Al-Si alloy matrix composites reinforced with different weight fractions of Al 2 O 3 particles up to 25 wt% were fabricated by stir casting method. The effect of weight fraction of Al 2 O 3 and heat treatment on the wear behavior of Al-Si alloy and its composites was investigated. The results showed that wear resistance of the investigated composites was improved by heat treatment and Al 2 O 3 particles addition. The effect of heat treatment on the corrosion behavior of composites compared with its matrix in 3.5 % NaCl at 600 rpm using electrochemical potentiodynamic polarization test was also investigated. The corrosion resistance of the composites with 10, 15, and 20 % Al 2 O 3 particles was higher than that of the matrix alloy. Heat treatment of Al-Si alloy and its composites resulted in marked improvements in the corrosion resistance as compared with these materials in the as-cast condition.

Background and study aim: Choledocholithiasis due to common bile duct (CBD) stones is a critical condition in children. The aim of this study was to evaluate the efficacy and safety of endoscopic retrograde cholangiopancreatography (ERCP) in management of CBD stones in children. Patients and methods: Twenty five children suffering from obstructive jaundice were diagnosed and selected after completion of full laboratory and radiological investigations in the period from June 2010 till December 2013 and were admitted to the Surgery Department Zagazig University Hospitals, Egypt. Patients were classified into 2 age groups below and above 6 years to decide the diameter of ERCP scope and the stents used in the procedure. Group A; 0-6 years were 12 patients and Group B; 6-15 years were 13 patients. Results: ERCP was adequate in helping to predict biliary ductal stones and removal of them in all patients with no reported diagnostic or therapeutic failure. The stent placement was indicated in 21 of the 25 (84%) children, the other 4 children (16%) just sludge was cleared using basket forceps without the need for stent insertion. Two to three weeks later laparoscopic cholecystectomy was successfully performed to all indicated children with removal of the stent after 2 to 3 weeks. There rate of ERCP complications was 12% (3 cases), one case reported mild pancreatitis and 2 cases reported mild cholagnitis. Conclusion: The encouraging results of this study with very minimal insignificant complications of ERCP (safety) and good results of ERCP in treatment of CBD stones in children (efficacy) recommend that children with choledocholithiasis due to CBD stone or sludge should be treated by endoscopic CBD stone or sludge removal.