ABSTRACT
This study investigated the effects of incorporating carbon nanotubes (CNTs) into rice husk ash (RHA) sustainable concrete on its mechanical properties, permeability and microstructure characterisation. Mechanical test results suggested that the addition of 0.10 % multiwalled CNTs (MWCNTs) yielded optimal results, with increases in the compressive strength, splitting tensile strength, flexural strength, and elastic modulus of the RHA concrete at 28 days of 7 %, 23.81 %, 17.5 %, and 1.0 %, respectively. However, with further addition of MWCNTs, the mechanical properties ultimately deteriorated. Further, the incorporation of CNTs enhanced the long-term performance of RHA sustainable concrete. The addition of 0.1 % MWCNTs and 15 % RHA yielded a 20 %, 14 %, and 66 % decrease in water absorption, porosity, and chloride diffusion coefficient compared to the mixture solely containing 15 % RHA. Scanning electron microscopy of this mixture revealed the filling and bridging effects of MWCNTs between the hydration products have enhanced the performance of RHA sustainable concrete.
ABSTRACT
BACKGROUND: The tall cell subtype of papillary thyroid cancer (TCPTC) is the most common aggressive subtype and often treated aggressively. This approach may not be necessary in smaller tumours without adverse histological characteristics. METHODS: 97 patients with TCPTC defined as a height-to-width ratio of ≥3:1 and at least 30% tall cells were compared against 390 classical papillary thyroid carcinoma (CPTC) based on tumour size with recurrence free survival (RFS) as the primary outcome. RESULTS: TCPTC are more likely to present with adverse histological characteristics. In smaller tumours (<2 âcm), only central lymph node metastasis (HR7.16 p â= â0.03) and multifocality (HR10.11 p â= â0.026) increased recurrence risk. In larger tumours, TCPTC histology (HR3.78 p â= â0.002), lymphovascular invasion (HR3.02 p â= â0.014) and central lymph node metastasis (HR3.24 p â< â0.001) significantly increased recurrence risk. CONCLUSION: TCPTC tumours <2 âcm without central lymph node metastasis and multifocality are similar in risk of recurrence to classical PTC and could be managed with lobectomy.