• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.8
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• pp.1156-1164
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• 2010

Structured lipids (SLs) were synthesized by enzymatic interesterification with evening primrose oil (EPO) and rice bran oil (RBO) in a batch-type reactor. The interesterification was performed using a water shaker for 24 hr at $55^{\circ}C$. Mixing speed was set at 200 rpm and Lipozyme RM IM (immobilized lipase from Rhizomucor miehei, 10% by weight of total substrates) was used as a biocatalyst. Rice bran oil and evening primrose oil were interesterified with various molar ratios (RBO : EPO, 1:3, 1:4, and 1:5 mol/mol). Reversed-phase high performance liquid chromatography connected with evaporative light-scattering detector was performed to separate the triacylglycerol (TAG) species of SLs. In the fatty acid analysis, $\gamma$-linolenic acid (7.9 mol%), linoleic acid (67.3 mol%) and oleic acid (13.2 mol%) were the most abundant fatty acids in the SLs. During 24 hr reaction, most of the reaction occurred within 3 hr. TAG compositions, tocopherols and phytosterols were also analyzed. In the TAG species analysis, LLL (ECN=42, L=linoleic acid) dramatically decreased when the reaction time increased.

• Journal of the Korean Chemical Society
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• v.37 no.5
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• pp.491-495
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• 1993

Synthesis of polymer-supported azacrown ether ion exchanger, {(4,5): (13,14)-dibenzo-6,9,12-trioxa-3,15,21-triazazabicyclo[15.3.1]heneicosa-1(21),17,19-triene-2,16-dione : DBPDA ion exchanger}, and its ion binding ability to alkali metal $(Li^+,\;Na^+,\;K^+)$ picrates were studied. The binding constants $(K_b)$ of DBPDA ion exchanger to the alkali metal picrates in ether type solvents were obtained by spectrophotometry. Binding constants of alkali metal ions were in the order to Li < Na < K, and alkali metal ions were formed 1 : 1 complexes with ligands of DBPDA ion exchanger. Also, $K_b$ was found to depend on the variables such as solvent and temperature. The binding constants for the complexes were obtained in the ranges of $2{\times}10^3{\sim}4{\times}10^4M^{-1}$. In order to obtain the enthalpy (${\Delta}$H) and entropy changes (${\Delta}$S)n the complexation process, Kb were plotted against the temperature in the ranges of 10∼40$^{\circ}C$ according to the van't Hoff theory. Enthalphy and entropy changes were found in the ranges of -2.71∼-3.79 kcal/mol, and -16.52∼-20.57 eu, respectively.

• Journal of Conservation Science
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• v.29 no.4
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• pp.437-444
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• 2013

We studied for the chemical characterizations of the charred residues obtained from the ancient potteries in the Proto-Three Kingdom period from archaeological sites in Joong-do, Chuncheon. Organic components of the charred residues were extracted and analysed using mass spectrometry and infrared spectroscopy. Lipid profiles from these samples were not identified in gas chromatography-mass spectrometry. Bulk stable isotope analyses of charred residues was used to infer an average values of the foods prepared. The average carbon isotope values (${\delta}^{13}C$) of the residues are $-14.7{\pm}2.8$‰ (ranging from -8.7‰ to -18.4‰, n=9), and nitrogen isotope values (${\delta}^{15}N$) are $6.2{\pm}1.1$‰ (ranging from -4.4‰ to -7.6‰, n=9). This is the first approach to analyse charred residues using stable isotopic method in Korea. Charred food residues on the interior surface of archaeological pottery can provide valuable information about pottery use and dietary habits of its population.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.373-376
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• 2006

본 연구의 목적은 동해 울릉분지의 제4기 후기 퇴적물 내의 유기물, 공극수와 메탄의 특징 및 상호작용을 규명하는데 있다. 연구지역에서 채취한 코어퇴적물을 원소 분석한 결과 C/N 및 C/S 비(wt. %)는 퇴적물 내 유기물이 주로 해양조류 기원을 가지고, 일반적인 해양 또는 정체 환경에서 퇴적되어Tdam을 지시한다. 그러나 Rock-Eval 열분석 결과는 유기물 기원이 육상식물(Type III)이고, 열적 성숙단계가 미성숙단계임을 보여준다. 이러한 원소분석과 열분석간의 상반된 결과는 유기물이 침강하는 동안 또는 퇴적 후 이루어진 강한 산화작용에 기인한 것으로 추정된다. 퇴적물 내 공극수의 황산염 농도가 퇴적물의 심도가 증가할수록 감소하며, 감소하는 경향은 크게 두 가지 (적선성, concave down)로 나누어진다. 이는 모든 코어에서 황산엽 환원작용이 일어나고 있음을 지시한다. 또한 직선선의 황산엽농도 구배는 무산소 메탄 산화작용(AMO)의 전형적인 특징이다. 황산염 농도의 수직적 구배를 이용하여 SMI(sulfate-methane interface) 심도를 계산하면, 남부울릉분지의 코어 (03GHP-01, 03GHP-02; <3.5mbsf)가 북부울릉분지 코어(01GHP-05, 01GHP-07, 03GHP-03, 03GHP-04, 03GHP-05; > 6mbsf)보다 낮은 값을 갖는다. 위와 같은 SMI 심도차는 메탄의 상부 분산량과 밀접한 관련있는 것으로 추정된다. 메탄가스의 탄소 안정동위원소 $({\delta}^{13}C)$ 분석값들은 -83.5%o에서 -69.5%o의 범위를 가지고 있고, 이산화탄소 환원작용($CO)_2$ reduction)에 의한 생물 (biogenic) 기원임을 지시한다.

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.444-452
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• 2012

We conducted a comprehensive monitoring for freshwater food web in a wetland system (Jangcheok Lake), from May to October, 2011. Monthly sampling for zooplankton, fish as well as organic matters, was implemented. In order to understand the food web structure and energy flow, we applied stable isotope analysis to the collected samples, based on ${\delta}^{13}C$ and ${\delta}^{15}N$ values of epiphytic particulate organic matter(EPOM) and particulate organic matter (POM), epiphytic and planktonic zooplankton, fish (Lepomis macrochirus). In the study site, epiphytic and planktonic zooplankton was 24 and 30 species, respectively, and coincidence species between epiphytic and planktonic zooplankton were 20 species. Epiphytic zooplankton were more abundant during the spring and early summer (May to July); however, planktonic zooplankton were more abundant during the autumn (September to October) season. Stable isotope analysis revealed that fish and epiphytic zooplankton had seasonal variations on their food sources. EPOM largely contributed epiphytic zooplankton in spring (May), but increasing contribution of POM in autumn (September) was detected. However, planktonic zooplankton depended on only POM in both seasons. Fish utilized both epiphytic and planktonic zooplankton, but small sized (1~3 cm), fish preferred epiphytic zooplankton, where as larger sized (4~7 cm) fish tended to consume planktonic zooplankton, and epiphytic zooplankton had important role in energy transfer. This pattern was clear when results of spring and autumn stable isotope analysis were compared. From the results of this study, we confirmed that wetlands ecosystem supported various epiphytic and planktonic zooplankton species, they depend on other food items, respectively. L. macrochirus also showed a difference of food source according to the body size, they depend on seasonal density change of zooplankton. In particular, epiphytic zooplankton was very important for growth and development of young fish in the spring.

• Journal of the Mineralogical Society of Korea
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• v.23 no.1
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• pp.1-13
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• 2010

The Yugeum deposit in Youngduk in Gyungsangbuk-do is emplaced in the Cretaceous granitoids located in the Northeastem Gyeongsang Basin. Gold-bearing quartz veins filling the fracture with a direction of $N19^{\circ}{\sim}38^{\circ}W$ are most abundantly distributed within the Younghae granodiorite body. The formation of quartz veins can be classified into three main stages: barren quartz stage, auriferous quartz vein stage, and finally the extensive sulfide mineralization stage. Various sulfide minerals such as pyrite, chalcopyrite, galena, sphalerite, and arsenopyrite were precipitated during the hydrothermal gold mineralization process. Gold commonly occurs as fine-grained electrum in sulfides with high Au concentration (up to 93 wt%) compared to Ag. During the early gold mineralization stage, the temperature and pressure of the fluids are in the range of $220{\sim}250^{\circ}C$ and 730~1800 bar, and the oxygen fugacity is between $10^{-27}$ and $10^{-31.7}$ atm. On the other hand, the fluids of the late stage mineralization are characterized by temperature of $290{\sim}350^{\circ}C$ and pressure of 206~472 bar, and the oxygen fugacity is in the range of $10^{-26.3}{\sim}10^{-28.6}$ atm. The sulfur isotope compositions of sulfide minerals are in the range of $0.2{\sim}4.2^{\circ}/_{\circ\circ}$, while the ${\delta}^{34}SH_2S$ values range from 1.0 to $3.7^{\circ}/_{\circ\circ}$. The Ag/Au atomic ratios of electrum ranges from 0.15 to 1.10, and Au content is higher than Ag in most electrum. During the main gold mineralization stage at the relatively high temperature condition and with pH from 4.5 to 5.5, the stability of ${AuCl_2}^-$ increased while the stability of ${Au(HS)_2}^-$ decreased. Considering the pressure estimated in this deposit, the temperature of the ore fluid reached higher than $350^{\circ}C$ and ${AuCl_2}^-$ became an important species for the gold transportation. As mineralization proceeded with decreasing temperature and increasing pH and $f_{o2}$, the precipitation of sulfide minerals and accompanying electrum occurred.

• Journal of Microbiology and Biotechnology
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• v.13 no.3
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• pp.415-421
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• 2003

A bacterium, Pseudomonas fluorescens 2112, that is antagonistic against a red-pepper blight-causing fungus, Phytophthora capsici, was isolated from the local soil of Gyongju, Korea. This strain formed an orange-colored clear halo zone on chrome azurol S (CAS) blue agar, suggesting the production of a siderophore in addition to an antifungal antibiotic. The optimal culture conditions for siderophore production by P. fluorescens 2112 were 30-h cultivation at $25^{\circ}C$ and pH 6.5 in King's B medium. The presence of $20{\mu}g/ml\;of\;Fe^3+$ ion or EDDHA promoted the production of siderophore in King's B medium. The siderophore was purified from culture broth by CM-Sephadex C-25 and Sephadex G-25 column chromatographies. The UV spectra of the purified siderophore was the same as that of pyoverdins or pseudobactins. The molecular mass was 1,958 Da determined by FAB-rlass spectrometer, and the amino acid composition analysis showed that the purified siderophore consisted of glycine/threonine/serine/glutamic acid/alanine/lysine with the molar ratio of 3:2:1:1:1:1, DL-Threo-${\beta}$-hydroxyaspartic acid and $N^{\delta}$-hydroxyornithine, two of the essential constituents of pyoverdin, were also found. The purified siderophore pyoverdin showed strong in vitro and in vivo antagonistic activities against phytophthora blight-causing P. capsici. Especially in an in vivo pot test, the siderophore protected red-pepper Capsicum annum L. very well from the attack of P. capsici. These results indicated that the purified siderophore of P. fluorescens 2112 played a critical role in the biocontrol of the red-pepper blight disease, equivalent to treatment by P.fluorescens 2112 cells.

• Journal of Sensor Science and Technology
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• v.13 no.2
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• pp.157-167
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• 2004

A stoichiometric mixture of evaporating materials for $CuAlSe_{2}$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $CuAlSe_{2}$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $680^{\circ}C$ and $410^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CuAlSe_{2}$ single crystal thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}cm^{-3}$ and $295cm^{2}/V{\codt}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuAlSe_{2}$ obtained from the absorption spectra was well described by the Varshni's relation, $E_{g}(T)$ = 2.8382 eV - ($8.68{\circ}10^{-4}$ eV/K)$T^{2}$/(T + 155 K). The crystal field and the spin-orbit splitting energies for the valence band of the $CuAlSe_{2}$ have been estimated to be 0.2026 eV and 0.2165 eV at 10 K, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}_{5}$ states of the valence band of the $CuAlSe_{2}$. The three photocurrent peaks observed at 10 K are ascribed to the $A_{1-}$, $B_{1-}$, and $C_{1-}$ exciton peaks for n = 1.

• Journal of the Korean Magnetics Society
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• v.17 no.1
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• pp.10-13
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• 2007

Single crystalline, $LuFe_2O_4$, was grown by the floating zone method. The crystal structure was a two-dimensional layered-type rhombohedral($R\={3}mh$) structure, with an $a_0=3.440(2)\;{\AA}\;and\;a\;c_0=25.263(2)\;{\AA}$. The magnetic $N\'{e}el$ temperature($T_N$) was determined to be 250 K. The $M\"{o}ssbauer$ spectrum at 12 K was fitted with four sextet sets which was resulted from the crystal structure. The spectrm at room temperature consisted of three singlets and a doublet with the electric quadrupole splitting. The isomer shift($\delta$) value of the singlet was $0.20{\pm}0.01mm/s$ relative to the Fe metal indicating the $Fe^{3+}$ valence state, and the value of the doublet was $0.70{\pm}0.01mm/s$ indicating $Fe^{2+}$. The $M\"{o}ssbauer$ absorption area ratio between $Fe^{3+}$ and $Fe^{2+}$ at room temperature was 1:1. The doublet phase of spectra gradually disappears by up to 360 K. At 360 K, the spectrum shows the singlet phase. We suggested that the spontaneous polarization effect of $LuFe_2O_4$ was caused by the change of iron behavior.

• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.175-184
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• 2013

Organic carbon and total nitrogen stable isotope ratios of suspended materials were determined at 3 stations (from Mongtan Bridge to Youngsan river estuary barrage) (n=6, each) from November 2008 to August 2009, in order to understand the origin of particulate organic matter at the Estuary of Youngsan River. Allochthonous organic matter, ammonia-N and silicate were increased after heavy rain (in August). Carbon isotope ratios were significantly different between stations in November and August, and it was possible to determine the origin of organic matter. The heavier nitrogen isotope ratios, as well as higher phosphate concentrations, were found in November than other sampling times. Livestock wastewater and farmland input was likely the main causes of these high values. In addition, YS3 station, the nearest site to estuary barrage, appears to be affected by a substantial amount of livestock wastewater and farmland input, considering that nitrogen isotope ratios were heavier than those at the upper sites. These results suggest that the analysis of stable isotope ratios is a simple but useful tool for the determination of organic matter origin in aquatic environments.