• Ocean and Polar Research
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• 제41권2호
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• pp.89-97
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• 2019

Long chain plant waxes (n-alkanes, n-alkanoic acids, and n-alcohols) and their carbon isotopic compositions (${\delta}^{13}C$) in geologic archives are valuable tools for paleovegetation reconstruction. However, the sensitivity of different plant wax constituents to vegetation shift is not well understood. This study explores controls on the variation in ${\delta}^{13}C$ values of long-chain n-alkanes ($C_{27}$ to $C_{33}$) and n-alkanoic acids ($C_{26}-C_{30}$) in the Gulf of Mexico core sediments (ODP 625B) near the Mississippi River delta. n-Alkanoic acids' ${\delta}^{13}C$ values were higher than those of n-alkanes by 1-2‰ on average and such a pattern is the opposite from their isotope fractionation observed in living plants: 1-2‰ smaller in n-alkanes than n-alkanoic acids. We attribute this offset to contributions from aquatic plants or microbes that produce high concentrations of $^{13}C-enriched$ long-chain n-alkanoic acids. The sensitivity of n-alkanes and n-alkanoic acids to vegetation and climate varied among chain lengths. The $n-C_{33}$ alkanes were most sensitive to $C_4$ grassland expansion among n-alkane homologues, while no specific trend was observed in n-alkanoic acids. This is due to the similarity in n-alkanoic acid concentrations between $C_3$ and $C_4$ plants by homologues and low terrestrial plant-derived n-alkanoic acid contributions to the sediments. The results of this study suggest that long chain n-alkanoic acids' ${\delta}^{13}C$ values in sediments may be influenced by contributions from different sources such as aquatic plants or microbial inputs and therefore interpretations regarding this matter should be cautiously formulated. We suggest that there is a need for further studies on characterizing long-chain n-alkanoic acids ($C_{26}-C_{34}$) in aquatic plants and microbes from various climates and environments in order to investigate their production and integration into sedimentary archives.

• 공업화학
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• 제4권2호
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• pp.381-392
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• 1993

탄소수 10~18 범위에 있는 고급지방산 즉, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid 및 octadecanoic acid 등을 $SO_3$-dioxane complex로 ${\alpha}$-술폰화 한 다음, dodecanol-1에 에틸렌옥사이드를 5몰, 10몰, 20몰씩 부가시켜 제조한 POE 알킬 에테르류와 각각 반응시켜 15종의 올리고머 음이온성 계면활성제를 좋은 수율로 합성하였고, 이들 최종 합성화합물에 대하여 IR, NMR, 원서분석 등 기기분석을 행하여 분리확인하였다.

• 한국대기환경학회지
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• 제33권3호
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• pp.265-276
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• 2017

The $PM_{2.5}$ samples were obtained from coal combustion with the four different combustion temperatures (550, 700, 900 and $1100^{\circ}C$) to understand chemical composition in carbonaceous aerosol. OC concentration was the highest when the combustion temperature was $550^{\circ}C$, while, the highest concentration for EC was shown at $700^{\circ}C$ of the coal combustion temperature. However, OC concentrations were very low and EC was not detected when the temperature was over $900^{\circ}C$. It indicates complete combustion was achieved when the combustion temperature was over $900^{\circ}C$. For six groups of organic compounds, n-alkanes and n-alkanoic acids were predominant at all of the combustion temperature in smoke of coal combustion, while, PAHs was only detected at $550^{\circ}C$. The diagnostic ratios of PAHs calculated in this study were 0.59 for Fluoranthene/(Fluoranthene+Pyrene), reflecting the characteristics of coal combustion. The Carbon number Preference Index (CPI) values of n-alkanes which ranged from 0.9 to 1.3 also showed the characteristics of coal combustion.

• 대기
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• 제31권3호
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• pp.267-282
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• 2021

Characteristics of carbonaceous components and organic compounds in PM_2.5 over the atmosphere of the Yellow Sea were investigated. PM_2.5 samples were collected onboard the meteorological research vessel, GISANG 1, over the Yellow Sea during the YES-AQ campaign in 2018 and 2019, respectively. The average concentrations of carbonaceous components in this region were 2.59 ± 1.59 ㎍ m^-3 for the OC, 0.24 ± 0.10 ㎍ m^-3 for the EC, 2.14 ± 1.30 ㎍ m^-3 for the WSOC and 1.17 ± 0.94 ㎍ m^-3 for the HULIS-C, respectively. The total concentration of 56 organic compounds (ΣOCs) accounts for 10% of OC. The main group among organic compounds were dicarboxylic acids which account for 57% of ΣOCs, followed by n-alkanoic acids accounting for 34% of ΣOCs. In n-alkanoic acid distribution, hexanoic (C_6:0) and octanoic (C_8:0) acids which are low molecular weight n-alkanoic acids and known as emitted from marine biogenic activities were dominant in this region. Furthermore, non-HULIS-C fraction increased when the air mass originated from the marine region rather than the continental region. When the Asian dust episode was observed, the WISOC concentrations along with the levoglucosan were increased, while the haze episodes caused the increase of WSOC, HULIC-S and DCAs. In this study, we found that the components of carbonaceous and organic aerosols in PM_2.5 over the Yellow Sea were changed with the specific air pollution episodes. It indicates that the physicochemical properties of PM_2.5 can be changed by the air pollution episodes in this region.

• 공업화학
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• 제19권5호
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• pp.504-511
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• 2008

두 종류의 니트로아조벤젠 유도체들, 즉 4-{4'-(니트로페닐아조)펜옥시}알칸 산(NAAn, n = 2~8, 10, 알킬 사슬 중의 메틸렌 기의 수) 그리고 4-{4'-(니트로페닐아조)펜옥시}알카노일 클로라이드(NACn, n = 2~8, 10)을 합성함과 동시에 이들의 열방성 액정의 거동을 검토하였다. NAA6은 쌍방성 네마틱 상을 형성하는 반면 NAA2을 제외한 나머지 유도체들은 단방성 네마틱 상을 형성하였다. NAAn 그리고 NACn이 나타내는 액체 상에서 네마틱 상으로의 전이온도($T_{iN}$) 그리고 $T_{iN}$에서의 엔트로피 변화(${\Delta}S$)는 n의 변화에 따라 현저한 홀수-짝수 효과를 나타냈다. 그러나 NAAn의 $T_{iN}$ 그리고 ${\Delta}S$는 n이 동일한 NACn의 $T_{iN}$ 그리고 ${\Delta}S$ 값에 비해 대단히 높았다. 이러한 사실은 카복실 그룹간에 작용하는 수소결합력에 의해 초래되는 것으로 생각된다. NAAn 그리고 NACn이 나타내는 액정 상의 열적 안정성과 질서도 그리고 홀수-짝수 효과는 4-(알콕시)-4'-니트로아조벤젠들에 대해 보고되어 있는 결과와는 현저히 달랐다. 이러한 특성을 분자의 이방성 그리고 온도에 의존하는 치환기 그룹의 유연성 차이 견지에서 검토하였다.

• 한국입자에어로졸학회지
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• 제9권3호
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• pp.187-197
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• 2013

To understand the characteristics of organic aerosol(OA) at the background atmosphere of Korea, an observation of atmospheric PM10 was conducted at a Global Atmospheric Watch(GAW) station operated by the Korean Meteorological Administration at Anmyon Island during 2010. Various organic compounds were analyzed from 26 samples by using a gas chromatography-mass spectrometer. Water soluble organic carbon(WSOC) was also analyzed by using a total organic carbon(TOC) analyzer. Among 6 classes with 68 target compounds detected, the classes of n-alkanoic and alkenoic acids ($326.67{\pm}75.40ngm^{-3}$) and dicarboxylic acids ($323.74{\pm}361.89ngm^{-3}$) were found to be major compound classes in the atmosphere of Anmyon Island. Compared to the previous results reported for 2005 spring samples at Gosan site, the concentrations of organic compounds at Anmyon Island were 3-10 times higher than Gosan site due to the difference of location and sampling period. The concentrations of organic compounds were varied with the atmospheric conditions. Significant increase of the concentrations of dicarboxylic and carboxylic acids in the smog episode indicated that secondary oxidation of organic compounds was major factor to increase OA concentration during smog episode in the Anmyon Island. It was found that the compositions of the OA measured at Anmyon Island were dependent on the air parcel trajectories.

• Journal of Microbiology
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• 제35권2호
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• pp.127-133
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• 1997

Biosynthesis of polyhydroxybutyrate and copolymer consisting of 3-hydroxybutyrate and 3-hydroxyvalerate [poly(3HB-co-3HV)] by Bacillus thuringiensis R-510 grown with glucose or with mixtures of glucose and propionate was investigated. n-Alkanoic acids other than propionate were not precursors of 3HV units. The fraction of 3HV unit in the copolymer increased from 0 to 84 mol% of 3HV. Polymer yield decreased as the fraction of propionate was increased but the molecular weight distribution was not affected by the composition of carbon substrate. The minimum melting temperature (around 65.deg.C) of poly (3HB-co-3HV) copolymers was observed for the polymer bearing approximately 35 mol% of 3HV. Polyhydroxyalkanoates production by this organism was not dependent on nutritional limitation, but remarkably influenced by dissolved oxygen concentration in the culture medium. Low level of dissolved oxygen concentration prevented spore formation in the cells and stimulated the synthesis of polyhydroxyalkanoate. The composition of poly (3HB-co-3HV) produced by B. thuringiensis R-510 lyhydroxyalkanoate. The composition of poly(3HB-co-3HV) propduced by B. thuringiensis R-510 varied according to the growth time. However, there was no evidence that polymers isolated from cells were mixtures of immiscible polymers.

• 대한화학회지
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• 제44권5호
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• pp.403-409
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• 2000

1,4,7,10-tetraaza13,16-dioxacyclooctadecane-N,N',N",N'"-tetraacetic acid (1), 1,4,7,10-tetraaza-13,16-dioxactclootadecane-N,N',N",N'"-tramethylacetic acid (2), 및 1,4,7,10-tetraaza-13,16-dixacyclooc-tedecane-N,N',N",N'"-tetrapropionic acid (3)와 $Zn^{2+}$ 착물의 형성 및 해리 속도를 멈춤-흐름법 및 분광학적방법으로 측정하였다. 측정 조건을 온도 25.0$\pm$0.1 $^{\circ}C$ 및 이온강도 0.10 M NaClO4 이었다. $Zn^{2+}$이온과 1과 2의 형성 반응은 빠르게 중간 생성물($ZnH_3L^+$)를 형성한다. 여기서 $Zn^{2+}$ 이온은 부분적으로 배위되어 있고 속도 결정 단계는 최종 생성물이었다. pH범위 4.76-5.76에서, 2가 양성자($H_2L^{2-}$) 형태가 매우 낮은 농도임에도 불구하고 속도론적으로 활성화종임을 알 수 있었다. 또한 중간체 착물의 안정도 상수(log$K_{(ZnH_3L^+)}$)와 고유 물분자-보조 속도상수(KOH)가 속도론적 자료로부터 계산되었다. $Zn^{2+}$이온과 1,2, 및 3의 해리 반응은 아세테이트 완충 용액 하에서 청소군 $Cu^{2+}$ 이온을 이용하여 측정하였다. 모든 착물의 해리 반응은 산-무관 및 산-촉매 반응으로 진행됨을 알 수 있었다. $Zn^{2+}$ 착물의 해리 속도에 영향을 미치는 완충 용액 및 $Cu^{2+}$농도의 효과를 알아보았으며, 아울러 리간드 효과를 곁가지에 매달려있는 치환기와 킬레이트 고리크리로 논하였다.