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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.
박기룡,김형덕 한국식물분류학회 2005 식물 분류학회지 Vol.35 No.4
Starch gel electrophoretic studies using 24 populations of five Korean Orostachys species were conducted to investigate allozyme variation and to test hypotheses of systematic relationships among species. The resulting phenogram showed that the populations of five Korean Orostachys species were divided into two major groups. And they were concordant with molecular and morphological data in suggesting that Orostachys was divided into two groups corresponding to the subsect. Appendiculatae and subsect. Orostachys. The low genetic identitied among Korean Orostachys species indicated that the species of Orostachys have diverged gradually through the model of geographical species. Comparing the previous genetic data from the species with similar life history and mode of reproduction, most of Korean Orostachys species revealed a significant low genetic variation, while the widespread O. japonicus showed a relatively high genetic variation among the Korean species. This kind of genetic varitation pattern might be the results of the isolated habitats, limited umbers of individuals within the populations, destruction of habitats, inbreeding and asexual reproduction in Korean Orostachys populations. The Jungdongjin population (POP 21) of O. malocophyllus was genetically unrelated with remaining populations of the same species, and this interpretation was consistent to the results from the previous palynological and morphological studies. Our allozyme data supported the taxonomic treatment of recently proposed taxa, O. iwarenge (Makino) Hara for. magnus and O. margaritifolius. 한국산 돌나물과 바위솔속 식물의 동위효소 변이와 분류군의 실체를 알아보기 위해 5종 24개 집단을 대상으로 전분전기영동을 실시하였다. 동위효소 분석 결과로 나타난 전형질도에 의하면 5종의 한국산 바위솔속 식물은 2개의 주요 군으로 나누어졌다. 그리고 이들 두 군은 기존에 분자 형질과 형태 형질을 기초로 한 결과에서 바위솔속을 Appendiculatae아절과 Orostachys아절로 나누는 처리와 일치하였다. 한국사나 바위솔속 종간의 낮은 유전적 동질성은 본 속의 종들이 지리적 종분화 과정을 통해 점진적으로 분화되었음을 시사한다. 유사한 생활사와 생식 양상을 갖고 있는 종들의 유전적 자료와 비교해 보면, 넓게 분포하는 바위솔이 좁게 분포하는 다른 종들에 비해 상대적으로 높은 유전자 변이를 나타내고 있으나, 바위솔속 식물들은 매우 낮은 유전적 변이를 보여주고 있으며, 이는 격리된 서식처, 집단 내 적은 수의 개체, 서식처의 파괴, 근친교배, 무성생식 등의 결과일 가능성이 크다. 정동진에서 채집된 둥근바위솔 집단(POP 21)은 다른 둥근바위솔과는 유전적으로는 이질적인 군으로 기존의 화분학적, 형태학적 연구 결과와도 일치하고 있다. 본 동위효소 자료는 최근 신분류군으로 발표된 울릉연화바위솔과 진주바위솔의 분류학적 처리를 지지하고 있다.
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.