RESUMEN
Temperature and atmosphere have a significant effect on the oxidation of MCrAlY (M = Ni, Co) bond coating. The initial growth behavior of the NiCrAlHf bond coat alloy was investigated at 1100 °C under different atmospheric conditions and using heating methods. A thick Al2O3 oxide layer and large HfO2 particles were observed, perhaps due to metastable oxide growth at low temperatures when using stepped heating. However, in air and water vapor atmospheres, the oxide scale was thinner and the HfO2 precipitates were smaller in stepped heating than in constant heating. The size and distribution of the HfO2 particles might have induced different microstructures, particularly voids within the oxide scale.
RESUMEN
OBJECTIVE: To determine the clinical and immunological characteristics and short-term outcome of children with systemic lupus erythematosus (SLE). STUDY DESIGN: A descriptive cohort study. PLACE AND DURATION OF STUDY: Paediatric Rheumatology Clinic, The Aga Khan University Hospital, Karachi, from January 2011 to December 2015. METHODOLOGY: Clinical and immunological profile and short-term outcome of children less than 16 years of age admitted in the paediatric ward, with the diagnosis of SLE was studied. Demographic data, clinical presentation, laboratory findings, immunological profile and treatment regimens of these children were evaluated. RESULTS: Thirty-two children, satisfying the criteria of American College of Rheumatology (ACR) for SLE, were enrolled during the study period of five consecutive years. A female predominance was observed with 28 (87.5%) patients being female (F:M 7:1). Mean age at symptom onset was 10.5 +2.7 years; and 8.8 +2.1 years in females and males, respectively. The mean age at diagnosis was 11.3 +2.8 years in females and 9.4 +1.9 years in males. Prolonged fever was the most common non-specific symptom found in 27 (84%), followed by pallor in 13 (41%) patients. Twenty-two (69%) children were found to be anemic and 18 patients (56%) having signs of arthritis at presentation. Renal involvement was observed in 15 (47%) patients. The most common laboratory finding was anemia, found in 22 (69%) of cases. The most common immunological markers were serum anti-neutrophil antibodies (ANA), positive in 28 (88%) patients, followed by anti double-stranded DNA antibodies, raised in 26 (81%) of cases. Out of 32, 12 patients were lost to follow-up. Of the remaining 20 children who were followed for four years, ten (50%) went into remission. CONCLUSION: Childhood-onset SLE encompasses a wide variety of manifestations with a female preponderance. Fever, arthralgia and pallor are the most frequent clinical manifestations among the children. Hemolytic anemia (HA) is the most common laboratory abnormality, with ANA and anti ds-DNA antibodies positivity in the majority of padiatric patients.