures are typically applied to different parts of mass concrete surfaces. However, this can lead to cracking at the edges of the concrete surface or the wastage of insulation materials. In comparison to flat surfaces, the edges of mass concrete structures dissipate heat more rapidly, leading to more pronounced stress concentration phenomena. Therefore, reinforced insulation measures are necessary. To reduce energy consumption and enhance overall insulation effectiveness, it is essential to study the specific insulation requirements of both the flat surfaces and edges of concrete separately and implement targeted surface insulation measures. Taking the bridge abutment planned for pouring in Nanjing City as the research object, this study established a finite element model to explore the effects of different ambient temperatures and different surface heat dissipation coefficients on the early-age temperature and stress fields of different parts of the abutment's surface. Based on simulation results, reasonable heat dissipation coefficients that meet the requirements for crack prevention on both the structure's plane and edges under different ambient temperatures were obtained. The results indicate that under the same conditions, the reasonable heat dissipation coefficient at the edges was smaller than that on the flat surfaces, indicating the need for stronger insulation measures at the edges. Finally, mathematical models correlating ambient temperature with reasonable heat dissipation coefficients for the structure's plane and edges at these temperatures were established, with high data correlation and determination coefficients (R2) of 0.95 and 0.92. The mathematical models were validated, and the results from finite element calculations were found to be consistent with those from the mathematical models, validating the accuracy of the mathematical models. The conclusions drawn can provide references for the insulation of similar engineering concrete planes and edges.
RESUMO
To elucidate the impact mechanism of the interfacial characteristics of Calcium Silicate Hydrate gel (CSH)-Montmorillonite (MMT) at the nanoscale on the strength of cement-stabilized montmorillonite soil, this paper begins by examining the interfacial energy. Through Molecular Dynamics (MD) simulation methods, the energy at the MMT and CSH binding interface is quantitatively calculated, and the correlation between the interfacial energy and macroscopic strength is determined in conjunction with grey relational analysis. Finally, based on the characterization results from X-ray diffraction (XRD), the accuracy and sources of deviation in the MD simulation results are discussed. The study shows the CSH-MMT interfacial energy is composed of van der Waals forces, hydrogen bond energy, and electrostatic interactions, which are influenced by the migration of cations; there is a good consistency between the CSH-MMT interfacial energy and the unconfined compressive strength (UCS) of cement-stabilized soil (cemented soil), with the interfacial energy decreasing as the number of water molecules increases and first decreasing then increasing as the number of MMT layers grows; by adjusting the mix proportions, the magnitude of the CSH-MMT interfacial energy can be altered, thereby optimizing the strength of the cemented soil.
RESUMO
BACKGROUND: A few patients with ductal carcinoma in situ (DCIS) after breast conservative surgery would develop ipsilateral breast cancer recurrence (IBTR), either invasive or non-invasive. Study of accurate predictive biomarkers for IBTR risk are warranted. We analyzed the association of human epidermal growth factor receptor 2 (HER2) status with IBTR after conservative surgery. METHODS: We chose 213 cases of DCIS diagnosed between 2005 and 2010. Immunohistochemistry was performed for ER, PR, and HER2. The primary endpoint was IBTR. Kaplan-Meier plot was used for univariate survival analysis with log-rank test. Cox proportional hazards model was used for multivariate analysis. Hazard ratio (HR) and 95% confidence interval (CI) were calculated. RESULTS: With a median follow-up 80 months, there were 29 IBTR events. In univariate analysis, patients with high grade, ER-negative, and HER2-positive breast cancers tended to have an increased risk of IBTR. In multivariate analysis, grade III and HER2-positivity were independent predictive factors for IBTR. HER2-positive DCIS had a 2.6-time risk of recurrence compared with those with HER2-negative tumors (HR=2.60; 95% CI, 1.02-6.98; P=0.044). For HER2-equivocal cases, the HR was 1.59 (95% CI, 0.40-6.34; P=0.50) compared with HER2-negative cases. Moreover, annual recurrence pattern according to HER2 status showed that HER2-positive DCIS had a recurrence peak at 3-5 years (0.3% per annum) while the annual recurrence rate of HER2-negative DCIS was very low (less than 0.1% per annum). CONCLUSIONS: This study suggests that of HER2-overexpression might contribute to IBTR in DCIS after breast conservation.
