Dimerization of HCN in the gas phase: A theoretical mechanistic study

Yim, M.K.,Choe, J.C. North Holland ; Elsevier Science Ltd 2012 Chemical physics letters Vol.538 No.-

Potential energy surfaces for the formation of covalently bound HCN dimers from two molecules of HCN or HNC were determined from CBS-QB3/APNO calculations. Several novel pathways, with and without the aid of protons, were found for the formation of iminoacetonitrile (HN?CHCN), an intermediate in adenine synthesis from HCN by oligomerization. Covalent C-C or C-N bonds between the two monomers were formed after rearrangement of bimolecular complex intermediates. Energetic and kinetic analyses suggest that the proton-catalyzed dimerizations substantially lower reaction barriers but cannot occur efficiently under interstellar conditions.

Quench behavior of superconductors during the operation of superconductor-triggered fault current limiters

Yim, S.W.,Park, C.R.,Yu, S.D.,Kim, H.R.,Hyun, O.B.,Sim, J.,Park, K.B.,Oh, I.S. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15

In the first-peak non-limiting type superconductor-triggered fault current limiter (STFCL), which was developed by the collaborative work of KEPRI and LSIS, the first half cycle of fault currents is passed, unlimited. Due to these characteristics, information needed for the fault judgments can be provided to the protection relays, which is useful for the protective coordination of power system. In this fault current limiter, superconductors are used as a fault detector that does not generate resistive loss in normal operation state. Therefore, high J<SUB>c</SUB> and fast occurrence of large resistance are the essential properties of superconductors for the application to fault detectors. In this study, for the design of superconducting fault detector (SFD), we investigated the quench behavior of two kinds of superconductors, stabilizer-free coated conductors (SF-CC) and Au/YBCO/sapphire substrate, during the operation of the first-peak non-limiting type STFCL. The dimension of SF-CC was 12mm widex1000mm long and that of Au/YBCO/sapphire was 20mm widex100mm long. Their critical current (I<SUB>c</SUB>) values were 250A and 200A, respectively, and the critical temperature (T<SUB>c</SUB>) was both 90K for both superconductors. When fault currents of over 3kA were applied, the STFCL carried out the current limitation successfully. At the beginning of the quench, SF-CC generated a resistance of 150mΩ, and 394mΩ was generated in the Au/YBCO/sapphire substrate, when 150V<SUB>rms</SUB> was applied. After the first half cycle, the resistance of the superconductors increased up to 263mΩ, and 846mΩ, respectively, and the temperature reached 132K and 127K. In addition, we also investigated the recovery characteristics of the SFDs. The SF-CC and Au/YBCO/sapphire substrate recovered the superconductivity by 353ms and 357ms, respectively. Based on the results of the analysis, we determined the required length of the superconductors for the SFD application.

Analysis of differential protein expression by cisplatin treatment in cervical carcinoma cells

YIM, E.-K.,LEE, K.-H.,KIM, C.-J.,PARK, J.-S. BMJ 2006 International journal of gynecological cancer Vol.16 No.2

<P>Cisplatin (cis-diaminedichloroplatinum), a DNA-damaging agent, which readily induces apoptosis in vitro, is one of the widely used anticancer drug in the treatment of human malignancies. Cisplatin has played an important role in cervical cancer management for effective chemotherapeutic regimen, but the underlying mechanisms inducing cell death at protein level are unknown. Using proteome analysis, an investigation aimed at a better understanding of the antiproliferative mechanisms by cisplatin was carried out in HeLa cervical carcinoma cells. In total, 21 protein spots were found to be differentially expressed following cisplatin treatment, of which 12 were upregulated (eg, regulator of G-protein signaling, TRAF:TNF (tumor necrosis factor) receptor-associated factor-interacting protein [I-TRAF], and cyclin-dependent kinase inhibitor p27 [p27(kip1)]) and 9 were downregulated (eg, myc proto-oncoprotein [c-myc] and proliferating cell nuclear antigen). Interestingly, we found the upregulation of proliferating cell nuclear antigen, which used molecular marker in cervical cancer screening. On the basis of proteomic data, we showed that cisplatin induced TRAF2-mediated NF-kappaB downregulation. In addition, our study demonstrated that cisplatin induced membrane death receptor-mediated and mitochondria-mediated apoptosis pathway. Our findings may offer new insights into the antiproliferative mechanism by cisplatin and its mode of action in cervical carcinoma cells.</P>

A short C-terminal tail prevents mis-targeting of hydrophobic mitochondrial membrane proteins to the ER

Reithinger, J.H.,Yim, C.,Park, K.,Bjorkholm, P.,von Heijne, G.,Kim, H. North-Holland Pub ; Elsevier Science Ltd 2013 FEBS letters Vol.587 No.21

Sdh3/Shh3, a subunit of mitochondrial succinate dehydrogenase, contains transmembrane domains with a hydrophobicity comparable to that of endoplasmic reticulum (ER) proteins. Here, we show that a C-terminal reporter fusion to Sdh3/Shh3 results in partial mis-targeting of the protein to the ER. This mis-targeting is mediated by the signal recognition particle (SRP) and depends on the length of the C-terminal tail. These results imply that if nuclear-encoded mitochondrial proteins contain strongly hydrophobic transmembrane domains and a long C-terminal tail, they have the potential to be recognized by SRP and mis-targeted to the ER.

Triclosan (TCS) and Triclocarban (TCC) cause lifespan reduction and reproductive impairment through oxidative stress-mediated expression of the defensome in the monogonont rotifer (Brachionus koreanus)

Han, J.,Won, E.J.,Hwang, U.K.,Kim, I.C.,Yim, J.H.,Lee, J.S. Elsevier Science 2016 COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY C-TOXICOLO Vol.185 No.-

Triclosan (TCS) and Triclocarban (TCC) are used as antimicrobial agents and have been widely dispersed and detected in the marine environment. However, the toxicities of TCS and TCC have been poorly investigated in marine invertebrates. In this study, the effects of TCS and TCC on mortality, population growth, lifespan, and fecundity were examined in the monogonont rotifer (Brachionus koreanus) using cellular ROS levels, GST enzymatic activity, and gene expression of defensomes. The median lethal concentration (LC50) of TCS (393.1μg/L) and TCC (388.1μg/L) was also determined in the same species. In TCS- and TCC-exposed B. koreanus, growth retardation and reduced fecundity were observed and were shown to have a potentially deleterious effect on the life cycle of B. koreanus. In addition, time-dependent increases in ROS content (%) and GST enzymatic activity were shown in response to TCS and TCC exposure. Additionally, transcript levels of detoxification proteins (e.g., CYPs), antioxidant proteins (e.g., GST-sigma, Cu/ZnSOD, CAT), and heat shock proteins (Hsps) were modulated in response to TCS and TCC exposure over a 24h period. Our results indicate that TCS and TCC induce oxidative stress and transcriptional regulation of detoxification, antioxidant, and heat shock proteins, resulting in changes in lifespan and fecundity.

Bioaccessibility of AhR-active PAHs in sediments contaminated by the Hebei Spirit oil spill: Application of Tenax extraction in effect-directed analysis

Hong, S.,Yim, U.H.,Ha, S.Y.,Shim, W.J.,Jeon, S.,Lee, S.,Kim, C.,Choi, K.,Jung, J.,Giesy, J.P.,Khim, J.S. Pergamon Press 2016 CHEMOSPHERE - Vol.144 No.-

Bioaccessibility of toxic substances in sedimentary residual oil is a crucial factor that needs to be considered for accurate risk assessments posed by oil spills. However, information on oil weathering processes and bioaccessibility of residual oil is often not sufficient and clear. In the present study, bioaccessibility of aryl hydrocarbon receptor (AhR)-active polycyclic aromatic hydrocarbons (PAHs) in coastal sediments near the site of the Hebei Spirit oil spill (Korea, 2007) was assessed by Tenax extraction in effect-directed analysis (EDA). Sediment samples collected 6 years after the oil spill were extracted using Soxhlet or Tenax, and EDA was performed using a battery of H4IIE-luc bioassay and GC/MSD analysis. Concentrations of PAHs and alkyl-PAHs in Soxhlet extracts ranged from 210 to 53,000 μg kg<SUP>-1</SUP> dry mass. However, concentrations of PAHs and alkyl-PAHs in Tenax extracts were approximately 20-fold less compared to those in Soxhlet extracts. In Soxhlet and Tenax extracts, the major AhR-active PAHs were identified as C1-chrysene, C3-chrysene, and C4-phenanthrene. Concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TEQ<SUB>PAHs</SUB>) explained 31% and 60% of the bioassay-derived TCDD-EQ concentrations in Soxhlet and Tenax extracts, respectively. Overall, bioaccessibility of PAHs and alkyl-PAHs in sedimentary residual oils depended on hydrophobicity (log K<SUB>ow</SUB>) and degree of weathering of crude oil. The results of the present study provide further evidence in support of the biological and ecological recoveries of oil spill sites.

Physical and Electrical Characteristics of Atomic-Layer-Deposited Hf-Silicate Thin Films Using Hf[N(CH3)(C2H5)]4 and SiH[N(CH3)2]3 Precursors

정권범,조만호,C. J. Yim,황정남,고대홍,J.-H. Lee,M. J. Kim,N. I. Lee,Y.-S. Kim 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.4

Hf-silicate films were grown by using atomic layer deposition with Hf[N(CH3)(C2H5)]4 and SiH[N(CH3)2]3 precursors. The composition of the Hf-silicate films was excellently well controlled by using the ratio of the deposition cycles of HfO2 and SiO2 (Hf/Si). The physical and the electrical characteristics of the Hf-silicate films were compared for Hf/Si = 3/1, Hf/Si = 1/1, and Hf/Si = 1/3. The relative Hf/(Hf+Si) compositions were 58 %, 41 %, and 25 % for Hf/Si = 3/1, Hf/Si = 1/1, and Hf/Si = 1/3, respectively. The binding characteristics of the Hf-silicate films were shifted in the direction of higher binding energy with increasing of SiO2 portion, resulting in electric charging. The molecular structure of the Hf-silicate films was changed by the relative compositions of HfO2 and SiO2. In addition, the dielectric characteristics of the Hf-silicate films were directly proportional to the HfO2 portion.

Metformin ameliorates acetaminophen hepatotoxicity via Gadd45β-dependent regulation of JNK signaling in mice

Kim, Y.H.,Hwang, J.H.,Kim, K.S.,Noh, J.R.,Choi, D.H.,Kim, D.K.,Tadi, S.,Yim, Y.H.,Choi, H.S.,Lee, C.H. Elsevier Science Publishers 2015 Journal of hepatology Vol.63 No.1

Background & Aims: Acetaminophen (APAP) overdose is a leading cause of drug-induced acute liver failure. Prolonged c-Jun N-terminal kinase (JNK) activation plays a central role in APAP-induced liver injury and growth arrest, and DNA damage-inducible 45 beta (Gadd45β) is known to inhibit JNK phosphorylation. Metformin has recently been shown to have hepatoprotective effects. The aim of the present study is to investigate whether metformin mitigates APAP-induced hepatotoxicity and to ascertain the molecular basis of this effect. Methods: We used APAP- and/or metformin-treated Gadd45β knockout (KO) mice and wild type (WT) C57BL/6J control mice. Primary mouse hepatocytes were isolated from WT and Gadd45β KO mice were used for in vitro study. Results: Metformin pretreatment protected against APAP toxicity with decreased liver damage, and inhibited APAP-induced prolonged hepatic JNK phosphorylation in WT mice. Gadd45β expression was increased after APAP treatment, and the expression of Gadd45β was further enhanced by metformin. The effects of metformin on APAP-induced liver injury and JNK phosphorylation were abolished in Gadd45β KO mice. Notably, subtoxic doses of APAP caused cell death and sustained JNK phosphorylation in Gadd45β-deficient primary hepatocytes. In parallel, APAP increased mortality, severe liver injury, and JNK activation in Gadd45β KO mice. Interestingly, metformin administered after APAP treatment protected against APAP-evoked hepatotoxicity in WT mice, but not in Gadd45β KO mice. Conclusions: This study is the first to demonstrate that metformin shows protective and therapeutic effects against APAP overdose-evoked hepatotoxicity via Gadd45β-dependent JNK regulation. Metformin would be a promising therapeutic strategy for treatment of APAP overdose.

工業敎育大學 敎育改善에 關한 硏究(Ⅱ)

孟琦錫,洪元杓,任洪彬,李廷玟,朴萬植,李載元,金八圭,權五憲,成世鎭,朴東徹,金太均,李定根 충남대학교 공업교육연구소 1981 論文集 Vol.4 No.1

Since the College of Industrial Education of Chungnam National University took charge of technical teacher preparation in 1977, much efforts have been concentrated on the activities for creating favorable educational environments in terms of curricula, pedagogic affairs, inner and outer facilities, etc. In this study some imposed barriers which are likely to hinder this college from achieving better education were identified and analysed. Considerably large scale of the student enrollment in comparison with the market demand is a prevailing issue which causes an adverse effect for clarification of the educational goal of the college and another problem is concerned with the student entry criteria which do not require the pre-experiences in the field. Under this circumstances, a guide line to improve the teacher education is recommended as follow; 1) The number of the student enrollment should be adjusted to meet the minimum range in the wave of the technical teacher demand projection and the shortage of teacher could be covered by the graduates from the shortterm courses in this college. 2) The current curriculum is accordingly recommended to be diversified taking into consideration the qualification of the student. The suggested consists of four-year regular course, one-year course, and six-month course and the short-term courses are provided to induce the experienced people from industries. 3) In order to have teachers adjust themselves to changing technology, education on sound and fundamental knowledges should be provided in the pre-service education course and education on advanced knowledges and applied theories deferred to the in-service training course. 4) In the four-year pre-service education, the general education and pedagogic subjects are to be drastically intensified from 18 credits and 22 credits up to 40 credits and 30 credits respectively.

Synthesis of anionic multichain type surfactant and its effect on methane gas hydrate formation

Kwon, Y.A.,Park, J.M.,Jeong, K.E.,Kim, C.U.,Kim, T.W.,Chae, H.J.,Jeong, S.Y.,Yim, J.H.,Park, Y.K.,Lee, J.d. Korean Society of Industrial and Engineering Chemi 2011 Journal of industrial and engineering chemistry Vol.17 No.1

This paper reports an experimental study on the effects of novel anionic multichain disulfonate surfactant on the formation of methane gas hydrate. A series of surfactants with sodium sulfonic acid groups and different hydrophobic carbon chain lengths (C<SUB>8</SUB>, C<SUB>10</SUB>, and C<SUB>12</SUB>) were synthesized, and the effects of carbon chain length and concentration on methane hydrate formation kinetics were systematically investigated. Methane hydrate formation was conducted in a magnetic stirred vessel at the constant temperature of 274.15K and in a pressure range of 3.5-4.0MPa. All surfactants showed kinetic promoting behavior for methane gas hydrate formation, and the surfactant with the shortest chain length showed the highest acceleration effect. In addition, this multichain disulfonate surfactant exhibited higher methane storage capacity than SDS (sodium dodecyl sulfate) even at lower surfactant concentration, due to its lower critical micelle concentration (CMC) and the surface tension itself of the Gemini-type multichain surfactant.