• Title/Summary/Keyword: DAG

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Synthesis of Mono-,Diacylglycerol from Rice Bran Oil using lipase and Separation by Fractionation

  • Kim, Song-Hyun;Lee, Ki-Teak
    • Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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    • 2003.10a
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    • pp.142.1-142
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    • 2003
  • Mono-, diacylglycerol were synthesized by glycerolysis of bran oil and glycerol using IM60 (an immobilized lipase) in a stirred batch reactor for 72 hours. After glycerolysis, the composition TAG, DAG, MAG in product was 41.7%, 44.7%, and 11.1%, respectively. Glycerol was separated, then this mixture product was undergone fractionation for winterization followed. The fractionation was performed using hexane and acetone solvent to reduce palmitic acid at the low temperature for overnight individually. Temperature was set -40$^{\circ}C$, -14$^{\circ}C$, -8$^{\circ}C$ and 0$^{\circ}C$, respectively. By considering results from this experiments, fractionation with hexane at -8$^{\circ}C$ was most efficient regarding to yield without crystallization.

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Monoacylglycerol O-acyltransferase 1 (MGAT1) localizes to the ER and lipid droplets promoting triacylglycerol synthesis

  • Lee, Yoo Jeong;Kim, Jae-woo
    • BMB Reports
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    • v.50 no.7
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    • pp.367-372
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    • 2017
  • Monoacylglycerol acyltransferase 1 (MGAT) is a microsomal enzyme that catalyzes the synthesis of diacylglycerol (DAG) and triacylglycerol (TAG). However, the subcellular localization and catalytic function domain of this enzyme is poorly understood. In this report, we identified that murine MGAT1 localizes to the endoplasmic reticulum (ER) under normal conditions, whereas MGAT1 co-localize to the lipid droplets (LD) under conditions of enriching fatty acids, contributing to TAG synthesis and LD expansion. For the enzyme activity, both the N-terminal transmembrane domain and catalytic HPHG motif are required. We also show that the transmembrane domain of MGAT1 consists of two hydrophobic regions in the N-terminus, and the consensus sequence FLXLXXXn, a putative neutral lipid-binding domain, exists in the first transmembrane domain. Finally, MGAT1 interacts with DGAT2, which serves to synergistically increase the TAG biosynthesis and LD expansion, leading to enhancement of lipid accumulation in the liver and fat.

Fault-Tolerant Adaptive Routing : Appying SCP to RIFP in Mesh Multicomputers (적응적 오류 허용 라우팅 : 매쉬 구조에서의 SCP를 적용한 RIFP)

  • 정성우;김성천
    • Proceedings of the Korean Information Science Society Conference
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    • 2001.04a
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    • pp.712-714
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    • 2001
  • 매쉬 구조를 갖는 다중 프로세서에서의 오류를 허용하는 라우팅 기법은 구현에 있어 간결함을 제공하는 환경으로, 다수의 오류를 허용하기 위해 직사각형 모양의 오류 블록으로 구성하여 라우팅을 수행한다. 이 경우, 블록 내부의 정상적인 노드 역시 오류 노드로 간주되어 전체 노드의 사용율을 저하시키는데, 오류 블록을 몇 개의 확장된 매쉬로 나누고 DAG(Directed Acyclic Graph)에 적용하여 메시지 전송의 최단 거리를 구하는 RIFP(Routing for Irregular Faulty Pattern)기법으로 이를 해결하였다. 그러나, 이 기법은 노드간에 주고받는 메시지가 거치는 hop의 수가 오히려 증가되는 문제가 발생하게 된다. 본 논문에서는 증가되는 hop의 수를 억제하기 위해 목적 노드와 이웃 노드들로부터 오류블록 경계 부분까지 직선 경로를 찾는 SCP(Short-Cut Path)를 적용한 RIFP를 제안한다.

Web API Discovery and Composition Techniques (Web API 발견 및 조합 기법)

  • Lee, Yong-Ju
    • Proceedings of the Korea Information Processing Society Conference
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    • 2014.04a
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    • pp.960-963
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    • 2014
  • 최근 매쉬업에 대한 관심도가 매우 높아짐에 따라 수많은 Web API들이 생성되고 있다. 이런 Web API들을 매쉬업 속으로 결합할 때 여러 가지 이슈들이 존재한다. 특히, 수많은 API들이 매쉬업 개발자에 의해 수동으로 조합될 때 이는 더욱 심각해진다. 본 논문에서는 Web API 발견 및 조합을 위한 하나의 새로운 기법을 제안한다. 제안된 발견 기법은 질의를 만족시키지 못하는 API들을 재빨리 필터링 시키는 전략을 수립한다. API 조합 기법은 발견 기법을 확장/발전시켜 Web API 입출력 사이의 시맨틱 유사도를 기반으로 하고, 원하는 목표를 만족하는 출력을 산출할 수 있는 사이클 없는 방향성 그래프(DAG)를 생성한다. 또한, Web API 발견 및 조합을 효율적으로 생성하기 위해 본 논문에서는 Web API 발견 및 조합 시스템을 구현한다.

Simulation of the Solution EPR Spectra of Mixed-Valence Heteropolyanions Containing Vanadium(IV) and Vanadium(V)$^\dag$

  • So, Hyun-Soo;Lee, Chul-Wee;Lee, Duck-Hwan
    • Bulletin of the Korean Chemical Society
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    • v.8 no.5
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    • pp.384-388
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    • 1987
  • Modified Bloch equations were used to simulate the solution EPR spectra of mixed-valence heteropolyanions containing vanadium(IV) and vanadium(V). Simulated are the 15-, 22-, 36- and 43-line spectra of $\alpha$-1,2-$[PV(IV)VW_{10})O_{40}]^{6-},\;[P_2V(IV)V_2W_{15}O_{62}]^{10-},\;[HP_2V(IV)V_2W_{15}O_{62}]^{9-}$ and $\alpha$-1,2,3-$[HSiV(IV)V_2W_9O_{40}]^{7-}$, respectively. The transition probabilities for the intramolecular electron transfer were determined from the simulations.

Geometries and Energies of S$_N$2 Transition States$^\dag$

  • Lee, Ik-Choon;Kim, Chan-Kyung;Song, Chang-Hyun
    • Bulletin of the Korean Chemical Society
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    • v.7 no.5
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    • pp.391-395
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    • 1986
  • MNDO calculations were carried out to determine reactant complexes and transition states of the $S_N2$ reactions of $CH_3X\;+\;Y^-\;{\to}\;CH_3Y\;+\;X^-$ where X = F, Cl, CN and Y = CN, OH, F, Cl. The leaving group ability was found to vary inversely with the activation barrier, which in turn was mainly ascribable to the deformation energies accompanied with bond stretching of C-X bond and inversion of $CH_3$ group. The nucleophilicity was shown to be in the order $Cl^->F^->OH^->CN^-$ but the effect on the activation barrier was relatively small compared with that of the leaving group. The bond breaking and bond formation indices and energy decomposition analysis showed that the TS for the reaction of $CH_3$Cl occurs in the early stage of the reaction coordinate relative to that of $CH_3$F. It has been shown that the potential energy surface (PES) diagrams approach can only accommodate thermodynamic effects but fails to correlate intrinsic kinetic effects on the TS structure.

Construction of a Dynamic Laser Light Scattering System Using a Personal Computer$^\dag$

  • Kim, Myung-Joong;Lee, Sang-Yong;Chung, Koo-Soon;Lee, Hoo-Sung
    • Bulletin of the Korean Chemical Society
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    • v.8 no.5
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    • pp.403-405
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    • 1987
  • A dynamic laser light scattering system has been constructed using a personal computer. The intensity of the scattered light was detected with a photomultiplier tube and a photon counter. The BCD output of the photon counter which is proportional to the intensity of scattered light is fed into a personal computer via an interface card. The personal computer was programmed as an autocorrelator in machine language. The data acquisition rate of the system was about 600 samples/s which is adequate for studies on the molecular dynamics of concentrated polymer solutions, polymer latices with large particle size, and polymer glass systems. The constructed system was tested with polystyrene latex and the measured diameter of the latex particle agrees well with the supplier's value.

Theoretical Studies of Solvent Effects on Gas Phase Reactions of Methoxide Ion with Substituted Ethylenes$^\dag$

  • Lee, Ik-Choon;Lee, Bon-Su;Won Jong-Ok
    • Bulletin of the Korean Chemical Society
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    • v.8 no.6
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    • pp.444-449
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    • 1987
  • Solvent effects on gas phase reactions of methoxide ion with substituted ethylenes, $CH_2$ = CHR where R = CN, CHO and $NO_2$, are investigated theoretically using the AM1 method. Results show that the methoxide approaches in-plane in all reactions, but subsequently rotate out-of-plane to form tetrahedral complexes in additon reactions. All reactions of a bare methoxide are found to be exothermic, the exothermicity being the greatest in the ${\beta}$-addition, in which the excess energy is forced to be contained within the ${\beta}$-adduct rendering extreme instability. However a part of the excess energy can be removed by a solvate molecule giving a stable complex prior to the product formation. The hydride transfer processes were found to be unfavorable due to the high activation barriers. The ${\alpha}-H^+$ abstraction process from acrylonitrile becomes endothermic as a result of monosolvation of the methoxide, in agreement with experimental results.

Kinetics and Mechanism of $N_2H_4-KBrO_3$ Reaction in the Presence of Allyl Alcohol$^\dag$

  • Choi, Q.-Won;Chung, Keun-Ho
    • Bulletin of the Korean Chemical Society
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    • v.7 no.6
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    • pp.462-465
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    • 1986
  • Kinetics and Mechanism of $N_2H_4-KBrO_3$ reaction in the presence of allyl alcohol have been studied. The pseudo-first order rate constant for gas evolution was found to be $10^{-4}{\sim}10^{-2}\;sec^{-1}\;at\;25.0{\pm}0.1^{\circ}C$, increasing with concentration of hydrogen ion. When concentrations of sulfuric acid and allyl alcohol are both sufficiently high, the following overall reaction explains experimental results reasonably well: $N_2H_4\;+\;BrO_3^-\;+\;H^+\;{\to}\;N_2\;+\;HOBr\;+\;2H_2O,\;CH_2\;=\;CHCH_2OH\;+\;HOBr\;{\to}\;CH_2-OHCHBrCH_2OH$. More complicated reaction mechanisms at lower acidity conditions have been contemplated.

Turbidimetric and Nephelometric Studies on Aggrregation of Cationic-Anionic Surfactants$^\dag$

  • Park, Joon-Woo;Chung, Myung-Ae;Ahn, Byung-Tae;Lee, Hoo-Sung
    • Bulletin of the Korean Chemical Society
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    • v.8 no.6
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    • pp.462-465
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    • 1987
  • The aggregation between cationic and anionic surfactants was studied by turbidimetric and nephelometric methods with emphasis on facile analysis of the surfactants and understanding of the mixed micellization. The turbidimetric titration of sodium dodecylsulfate (SDS) with cetyltrimethylammonium bromide (CTAB) or cetylpyridinium bromide (CPB) showed maximum turbidity at equimolar composition in the SDS concentration range of 0.1-0.9 mM. The nephelometric titration of the same systems extended the limit of analysis to 0.001 mM. The sodium salts of decylsulfate and sulfonate gave similar maxima, but not at equimolar composition. The coexistence of equimolar aggregates and mixed micelles were shown over broad composition range. The aggregation and mixed micellization of the anionic/cationic surfactants mixtures depended sensitively on the hydrophobic character of the surfactants.