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One-Pot Synthesis of Monodisperse 5 nm Pd–Ni Nanoalloys for Electrocatalytic Ethanol Oxidation
Lee, Kyungwon,Kang, Shin Wook,Lee, Su-Un,Park, Kyu-Hwan,Lee, Young Wook,Han, Sang Woo American Chemical Society 2012 ACS APPLIED MATERIALS & INTERFACES Vol.4 No.8
<P>Highly monodisperse 5 nm Pd–Ni alloy nanoparticles (NPs) were prepared by the reduction of Pd(acac)<SUB>2</SUB>/Ni(acac)<SUB>2</SUB> mixtures with tert-butylamine-borane complex (TBAB) in the presence of oleic acid (OA) and oleylamine (OAm). Employing TBAB as an effective reductant and OA/OAm combination as an effective stabilizing agent is crucial to the formation of monodisperse Pd–Ni NPs. Experimental results collectively verify that the Pd–Ni alloy NPs form through the sequential nucleation-interdiffusion process and the simultaneous reduction of both metal precursors by the one-pot protocol is the key to the formation of homogeneous NPs. The Pd–Ni NPs were well-dispersed on carbon supports and chemically dealloyed after acetic acid washing through the selective dissolution of the less noble Ni component. The Pd–Ni NP catalysts exhibited much higher electrocatalytic activity and stability for ethanol oxidation than those of a commercial Pd/C catalyst.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2012/aamick.2012.4.issue-8/am300923s/production/images/medium/am-2012-00923s_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am300923s'>ACS Electronic Supporting Info</A></P>
Kim, Soo Hyun,Shin, Jong Hee,Kim, Eui-Chong,Lee, Kyungwon,Kim, Mi-Na,Lee, Won Gil,Uh, Young,Lee, Hye Soo,Lee, Mi-Kyung,Jeong, Seok Hoon,Jung, Sook In,Park, Kyung Hwa,Lee, Jin-Sol,Shin, Myung Geun,Suh, Oxford University Press 2009 Medical mycology Vol.47 No.3
<P>There have been very few multicenter studies of the relationship between the use of antifungals and resistance to them. We investigated the antifungal susceptibility of 1,301 clinical isolates of Candida collected from nine Korean hospitals during a 3-month period in 2006 to explore the existence of this type of relationship. Antifungal usage in the preceding year, defined as the daily dose per 1,000 patient days (DDD/1,000 PD), was calculated for each hospital. Resistance to fluconazole, itraconazole, and amphotericin B was detected in 2, 9, and 0.2% of the isolates, respectively. The MIC(50)/MIC(90) values were 0.03/0.125 mg/L for voriconazole, 0.06/0.25 mg/l for caspofungin, and 0.03/0.125 mg/l for micafungin. The total usage of systemic antifungals varied considerably among the nine hospitals, ranging from 6.1 to 96.2 DDD/1,000 PD. No relationship was found between the use of fluconazole (MIC> or =64 mg/l) or itraconazole (MIC> or =1 mg/l) and resistance in the Candida species (P>0.05). However, significant correlations were found between the percentage of Candida isolates that were non-susceptible to fluconazole (MIC> or =16 mg/l) and fluconazole usage (r=0.733, P=0.025) or total antifungal usage (r=0.767, P=0.016).</P>
Lee, Yangsoon,Park, Yongjung,Kim, Myung Sook,Yong, Dongeun,Jeong, Seok Hoon,Lee, Kyungwon,Chong, Yunsop American Society for Microbiology 2010 Antimicrobial Agents and Chemotherapy Vol.54 No.9
<B>ABSTRACT</B><P>We determined the antimicrobial susceptibilities of 255 clinical isolates of anaerobic bacteria collected in 2007 and 2008 at a tertiary-care hospital in South Korea. Piperacillin-tazobactam, cefoxitin, imipenem, and meropenem were highly active β-lactam agents against most of the isolates tested. The rates of resistance of <I>Bacteroides fragilis</I> group organisms and anaerobic Gram-positive cocci to moxifloxacin were 11 to 18% and 0 to 27%, respectively.</P>
Lee, Mi-Kyung,Yong, Dongeun,Kim, Myungsook,Kim, Mi-Na,Lee, Kyungwon Korean Society for Laboratory Medicine (KAMJE) 2010 Annals of Laboratory Medicine Vol.30 No.4
<P>BACKGROUND: We utilized results from the ARTEMIS DISK Global Antifungal Surveillance Program to evaluate the species distribution and fluconazole and voriconazole susceptibilities of yeast isolates from clinical specimens in South Korea from 2001 to 2007. METHODS: Data were collected on 5,665 yeast isolates from all body sites at three locations. All investigators tested clinical yeast isolates using the CLSI M44-A disk diffusion method. Test plates were automatically read and results were recorded using the BIOMIC image analysis plate reader system (Giles Scientific, USA). Species, drug, zone diameter, susceptibility category, and quality control results were collected quarterly via e-mail for analysis. RESULTS: Candida albicans was the most common isolate, but a progressive increase in non-C. albicans Candida and noncandidal yeast species has been observed in recent years. The overall percentages of isolates in each category (susceptible, susceptible dose dependent, and resistant) were 98.8%, 0.5%, and 0.7% and 99.2%, 0.2%, and 0.6% for fluconazole and voriconazole, respectively. Candida of 3 species exhibited decreased susceptibility to fluconazole (<90% S) in the order of that seen with the resistant (R) species: C. krusei, C. guilliermondii, and C. glabrata. Emerging resistance to fluconazole or voriconazole was documented among isolates of Cryptococcus neoformans, Trichosporon spp., and Rhodotorula spp. CONCLUSIONS: The species distribution and antifungal susceptibilities of yeasts may differ according to specimen type, testing method, hospital, and geographic region. Therefore, further large-scaled, long-term surveillance studies are needed to isolate yeasts and to confirm the species distribution and antifungal susceptibilities of yeast isolates from clinical specimens in Korea.</P>
Lee, Yangsoon,Yum, Jong Hwa,Kim, Chang-Ki,Yong, Dongeun,Jeon, Eun Hee,Jeong, Seok Hoon,Ahn, Jee Young,Lee, Kyungwon Institute for Clinical Science] 2010 Annals of clinical and laboratory science Vol.40 No.1
<P>This study was performed to determine the mechanisms for acquiring carbapenem resistance in six clinical isolates of Acinetobacter baumannii. All isolates showed similar SmaI-macrorestriction patterns with less than 3 band differences by PFGE. The isolates showed a high level resistance (>32 mg/L) to both imipenem and meropenem by Etest. Phe-Arg-beta-naphthylamide lowered the MICs of carbapenems. Real-time PCR experiments showed that expression levels of the adeB gene in the six A. baumannii isolates were 10- to 40-times higher than those of imipenem-susceptible strains. Direct sequencing of PCR products showed that all isolates carried the bla(OXA-23) gene, which was preceded by ISAba1. The bla(OXA-23) probe hybridized with approximately 500-kb I-CeuI chromosomal fragments, but not with a plasmid. These findings suggest that overexpression of the AdeABC efflux pump as well as chromosome-borne OXA-23 may play a role in acquiring carbapenem resistance in our A. baumannii isolates.</P>
Lee, Hyukmin,Unemo, Magnus,Kim, Hyo Jin,Seo, Younghee,Lee, Kyungwon,Chong, Yunsop Oxford University Press 2015 The Journal of antimicrobial chemotherapy Vol.70 No.9
<P>Objectives: Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major concern globally; however, no comprehensive AMR data for gonococcal isolates cultured after 2006 in Korea have been published internationally. We determined the susceptibility of N. gonorrhoeae isolates cultured in 2011-13, the mechanism of extended-spectrum cephalosporin (ESC) resistance and the molecular epidemiology of gonococcal strains in Korea. Methods: In 2011-13, 210 gonococcal isolates were collected in Korea and their AMR profiles were examined by the agar dilution method. The penA, mtrR, penB, ponA and pilQ genes were sequenced in 25 isolates that were resistant to ESCs and 70 randomly selected isolates stratified by year. For molecular epidemiology, N. gonorrhoeae multiantigen sequence typing and MLST were performed. Results: None of the N. gonorrhoeae isolates was susceptible to penicillin G and most were resistant to tetracycline (50%) and ciprofloxacin (97%). The rates of resistance to ceftriaxone, azithromycin, cefpodoxime and cefixime were 3%, 5%, 8% and 9%, respectively. However, all isolates were susceptible to spectinomycin. Twenty-one (84%) of the 25 ESC-resistant isolates contained the non-mosaic PBP2 XIII allele; however, the remaining 4 (16%) possessed the mosaic PBP2 X allele, which has been previously associated with ESC resistance including treatment failures. Conclusions: In Korea, susceptibility to spectinomycin remains high. However, the recent emergence of ESC-resistant N. gonorrhoeae strains, including strains possessing the PBP2 mosaic X and non-mosaic XIII alleles, is a major concern and enhanced AMR surveillance is necessary to prevent transmission of these strains.</P>