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This study was conducted to investigate the characteristics of the AlCrCuFeNi high-entropy alloy (HEA) synthesized through mechanical alloying (MA). In addition, effects of Process Control Agent (PCA) amount and milling time were investigated using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The results indicated that the synthesized AlCrCuFeNi alloy is a dual phase (FCC + BCC) HEA and the formation of the phases is strongly affected by the PCA amount. A high amount of PCA postponed the alloying process and prevented solid solution formation. Furthermore, with an increase in the PCA amount, lattice strain decreased, crystallite size increased, and the morphology of the mechanically alloyed particles changed from spherical to a plate-like shape. Additionally, investigation of thermal properties and annealing behavior at different temperatures revealed no phase transformation up to 400 °C; however, the amount of the phases changed. By increasing the temperature to 600 °C, a sigma phase (σ) and a B2-ordered solid solution formed; moreover, at 800 °C, the FCC phase decomposed into two different FCC phases.

Background: Umbilical vein catheterization is usually conducted for preterm neonates in neonatal intensive care units to administer medication, fluid and nutrition, and blood transfusion. However, catheter tip malposition can cause complications. Objectives: There are different methods to detect the accuracy of catheter’s position; hence, this study aimed to compare the diagnostic accuracy of radiography vs echocardiography to determine the accurate tip position of umbilical vein catheter. Methods: This cross-sectional study was performed on all 104 neonates admitted to the neonatal intensive care units of hospitals affiliated to Shiraz University of Medical Sciences from March 2017 to January 2018. At first, the length of the catheter was estimated based on Dunn method. After catheterization, thoraco-abdominal radiography and echocardiography were performed by a pediatric radiologist who was blinded to the study objectives, and the data were recorded in two forms. Finally, data were analyzed by McNemar’s test, using SPSS 17 software. Results: The sensitivity, specificity, positive predictive value and negative predictive value by radiography and echocardiography for the catheter tip position in the inferior vena cava-right atrium junction was calculated 100%. Moreover, catheters were located in the ductus venous, inferior vena cava, inferior vena cava-right atrium junction, right and left atrium in echocardiography were in the radiograph equal to thoracic vertebrae of T9-T11, T9, T6-T10, T5-T8, and T4-T6, respectively. Conclusions: Our study suggests that even though echocardiography is as reliable as radiography for early detection of the catheter tip position, it can also avoid complications of catheter malposition quicker than radiography.

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