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RISS 인기검색어
- 검색키워드
- 저자 : ( Ki-jung Paeng ) (검색결과 95 건)
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Jung, Min-Woo,Kim, Ki-Pal,Cho, Byung-Yun,Paeng, Insook R.,Lee, Dai-Woon,Park, Young-Hun,Paeng, Ki-Jung Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.1
The commercially available Amberlite XAD-2 and XAD-4 resins were modified with macrocyclic protoporphyrin IX (PPIX) or tetrakis(p-carboxyphenyl) porphyrin (TCPP) to enhance the adsorption capacity for phenol and chlorophenols. The chemically modified polymeric adsorbents (XAD-2+PPIX, XAD-2+TCPP, XAD-4+PPIX, and XAD-4+TCPP) were applied to the solid phase extraction as an adsorbent material for the preconcentration of phenol and chlorophenols in environmental waters. Generally, the synthesized adsorbents showed higher recoveries than underivatized adsorbents, XAD-2 and XAD-4, without matrix interferences. Especially, XAD-4+PPIX showed more than 90% recoveries for all compounds used in this study including hydrophilic phenol. The major factor for the increase of the adsorption capacity was the increase of $\pi$-$\pi$ interaction between adsorbents and samples due to the introduction of the porphyrin molecule. However, the breakthrough volumes and recovery values of the XADs+TCPP columns were slightly decreased for the bulky chlorophenols such as TCP and PCP. Using molecular mechanics methods, the structures of TCPP and PPIX were compared with that of porphine, the parent molecule of porphyrin. Four bulky p-carboxyphenyl groups of TCPP were torsional each other, thus the molecular plane of TCPP were not on the same level. In conclusion, the decrease of breakthrough volumes and recovery values of XADs+TCPP columns for bulky phenols can be explained by the steric hindrance of the $\pi$-$\pi$ interaction between porphyrin plane and the phenols.
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Paeng, Ki-Jung,Lim, Chae-Yun,Lee, Bo-Young,Myung, No-Seung,Rhee Paeng, In-Sook Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.9
Stepwise dechlorination of 1,2,4-trichlorobenzene was observed at a glassy carbon electrode in dimethylformamide containing 0.1 M tetraethylammonium perchlorate. Especially, dechlorination to dichlorobenzene and further to monochlorobenzene or benzene was successfully demonstrated with a porous reticulated vitreous carbon electrode. Electrochemical dechlorination of polychlorobenzenes employing a flow cell with a reticulated vitreous carbon working electrode is also described. Preliminary experiments with a flow cell showed that dechlorination of trichlorobenzene to dichlorobenzene was partially completed while dechlorination to benzene or monochlorobenzene was not successful, suggesting that a flow rate and electrolysis time should be further optimized for the complete electrolysis.
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Selective Concentration and Determination of Phenol and Chlorophenols by Solid Phase Extraction
Jung, Min-Woo,Lee, Dai Woon,Paeng, Ki-Jung 한국분석과학회 1995 분석과학 Vol.8 No.4
This study employs the variety of mixtures of XAD resin and active carbons as concentration base for solid phase extraction (SPE) which has been widely used to preconcentrate and purify phenol and chlorophenols in determination of environmental water samples. In this study, we employed variety of mixtures of copolymer based XAD-4 resin with active carbons. This cartridges shows advantages of both materials, such as better affinity to phenol by active carbon and better mechanical stabilities from XAD resin. The better enrichment factor, pretreatment time, recoveries and limit of detection (LOD) were achieved by the attempts to pack precolumns with both meterials for preconcentration.
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Changes in urine androgen and prostaglandin levels during finasteride treatment
( Ki-hun Kim ),( Eun-ju Im ),( Mi-yeon Lee ),( Jeong-ae Lee ),( Ki-jung Paeng ),( Bong-chul Chung ),( Bark-lynn Lew ),( Woo-young Sim ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.2
Background: Male pattern baldness (MPB), an androgenic alopecia, is hair loss disease in which the hair gradually tapers, shortens, and falls off because of androgen and hereditary factors. The MPB mechanism which associated with dihydrotestosterone (DHT) and testosterone (T) is well known. As well as androgenic steroids, prostaglandins (PG) are also important role in hair growth and MPB. MPB patients also showed higher level of PG in hair. However there was no study about urine PG level change during finasteride treatment. Objectives: In this study, we investigated changes in urine androgen and PG level during finasteride treatment. Methods: We collected urine sample of ten MPB patients who treated with finasteride for 1 year and ten normal healthy males for control group. And we analyzed T, DHT, EpiT, DHEA, and PGs in urine sample by ultra-high-performance liquid chromatography-tandem mass spectrometry. Results: The urinary androgen and prostaglandin levels were not significantly different between the two groups. MPB patients usually have high levels of androgen and PG levels, but finasteride treatment reduces the levels of androgen and PG to similar levels as the healthy control group Conclusion: This study confirmed that finasteride treatment reduced urinary PG to normal levels. And with further studies about PGs, it is expected that urine PGs can be used as a marker for confirmation of finasteride therapeutic effect.
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Jung, Hyo-Jin,Lee, Myong-Euy,Lim, Chae-Yun,Paeng, Ki-Jung Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.1
The potentiometric responses for various anions are investigated with membrane electrode (membrane 1) based on 1,3-diethyl-1,3-dihydroxy-1,3-bis(2-dimethylaminomethyl ferrocenyl) disiloxane. The nitrate ion-selective electrode based on compound 1 gave a good Nernstian response of 58.18 mV per decade for nitrate with the detection limit of −e5.66 of log [NO3−e]. Compound 1 has all those functional groups and the other two compounds have less functional group of ferrocenyl or ferrocenyl and hydroxide, respectively. Even though, potentiometric response to anions was excellent at pH 5, the selectivity pattern for all three membrane electrode based on series of disiloxane is almost like Hofmeister sequence at pH 5. However, the membrane electrode 1-3 exhibited very different response to anions at pH 7. In this pH, NH2 is not protonated and ionophore may act as neutral carrier. Hydrogen bond may enhance the responsibility to hydrogen acceptors and intramolecular electro-active site may increase the permeability of analyte to ionophore in membrane.
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Jung, Young Jun,Chi, Yong Hun,Chae, Ho Byoung,Shin, Mi Rim,Lee, Eun Seon,Cha, Joon-Yung,Paeng, Seol Ki,Lee, Yuno,Park, Jin Ho,Kim, Woe Yeon,Kang, Chang Ho,Lee, Kyun Oh,Lee, Keun Woo,Yun, Dae-Jin,Lee, Biochemical Society 2013 Biochemical journal Vol.456 No.1
<P>Multiple isoforms of Arabidopsis thaliana h-type thioredoxins (AtTrx-hs) have distinct structural and functional specificities. AtTrx-h3 acts as both a disulfide reductase and as a molecular chaperone. We prepared five representative AtTrx-hs and compared their protein structures and disulfide reductase and molecular chaperone activities. AtTrx-h2 with an N-terminal extension exhibited distinct functional properties with respect to other AtTrx-hs. AtTrx-h2 formed low-molecular-mass structures and exhibited only disulfide reductase activity, whereas the other AtTrx-h isoforms formed high-molecular-mass complexes and displayed both disulfide reductase and molecular chaperone activities. The domains that determine the unique structural and functional properties of each AtTrx-hs protein were determined by constructing a domain-swap between the N- and C-terminal regions of AtTrx-h2 and AtTrx-h3 (designated AtTrx-h-2N3C and AtTrx-h-3N2C respectively), an N-terminal deletion mutant of AtTrx-h2 [AtTrx-h2-N(?19)] and site-directed mutagenesis of AtTrx-h3. AtTrx-h2-N(?19) and AtTrx-h-3N2C exhibited similar properties to those of AtTrx-h2, but AtTrx-h-2N3C behaved more like AtTrx-h3, suggesting that the structural and functional specificities of AtTrx-hs are determined by their C-terminal regions. Hydrophobicity profiling and molecular modelling revealed that Ala100 and Ala106 in AtTrx-h3 play critical roles in its structural and functional regulation. When these two residues in AtTrx-h3 were replaced with lysine, AtTrx-h3 functioned like AtTrx-h2. The chaperone function of AtTrx-hs conferred enhanced heat-shock-resistance on a thermosensitive trx1/2-null yeast mutant.</P>
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