The mechanical strength variation of ambient cured Alkali-activated mortar (AAS) upon exposure to elevated temperatures from 200 to 1200 °C was studied in this article. Slag was activated by the combination of sodium silicate liquid (Na2SiO3) and sodium hydroxide (NaOH) with different Na2O concentrations of 4%, 6%, 8%, and 10% by slag weight. Mechanical properties comprising compressive strength, flexural strength, and tensile strength before and after exposure were measured. Thermogravimetric analysis (Thermogravimetric analysis (TGA) and Derivative thermogravimetric (DTG)), X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDS) were also used for strength alteration explanation. The results indicated that Na2O concentration influence on strength variation of AAS mortar was observed clearly at temperature range from ambient temperature to 200 °C. The melting alteration of AAS mortar after exposed to 1200 °C was highly dependent on concentrations of Na2O.

The aim of this work was to study the mechanical strength and microstructure changes of alkali-activated slag mortar (AAS mortar) after being heat treated in the temperature range of 200–1000 °C. The AAS mortar was cured in the ambient condition (20 ± 5 °C, 60 ± 5% RH) (Relative humidity: RH) and high temperature condition (80 °C) for 27 days with three different heating regimes: curing in a dry oven, curing in sealed plastic bags, and in a steam environment. The activator for the AAS synthesis was a mixture of sodium silicate solution (water glass) and sodium hydroxide (NaOH) with a SiO2/Na2O weight ratio of 1, and a dosage of 4% Na2O by slag weight. Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) incorporated with energy-dispersive X-ray spectroscopy (EDX) were used to assess the mortar microstructure change. The results revealed that the curing method significantly affected the mechanical strength of AAS at temperatures lower than 800 °C. The heat treatment at late age of 28 days was more beneficial for compressive strength enhancement in specimens without using heat curing methods.

Background: This study explored the prevalence of frontal cells and the relationship between different types of frontal cells classified using the International Frontal Sinus Anatomy Classification (IFAC) and frontal sinusitis. Methods: A retrospective cross-sectional study was conducted with 1006 CT scans of paranasal sinuses. Identification of frontal sinus cells was based on IFAC. The scans were classified into no frontal sinusitis, frontal sinusitis, isolated frontal sinusitis, no sinusitis. Results: Agger nasi cells were the most common (91.9%). The prevalence of supra agger cell (SAC) was 28.7%, while the supra agger frontal cell (SAFC) was only 15.8%, the supra bulla cell (SBC) was 59.7%, the supra bulla frontal cell (SBFC) was 25.8%. Supra orbital ethmoid cell (SOEC) and frontal septal cell (FSC) were identified in 6.9% and 14.3% of the cases, respectively. Patients with SAFCs and SBFCs were significantly more likely to develop frontal sinusitis (Odds Ratio (OR)=1.78, 95% confidence interval (CI) 1.24-2.56 and OR=2.70, 95% CI 1.98-3.66). Isolated frontal sinusitis was found in 10 scans and was associated with the presence of SAC (OR=3.76, 95% CI 1.02-13.90). Conclusion:In Vietnamese adult patients, frontal cells based on IFAC were prevalent and were associated with frontal sinusitis development, including isolated frontal sinusitis.

Background: The effectiveness of nonabsorbable and biodegradable nasal packing is still controversial, and the choice of nasal packing type can alter the outcome of endoscopic sinus surgery. This study compared the effectiveness of Posisep and Merocel as nasal packing materials with regard to hemostasis, adhesion, wound healing, patient’s satisfaction and health-related quality of life after endoscopic sinus surgery (ESS). Methods: A prospective, randomized, double-blinded, controlled trial was conducted in patients with chronic rhinosinusitis refractory undergoing symmetrical bilateral ESS. At the completion of surgery, a nasal packing (either Merocel or Posisep) was randomly chosen and placed into the middle meatus of each nasal cavity. All patients were scheduled for follow-up visits at 24 hours, 5 days, 3 weeks, and 5 weeks days after surgery. Health-related quality of life was measured using the Sino-Nasal Outcome Test (SNOT-22). The overall inflammatory burden of chronic rhinosinusitis was measured by the Lund-Mackay postoperative endoscopic score (LMES). Results: Among 62 patients included in data analysis (n = 31 for each group), the mean age was 42.4 years and 54.8% were females. Patients with Posisep after ESS had more improvement and better symptoms measured through SNOT-22 and LMES at 24 hours, 5 days, and 3 weeks than those with Merocel after ESS. While some aspects measured by LMES such as discharge and scarring were still better until 5 weeks after surgery, all symptoms measured by SNOT-22 were similar between the 2 groups 5 weeks after surgery. Conclusion: Posisep containing chitosan provided patients with a better quality of life throughout the early recovery period compared with Merocel. Although more studies are needed, our findings support the use of Posisep after ESS.