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Direct fabrication of a large grain YBCO bulk superconductor without intermediate grinding step
Yi-Seul Hong,Chan-Joong Kim,Hee-Gyoun Lee 한국초전도.저온공학회 2019 한국초전도저온공학회논문지 Vol.21 No.3
Large grain YBCO bulk superconductors are fabricated by the top-seeded melt growth (TSMG) or top-seeded infiltration growth (TSIG) method. Both growth methods use at least one of YBa2Cu3O7−δ, Y2BaCuO5, BaCuO3 pre-reacted precursor powders. However, the synthesis of the pre-reacted powders includes multiple calcination runs which are cost-bearing and time-consuming. In this work, we report the successful growth of single-domain YBCO bulk superconductors directly by using the powder compact that has been pressed from the mixture of Y2O3, BaCO3 and CuO powders without any intermediate grinding step. Single-domain YBCO bulk superconductor has been also prepared by using Y2O3, BaO2 and CuO powders without intermediate grinding step. Investigations on the trapped magnetic field and microstructure of the melt-processed specimen show that the elimination of the repeated processes of calcinations and pulverization has hardly affected on the crystal growth and the magnetic properties of the grown YBCO bulk superconductors. However, it is thought that the presence of residual carbon affects on the size of Y211 particles in melt-processed YBCO bulk superconductor.
Yi-Seul Kim,김민철,권순우,Soo-Jin Kim,In-Cheol Park,가종억,원항연 한국미생물학회 2011 The journal of microbiology Vol.49 No.3
Despite the importance of meju as a raw material used to make Korean soy sauce (ganjang) and soybean paste (doenjang), little is known about the bacterial diversity of Korean meju. In this study, the bacterial communities in meju were examined using both culture-dependent and independent methods in order to evaluate the diversity of the bacterial population. Analyses of the 16S rRNA gene sequences of the bacterial strains isolated from meju samples showed that the dominant species were related to members of the genera Bacillus, Enterococcus, and Pediococcus. The community DNAs extracted from nine different meju samples were analyzed by barcoded pyrosequencing method targeting of the V1 to V3 hypervariable regions of the 16S rRNA gene. In total, 132,374 sequences, with an average read length of 468 bp, were assigned to several phyla, with Firmicutes (93.6%) representing the predominant phylum, followed by Proteobacteria (4.5%) and Bacteroidetes (0.8%). Other phyla accounted for less than 1% of the total bacterial sequences. Most of the Firmicutes were Bacillus and lactic acid bacteria, mainly represented by members of the genera Enterococcus, Lactococcus, and Leuconostoc, whose ratio varied among different samples. In conclusion,this study indicated that the bacterial communities in meju were very diverse and a complex microbial consortium containing various microorganisms got involved in meju fermentation than we expected before.
Rhodanobacter umsongensis sp. nov., Isolated from a Korean Ginseng Field
Yi-Seul Kim,김수진,Rangasamy Anandham,원항연,권순우 한국미생물학회 2013 The journal of microbiology Vol.51 No.2
A bacterial isolate designated GR24-2T was isolated from Korean soil used for cultivating ginseng (Panax ginseng C. A. Meyer). The strain was aerobic, Gram-negative, motile,and rod-shaped. It grew optimally at 28–30°C, pH 7.0, and in a range of 0–1% NaCl. Phylogenetically, the strain clustered with members of the genus Rhodanobacter. The strain exhibited the highest sequence similarities (>98%) with R. panaciterrae LnR5-47T (98.4%), R. soli DCY45T (98.2%), and R. ginsengisoli GR17-7T (98.0%). However, it also showed high sequence similarities (>97%) with some other Rhodanobacter and Dyella species. The strain contained Q-8 as the predominant respiratory quinone. The major fatty acids (greater than 10% of the total fatty acids) were iso-C17:1 ω9c (24.5%), iso-C16:0 (22.8%), anteiso-C15:0 (10.5%), and iso-C15:0(10.1%). Its major polar lipids were phosphatidylethanolamine,phosphatidylglycerol, diphosphatidylglycerol, and an unknown aminophospholipid. The DNA G+C content of strain GR24-2T was 65.6 mol%. The strain showed less than 70% DNA relatedness values between the closely related Rhodanobacter and Dyella species. The phylogeny, phenotype,DNA–DNA hybridization, and chemotaxonomic data generated in this study reveal that the isolate is a novel species of the genus Rhodanobacter. The name proposed for this strain is Rhodanobacter umsongensis sp. nov. (type strain GR24-2T =KACC 12917T =DSM 21300T).