RESUMO
Zirconium carbide (ZrC) ceramics have a high melting point, low neutron absorption cross section, and excellent resistance to the impact of fission products and are considered to be one of the best candidate materials for fourth-generation nuclear energy systems. ZrC ceramics with a high relative density of 99.1% were successfully prepared via pressureless sintering using a small amount of MoSi2 as an additive. The influence of the MoSi2 content on the densification behavior, microstructure, mechanical properties, and thermal properties of ZrC ceramics was systematically investigated. The results show that the densification of ZrC was significantly enhanced by the introduction of MoSi2 due to the formation of a liquid phase during sintering. In addition, the ZrC grains were refined due to the pinning effect of the generated silicon carbide. The flexural strength and Vickers hardness of ZrC ceramics with 2.5 vol% MoSi2 sintered at 1850 °C were 408 ± 12 MPa and 17.1 GPa, respectively, which were approximately 30% and 10% higher compared to the samples without the addition of MoSi2. The improved mechanical properties were mainly attributed to the high relative density (99.1%) and refined microstructure.
RESUMO
PURPOSE: To retrospectively evaluate safety and efficacy of conventional transarterial chemoembolization with ethiodized oil (Lipiodol) combined with CT-guided radiofrequency (RF) ablation for hepatocellular carcinoma (HCC) adjacent to the hepatic hilum. MATERIALS AND METHODS: Between January 2007 and December 2010, conventional transarterial chemoembolization combined with CT-guided RF ablation was performed in 40 patients with HCC adjacent to the hepatic hilum within Milan criteria (group A). Major complications, complete tumor ablation rate, local tumor progression rate, and overall survival were compared with 107 patients with HCC nonadjacent to the hepatic hilum (group B) treated by conventional transarterial chemoembolization combined with CT-guided RF ablation during the same period. RESULTS: Major complications included one case of large hepatic artery-portal vein fistula in group A (2.5%; 1/40) and one case of acute portal vein thrombosis, left heart failure, and tumor seeding in group B (2.8%; 3/107); the difference was not significant between the two groups (P = 1.000). There were no significant differences between the two groups in complete tumor ablation rate (80.0% vs 86.0%; P = .374), local tumor progression rates (1-year, 12.5% vs 14.1%; 2-year, 28.2% vs 24.2%; 3-year, 32.0% vs 27.6%; P = .723), and overall survival (1-year, 92.3% vs 91.8%; 3-year, 79.1% vs 79.3%; 5-year, 59.5% vs 58.4%; P = .555). CONCLUSIONS: Conventional transarterial chemoembolization combined with CT-guided RF ablation was safe and effective in selected patients with HCC adjacent to the hepatic hilum within Milan criteria.
