Reoxidation of liquid steel containing Al and Ti by 14%CaO-35%Al 2 O 3 -10%MgO-41%SiO 2 (in mass%) slag was investigated at 1 823 K with initial Al content of 820 mass ppm and Ti content varied from 100 to 500 mass ppm. It was observed that Al and Ti in the steel were simultaneously oxidized by SiO 2 in the slag, and the soluble oxygen was supersaturated during the course, particularly with respect to Al. Based on the experimental results, a new mechanism of the reoxidation reaction was proposed, which involves chemical reactions both at the metal/slag interface and in the bulk metal. Self-dissociation of SiO 2 into Si and O at the slag/metal interface was found to play an important role in both supersaturation of oxygen, and subsequent formation of complex oxide inclusions. Formation of inclusions having a two-layer structure where an Al 2 O 3 core was enclosed by complex Al-Ti-O oxide was explained in relation with supersaturation of oxygen in the steel.

BackgroundThe optimal surgical option for patients requiring bilateral hip replacement remains controversial. The purpose of this study was to compare surgical accuracy; functional outcome and health-related quality of life; and prosthetic-related complications and revision surgery of a simultaneous bilateral total hip arthroplasty (THA) with those of a staged bilateral THA with an interval between procedures <12 months.MethodsA total of 123 unselected consecutive patients (mean age, 43.3 years) who underwent bilateral THAs for osteonecrosis of the femoral head (ONFH) with a minimum follow-up of two years (mean, 60.2 months) were studied retrospectively; 63 simultaneous procedures served as a test group and 60 staged procedures served as a control group.ResultsThe mean postoperative leg-length discrepancy (LLD) and the percentage of patients who had an LLD >3 mm were significantly lower in the simultaneous group (P < 0.001 and P = 0.001, respectively). A higher number of cups within the safe zones, a higher correction rate, and a lower failure rate for the cup placement in the second-operated hip were also identified in the simultaneous group. The mean Harris hip score, EuroQol-5D index, and EuroQol-visual analogue scale score were all better in the simultaneous group at the latest follow-up (P < 0.001, in all comparisons). We found that the simultaneous procedure was associated with a lower incidence of postoperative prosthetic-related complications and revision surgery.ConclusionsWe suggest that bilateral ONFH could be treated with a simultaneous THA rather than a staged THA to achieve a better surgical outcome.

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