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박기룡,김준석,정영진,Park, Gi-Ryoung,Kim, Jun-Suk,Jeong, Young-Jin 한국섬유공학회 2008 한국섬유공학회지 Vol.45 No.6
Functional groups on multi-walled carbon nanotubes (MWNTs) were introduced by UV/ozone treatment, reacting with $HNO_3$ alone or with $H_2SO_4/HNO_3$ mixture followed by drying under different conditions. The resulting MWNTs were characterized using a UV-visible spectrometer, SEM, FT-IR, elemental analyzer, and TGA. The amount of oxygen was measured with elemental analyzer and used to check the degree of functionalization on the MWNT surface. Among the various methods tested, the one using $H_2SO_4/HNO_3$ introduced highest amount of carboxyl groups on the carbon nanotubes, while it damaged the MWNTs. Also, even with the similar amount of functional groups, dispersibility of the functionalized MWNTs in water was differed according to the functionalization method. The carbon nanotubes functionalized by reacting with $H_2SO_4/HNO_3$ started to degrade at lower temperature than the ones treated by other methods, which was due to the defects introduced during functionalization.
The allopolyploid origin of Euphorbia stevenii and E. boöphthona (Euphorbiaceae)
박기룡 한국식물분류학회 2022 식물 분류학회지 Vol.52 No.4
To elucidate the ancestry of the allopolyploids E. stevenii and E. boöphthona, I examined eleven isozyme loci and 24 morphological characters from 28 populations representing five related Euphorbia species from Australia. According to an analysis of genetic and morphological data, three diploid species differentiated recently, but two independent polyploid species are estimated to have differentiated a relatively long time ago. Fixed heterozygosity for most isozymes in E. stevenii and E. boöphthona strongly suggests that these two species are allopolyploids rather than autopolyploids. The isozyme profiles of E. stevenii indicate that it is an allopolyploid that evolved from interspecific hybridization between the diploid E. tannensis and unidentified or extinct tetraploid species. In addition, isozyme patterns strongly suggest that E. stevenii was one of the ancestors of E. boöphthona. However, E. boöphthona showed a large number of fixed alleles that were not detected in any other Australian Eremophyton species. The most likely hypothesis for the origin of E. boöphthona is that it was formed by hybridization and chromosomal doubling between an extinct diploid species and the hexaploid E. stevenii.