BaZrO3 is by far the most inert crucible material that has been used for flux growth of high quality single crystal YBCO superconductors. The performance of this otherwise resilient material is primarily determined by secondary phases, hence high chemical purity, very high phase purity, and high sintered density are required for sustained corrosion resistance (Erb et al 1995 Physica C 245 245–51, Liang et al 1998 Physica C 304 105–11). In this paper we report new data on the solid-state processing properties of BaZrO3, showing strong effects of stoichiometry and processing conditions on the physical properties of powders. If the constituents are reacted fully there is a sharp transition in the particle size and surface areas of the BaZrO3 powders obtained near to the phase boundary where the Ba/Zr mole ratio is unity. Repeated calcination and regrinding of powders was shown to increase the phase purity of processed powders. Precise control over stoichiometry is required to produce crucibles with corrosion resistance adequate for single crystal growth experiments. Optimal corrosion resistance was observed over a narrow Ba:[Zr+Hf] mole ratio range between 1.001 and 1.007 (± 0.002). The corrosion resistance of BaZrO3 is acutely sensitive to residual ZrO2, whose phase abundance must be very strictly minimized by control of stoichiometry and processing conditions, whereas tolerances for Ba-rich phases are less demanding. Measurements of YBCO single crystals grown in one of these crucibles have been made for a range of oxygen contents, i.e. hole concentrations. These show that the crucibles are suitable for growing high quality single crystals.

With anaesthesia being administered more often outside of theatre in areas such as radiology suites, the occupational risk to anaesthetists from ionizing radiation may have increased. To determine radiation exposure from X-ray sources during normal anaesthetic practice, passive personal radiation monitoring devices were used to record the occupational exposure to radiation of 29 anaesthetists over a one calendar month period. Occupational whole body effective dose was calculated and extrapolated to give an estimated annual radiation exposure. Seven of the 29 anaesthetists recorded a dose that was higher than the minimum detectable limit. Extrapolating to estimate yearly doses, no anaesthetist would have approached the annual occupational dose limits for ionizing radiation. The maximum extrapolated annual whole body effective dose was 2.14 mSv, the Australian Recommendation and National Standard for occupational exposure being less than 20 mSv per year. The anaesthetist with the highest exposure would have exceeded the yearly recommended exposure limit for pregnant women (1 mSv). Even if they had worked all sessions in a radiation exposed environment, this person would not have exceeded the yearly annual occupational dose limits for ionizing radiation for non-pregnant staff, provided they had worn a standard protective lead gown. The collar dose for this person was 7.08 mSv which may represent a significant risk to the thyroid if a protective lead collar was not worn. Although anaesthetists' radiation exposure is within acceptable limits, caution should be taken in rostering pregnant staff to anaesthetize where radiation exposure occurs, and all anaesthetists should routinely wear thyroid collars in such areas.

Background:: Early diagnosis can improve melanoma prognosis. Dermoscopy can enhance early melanoma recognition. Objectives: Examine the dermoscopy features of early melanoma up to a maximum surface diameter of 6mm. Methods: Consecutive melanoma cases were collected from two medical practices in Sydney, Australia 2019-2021. Dermoscopy features were recorded for melanomas by maximum surface diameter, to the nearest 0.1 mm, to a limit of 6mm. Results: Total cases numbered 100; with males (n=48) and females (n=52), melanoma in situ (MIS, n=96) and invasive (n=4). The most frequent anatomic sites on both males and females were back (males n=20, females n=16) then knee or leg (males n=8, females n=12). Minimum respective MIS diameters for males/females was 1.2/2.0mm and for invasive cases 2.0/3.4mm. Highest frequency dermoscopy features were: light brown, dark brown, grey and asymmetric melanoma shape. Brown pigment in hair follicles were more frequent on legs compared to other anatomic sites [OR 14.6, 95%CI (1.29-165.17), p 0.03]. Pseudopods were substantially increased in frequency comparing diameters less than 4mm with 4 up to 6mm [OR 8.81, 95%CI (1.05-73.9), p 0.004]. Structureless area cases recorded increased grey [OR 7.08, 95%CI (1.61-31.11) p=0.01]. Melanomas with edge angulation were noted in 20-50% of cases across diameters 1-6mm, less frequent were pigmented circles and polygons. Conclusion: Watch out! MIS presented with a surface diameter of just 1.2 mm and invasive melanoma 2.5mm. Pseudopods were a strong clue to melanomas with a surface diameter less than 5mm. We found melanomas on leg sites displayed more frequent pigmented hair follicles.