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W<sub>35</sub>Fe<sub>43</sub>C<sub>22</sub>비정질 합금분말의 결정화 거동
권영준 ( Young Jun Kwon ),유정선 ( Jung Sun Yoo ),박수근 ( Soo Keun Park ),이근효 ( Keun Hyo Lee ),조기섭 ( Ki Sub Cho ) 한국열처리공학회 2018 熱處理工學會誌 Vol.31 No.4
W, Fe, and carbon powders were mechanical alloyed to produce W<sub>35</sub>Fe<sub>43</sub>C<sub>22</sub> ternary alloy powders containing nanocrystal W embedded within amorphous matrix. When the powder samples were heated to the primary crystallization temperature of 735℃, most parts of their amorphous region were fully crystallized to [W,Fe]- rich M<sub>6</sub>C carbides. Interestingly, a little portion of the carbides changes to stoichiometric line compounds (M<sub>12</sub>C and W<sub>6</sub>Fe<sub>7</sub>) and a solution phase (Fe-rich bcc), and remaining parts of the crystallites were amorphized again. The resulting microstructure was retained even by cyclic heating between room temperature of 1,200oC, and thus we found that the amorphous structure can be irreversibly formed at above glass transition temperature. (Received June 11, 2018; Revised June 25, 2018; Accepted July 3, 2018)
Yoo, Yeong Myong,Park, Byeong Sub,Lee, Shin Young,Park, Kyu Jung,Jung, Hyun Joo,Pai, Ki Soo Korean Society of Pediatric Nephrology 2019 Childhood kidney diseases Vol.23 No.1
Purpose: We aimed to determine characteristics of host, causative organisms, and antibiotic susceptibility of bacteria in pediatric patients with UTI living in metropolitan area of Korea. Methods: Retrospective investigation was done for the causative organisms of UTI in 683 pediatric cases treated at Ajou University Hospital from 2012 to 2017. Patients were classified into Escherichia coli and non-E. coli group, where E. coli group was subdivided into ESBL(+) and ESBL(-) groups based on whether the bacteria could produce extended spectrum beta-lactamase (ESBL). Antibiotic susceptibility of the causative organism was also determined. Results: A total of 683 UTIs occurred in 550 patients, of which 463 (67.8%) were first-time infection and 87 (32.2%) were recurrent ones (2-7 recurrences, 2.52 average), and 64.9% were male and 35.1% were female. The most common causative organism was E. coli (77.2%) and ESBL(+) E. coli was found in 126 cases. The susceptibility of E. coli to 3rd or 4th generation cephalosporin was relatively higher than that to ampicillin or amoxicillin/clavulanic acid. ESBL(+) E. coli showed higher resistance rate to 3rd or 4th generation cephalosporin than ESBL(-) E. coli. Conclusion: New treatment guideline should be considered due to the incidence of ESBL(+) E. coli increased up to one quarter of UTI cases.