• BMB Reports
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• 제38권6호
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• pp.633-638
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• 2005

Biosynthesis of prostanoids is regulated by three sequential enzymatic steps, namely phospholipase $A_2$ enzymes, cyclooxygenase (COX) enzymes, and various lineage-specific terminal prostanoid synthases. Prostaglandin E synthase (PGES), which isomerizes COX-derived $PGH_2$ specifically to $PGE_2$, occurs in multiple forms with distinct enzymatic properties, expressions, localizations and functions. Two of them are membrane-bound enzymes and have been designated as mPGES-1 and mPGES-2. mPGES-1 is a perinuclear protein that is markedly induced by proinflammatory stimuli, is down-regulated by anti inflammatory glucocorticoids, and is functionally coupled with COX-2 in marked preference to COX-1. Recent gene targeting studies of mPGES-1 have revealed that this enzyme represents a novel target for anti-inflammatory and anti-cancer drugs. mPGES-2 is synthesized as a Golgi membrane-associated protein, and the proteolytic removal of the N-terminal hydrophobic domain leads to the formation of a mature cytosolic enzyme. This enzyme is rather constitutively expressed in various cells and tissues and is functionally coupled with both COX-1 and COX-2. Cytosolic PGES (cPGES) is constitutively expressed in a wide variety of cells and is functionally linked to COX-1 to promote immediate $PGE_2$ production. This review highlights the latest understanding of the expression, regulation and functions of these three PGES enzymes.

• 대한화학회지
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• 제25권4호
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• pp.253-262
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• 1981

AgI/PVC${\cdot}$THF막전극은 단일할로겐화이온과 할로겐화이온 혼합물을 질산은표준용액으로 전위차법적정할 때 지시전극으로 사용될 수 있다. 그러나 할로겐화이온혼합물을 단계적정할 때 오차가 매우 큼을 알 수 있었다. 그러나 적정용액에 $NaNO_3$나 $Ba(NO_3)_2$같은 뭉침제를 가하면 오차가 매우 감소한다. 또한 젤라틴과 거름종이의 효과 그리고 온도의 영향도 조사하였다.

• 한국물환경학회지
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• 제22권6호
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• pp.1052-1059
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• 2006

For monitoring the fecal pollution at Nak-Dong River, one of the eutrophicated rivers, the differences between total coliforms (TC) and fecal coliforms (FC) using both of membrane filtration (MF)/MPN method, and also fecal streptococcus (FS) by MF-method was investigated. To evaluate the correlation between TC, FC, and FS statistical analyses were performed by using Minitab. And a part of the presumptive TC/FC and background colonies was purified and identified using API 20E kit (Biomeriux). As results, most (89%) of presumptive FC by MF was identified as Escherichia coli while only 14% (MPN) and 11% (MF) of TC were identified as E. coli. Furthermore, FC by MF was correlated significantly with other fecal indicators (TC/FS by MF and FC by MPN), while TC by MPN was not correlated with any other indicators. Thus, the detection of FC by MF-method may be the most reasonable for monitoring the fecal pollution.

• 공업화학
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• 제21권5호
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• pp.481-487
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• 2010

최근 에너지 효율이 높은 공정기술의 수요가 증가하면서 분리막을 이용한 기체분리가 많은 연구자들의 관심을 모으고 있다. 현재 분리막에 의한 기체 분리 시장은 고분자막이 독점하고 있으며 탄화수소와 같은 응축기체 분리시장이 휠씬 큼에도 불구하고 주로 비응축 기체분리에 제한되고 있다. 이는 고분자 재료의 물성에 한계가 있기 때문이다. 제올라이트막이나 제올라이트/고분자 복합막이 제올라이트의 우수한 분리력과 화학적/열적 특성으로 인해 고분자막의 한계를 극복할 수 있는 대안이 될 수 있다. 이번 총설에서는 이러한 기체분리를 위한 제올라이트막과 제올라이트/고분자 복합막에 대해 간략히 소개하고자 한다.

• 공업화학
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• 제20권6호
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• pp.700-704
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• 2009

본 연구에서는 다공성 탄소전극의 내부 전해질 농도에 따른 전극의 전기화학적 특성 변화를 연구하였다. 다공성 탄소전극의 내부를 0.01, 0.05, 0.1, 0.5 M KCl 용액으로 채우고 양이온교환막을 결합한 후 cyclic voltammetry, chronoamperometry, impedance spectroscopy 분석을 실시하였다. 실험결과 전극의 특성은 전극 내부의 전해질 농도에 따라 큰 차이를 보였으며 농도가 높을수록 전극 내부의 charging 저항이 감소하여 전기용량이 크게 증가하는 것을 알 수 있었다. 실험결과로부터 이온교환막을 결합한 축전식 탈염공정에서 전극 내부의 전해질 농도를 높임으로써 저 농도의 염수를 효과적으로 탈염할 수 있을 것으로 기대된다.

• 공업화학
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• 제19권2호
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• pp.205-208
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• 2008

저가인 aromatic elastomer polymer인 polySEBS와 PS의 방향족 작용기에 술폰기를 도입시킴으로써 sulfonated polySEBS과 sulfonated PS를 얻었다. 이 술폰화된 고분자를 활용하여 고분자 전해질 연료전지의 이온 교환막으로 사용될 수 있는 새로운 sulfonated polySEBS/sulfonated PS blending films를 제조하였다. 이 필름들의 수소이온 전도도는 sulfonated polySEBS와 sulfonated PS의 혼합비에 따라 $10^{-2}{\sim}10^{-3}S/cm$로 다양하게 나타났다. 특히, sulfonated polySEBS 10.0 g에 sulfonated PS를 0.5 g 첨가하여 제조한 film이 0.75 meq/g의 이온교환용량 및 25%의 함수율과 함께 가장 우수한 0.07 S/cm의 이온전도도를 나타냈다.

• 한국세라믹학회지
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• 제50권6호
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• pp.451-453
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• 2013

Porous ceramic membranes consisting of $Ce_{1-x}Y_xO_{2-{\delta}}$ were developed for hydrogen permeation tests. Various amounts (x = 0, 0.05, 0.1, 0.2) of yttrium were doped to ceria to study the effect of yttrium doping on ceria membranes on various properties, including hydrogen permeability. $Ce_{1-x}Y_xO_{2-{\delta}}$ powder was synthesized by the sol-gel method. These membranes were fabricated by pressing and sintering at $1300^{\circ}C$ for 6 h. As the amount of yttrium increased, the grain size of the membrane decreased. Hydrogen permeability was improved as the yttrium content increased. Selective permeability of hydrogen compared to CO is explained by electric conductivity. As the temperature rose, both the hydrogen perm-selectivity and electric conductivity on $Ce_{0.8}Y_{0.2}O_{1.9}$ improved.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권4호
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• pp.165-170
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• 2005

A series of inorganic-organic hybrid membranes were prepared with a systematic variation of titanium dioxide nanoparticle content. Their water uptake, methanol permeability and proton conductivity as a function of temperature were investigated. The results obtained show that the inorganic oxide network decreases the proton conductivity and water swelling. It is also found that increase in inorganic oxide content leads to decrease of methanol permeability. In terms of the morphology, membranes are homogeneous and exhibit good adhesion between inorganic domains and the polymer matrix. The properties of the composite membranes are compared with the standard nafion membrane.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2229-2237
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• 2012

The two chelates based on calix[4]arene and thiacalix[4]arene have been synthesized and used as neutral ionophores for preparing PVC based membrane sensor selective to $Ho^{3+}$ ion. The addition of potassium tetrakis(4-chlorophenyl)borate (KTpClPB) and various plasticizers, viz., NDPE, o-NPOE, DOP, TEP and DOS have been found to improve significantly the performance of the sensors. The best performance was obtained with the sensor no. 6 having membrane of $L_2$ with composition (w/w) ionophore (2%): KTpClPB (4%): PVC (37%): NDPE (57%). This sensor exhibits Nernatian response with slope $21.10{\pm}0.3mV/decade$ of activity in the concentration range $3.0{\times}10^{-8}-1.0{\times}10^{-2}M\;Ho^{3+}\;ion$, with a detection limit of $1.0{\times}10^{-8}M$. The proposed sensor performs satisfactorily over a wide pH range of 2.8-10, with a fast response time (5 s). The sensor was also found to work successfully in partially non-aqueous media up to 25% (v/v) content of methanol, ethanol and acetonitrile, and can be used for a period of 4 months without any significant drift in potential. The electrode was also used for the determination of $Ho^{3+}$ ions in synthetic mixtures of different ions and the determination of the arsenate ion in different water samples.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2320-2324
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• 2012

A novel approach for metabolite extraction and fingerprinting was introduced based upon the nano-baskets and emulsion liquid membrane-nuclear magnetic resonance (ELM-NMR) technique. The objective of this method is optimizing the fingerprints, minimizing the metabolic variation from analysis, increasing the likelihood differences, and obtaining the maximum extraction yield. Low molecular weight metabolites in rat serum were recovered by ELMs using 12 nano-baskets of calixarene, as both emulsifier and carrier. The yields of ELMs were optimized by the method of one-at-a-time. According to NMR data, the maximum metabolic variation was achieved using scaffold 4 (4 wt %), n-decane membrane, stirring rate of 300 rpm, treat and phase ratios of 0.3 and 0.8, respectively. The results revealed that some calixarenes tend to extract non-specific macromolecules; and repeatability of fingerprints for 7-mediated ELM was maximum and for 3-mediated ELM was minimum. The yield of extractions was obtained to be higher for n-decane and lower for carbon tetrachloride. Among different membranes, the fingerprints by chlorinated liquid membranes were more repeatable than using toluene or n-decane.