Research on crack propagation behaviour of EB-PVD TBCs based on TGO evolution.

Thermal Barrier Coatings (TBCs) are functional coatings used to protect high-temperature components that are prone to early damage and premature failure under the influence of complex working conditions. This paper examines the crack propagation behaviour of 8% yttria-stabilized zirconia (8YSZ) EB-PVD TBCs under different oxidation conditions at 1100 °C. The morphology of interfacial cracks after oxidation was summarized and the evolution of thermally grown oxide (TGO) was quantified. Based on the evolution of TGO, the causes of crack propagation were analyzed. For the specimens after oxidation experiment, the interfacial crack propagation behaviour was observed and analyzed by SEM, and the reason of lateral crack propagation was explained from the perspective of interfacial fracture toughness. The reason for crack deflection is analyzed from the perspective of energy release rate. The equivalent thickness, normalized rumpling index and two-dimensional roughness index were calculated, then the TGO growth behaviour was comprehensively analyzed and related to the crack propagation.

Asymptomatic bacteriuria in antenatal patients in ilorin, Nigeria.

OBJECTIVE: To determine the prevalence of asymptomatic bacteriuria, bacteriology and sensitivity pattern in Ilorin using the gold standard of urine culture. METHODS: A prospective study was carried out from 1st July to 31st October 2007, at the University of Ilorin Teaching Hospital (UITH) on 125 consenting asymptomatic pregnant women. A structured proforma was used to collect information from the women and a midstream urine specimen collected for bacteriological culture. RESULTS: Of the 125 pregnant women, 50 had bacteriuria on urine culture giving a prevalence of 40%. The mean age of the women was 28.5 years with a standard deviation of 4.95. The age ranged between 14 and 40 years. Staphylococcus aureus was the commonest pathogen isolated (72%), followed by Proteus spp (14%). Most of the organisms showed good sensitivity to Nitrofurantoin and gentamicin. CONCLUSION: The prevalence of asymptomatic bacteriuria in Ilorin is high and routine urine culture is advocated for all pregnant women at booking.