Enrichment of W2B5 from WO3 and B2O3 by Double SHS Method

A second self-propagating high-temperature synthesis (SHS) was carried out to enrich the W2B5 content in the SHS product containing a mixture of various tungsten boride compounds. In the experiment, the process called Double-SHS (D-SHS) was conducted in two steps. In the first SHS reaction, an initial molar composition ratio of WO3:B2O3:Mg mixture was selected as 1:3:8. The product was then hot-leached with hydrochloric acid to eliminate MgO and Mg3B2O6 phases. The leached product, consisting of 72.6 wt.% W2B5, 16.1 wt.% WB, 8.4 wt.% W2B, and 2.9 wt.% W, was again reacted with the Mg and B2O3 mixture by second SHS. After another acid leaching step, W2B5 content in the D-SHS product was found to be 98.2 wt.%. The study showed that D-SHS is an effective method for boron enrichment in the tungsten compounds.DOI: http://dx.doi.org/10.5755/j01.ms.24.1.17834</p

Systematic review of the use of bone cement in ossicular chain reconstruction and revision stapes surgery

OBJECTIVES/HYPOTHESIS: To evaluate the effectiveness of bone cement on mean postoperative air-bone gap (ABG) and the proportion of ABG closure to within 20 dB in patients undergoing ossicular chain reconstruction or revision stapes surgery. DATA SOURCES: PubMed, Embase, and Central. METHODS: A systematic search was conducted. Studies reporting original study data were included. Relevance and risk of bias (RoB) of the selected articles were assessed. Studies with low relevance, high RoB, or both were excluded. Mean differences, risk differences, and their 95% confidence intervals were extracted for the outcomes of interest. RESULTS: Twelve studies with high relevance and moderate RoB were included for data extraction. Seven of these were two-armed studies, and five were one-armed studies. ABG closure to within 20 dB was assessed in 11 studies and achieved in 60% to 94% of patients who were treated with bone cement. Mean ABG closure ranged from 15 dB to 23 dB in patients treated with bone cement across 11 studies. Most of the two-armed studies did not show a statistically significant difference between the use of bone cement and various conventional rebridging techniques, including allograft or autograft interposition and partial ossicular replacement prosthesis. CONCLUSION: There is no sufficient evidence to support superiority of use of bone cement compared to conventional techniques. It seems from the available evidence that bone cement does not underachieve in ossiculoplasty compared to conventional rebridging techniques