The joining of dissimilar A5052 and A5J32 alloy sheets with thicknesses of 1.5mm and 1.6mm, respectively, was carried out using the Friction Stir Welding (FSW) technique. The tool rotated at a speed in a range of 1000 rpm to 1500 rpm with a welding speed ranging from 100 mm/min to 400 mm/min. The hardness and tensile properties of the friction stir welded A5052/A5J32 joint were investigated according to the fixing location. In the case where the A5J32 aluminum alloy was fixed on the retreating side, defect-free welds were obtained under all welding conditions. However, in the case where the A5052 aluminum alloy was fixed on the retreating side, some welding defects were observed at the joint under certain welding conditions with a lower heat input. However, the welding defects had no effect on the mechanical properties. A good correlation between the hardness distribution and the welding zones was observed. The experimental results showed that the tensile properties differed depending on the fixing location of the materials and were also affected by the welding conditions.
Acinetobacter baumannii (AB) is a common pathogen found in patients with hospital-acquired pneumonia all over the world. Community-acquired AB pneumonia, however, is very rare and has seldom been reported in Asia-Pacific countries. Community-acquired AB pneumonia has a fulminant course and is associated with a higher mortality than hospital-acquired AB pneumonia. In Korea, no case of fatal community-acquired AB pneumonia has been reported to date. Here, we describe the first fatal case of fulminant community-acquired AB pneumonia in Korea.
The dissimilar Al alloys, 5052 and 5J32, were joined by friction stir welding (FSW) technique under several welding conditions, including material arrangement. The tool rotation speeds were 1000 and 1500 rpm, and the welding speeds were varied within the range from 100 to 400 mm/min. At a tool rotation speed of 1000 rpm, all joints with the 5052 on the advancing side exhibited better properties than those with the opposite arrangement. When the 5J32 was placed on the advancing side, defect-free welds were obtained under all welding conditions. However, when the 5J32 was placed on the retreating side with a rotation speed of 1500 rpm, some defects were detected below the top surface of the retreating side. Furthermore, fractographs of the defects indicated an evidence of liquation cracking during FSW. The experimental results showed that the weld formation and mechanical properties depended upon the material arrangement as well as the conventional welding parameters.
The morphology and crystallography of M 2 C carbide precipitates in the ferrite matrix in M50NiL alloy were investigated using transmission electron microscopy (TEM). A new orientation relationship (OR), (010) ␣ // (0111) C and [100] ␣ // [2110] C between the carbide and the matrix was determined. The observed OR leads to a small lattice misfit on the matching planes between the two phases. Results of TEM studies of the particle morphology and electron diffraction of the carbide are consistent with the proposed OR.
Streptococcus suis causes meningitis and sepsis in pigs, but human infection has increased over the past few years in those who are exposed to pigs or raw pork. Most cases have occurred in Southeast Asia, but only two cases have been reported in South Korea, presenting with arthritis and meningitis. Here, we report a rare case of S. suis infection, a 60-year-old sailor, who visited the emergency room presenting septicemia, pneumonia with empyema and meningitis, showed full recovery; however, neurologic sequale of severe cognitive dysfunction was present after the usage of antibiotics and percutaneous drainage. S. suis was isolated from blood and pleural fluid and the strain was susceptible to penicillin and vancomycin. Increased awareness of S. suis infection and prevention are warranted.
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