The use of lightweight concrete can provide specific advantages that are favoring for mitigating seismic risk in building design. On the other hand, a significant reduction of carbon footprint could be possible through the use of geopolymer concrete. However, geopolymer concrete is mostly assessed through small specimens without reinforcement elements. This paper aims to couple the advantage of lightweight mixtures and ambient-cured geopolymerization in reinforced beams. To do this, engineering performance of reinforced lightweight geopolymer concrete was extensively investigated with different aspects. In mixtures, pumice and volcanic tuff aggregates were used with an appropriate gradation. Flexural strength, deflection capacities, initial stiffness, ductility, and energy dissipation capacity of reinforced geopolymer beams were investigated with the proposed configuration. Compressive strength and unit weight of the developed mixtures were also evaluated to meet design requirements for lightweight concrete. Results indicated that certain engineering properties (energy dissipation capacity and initial stiffness) of developed lightweight geopolymer concrete were considerably comparable with lightweight Portland cement-based concrete. Although compressive strength and unit weight of the developed geopolymer mixtures were satisfying, microstructural analysis indicated a weak bonding behavior between paste and lightweight aggregates.

Background/Aims: Hepatitis B reactivation (HBVR) is an important risk of treatment with tumor necrosis factor inhibitors (anti-TNF). While antiviral prophylaxis is recommended before treatment in HBsAg-positive patients, there is no clear approach for the follow-up or prophylactic treatment of patients with past hepatitis B virus (HBV) infection. The aim of this study was to evaluate patients with past HBV infection treated with anti-TNF for HBVR and/or HBVR-associated biochemical breakthrough. Material and Methods: Patients who received anti-TNF therapy and had past HBV infection (HBsAg negative, anti-HBc IgG positive, anti-HBs negative or positive) were screened and evaluated at 3-month intervals for viral and biochemical breakthrough according to a liver function test (ALT) and HBV DNA level. Results: A total of 653 patients who received anti-TNF therapy were screened. Ninety of these patients had past HBV infection and had not received antiviral prophylaxis. Anti-HBs positivity and isolated anti-HBc IgG positivity were seen in 87.7% (n: 79) and 12.2% (n: 11) of these patients, respectively. No HBVR was seen in 20% (n: 18) of patients who were followed up regularly, and no HBVR-associated biochemical breakthrough was found in patients who were not followed up regularly in terms of HBV DNA level (80%, n: 72) during the follow-up period (26±16 months). Conclusion: The use of anti-TNF in patients with past HBV infection has a low risk for HBVR. A follow-up for the ALT and HBV DNA levels at 3-month intervals may be more reasonable than administering antiviral prophylaxis to all patients.