한국천문연구원 Hα 태양전면관측시스템의 바닥고르기 연구

박형민,김연한,봉수찬,박영득,조경석,장비호,최성환,나자경,이승민,채종철,Park, H.M.,Kim, Y.H.,Bong, S.C.,Park, Y.D.,Cho, K.S.,Jang, B.H.,Choi, S.,Nah, J.,Lee, S.M.,Chae, J. 한국천문학회 2008 天文學論叢 Vol.23 No.2

We have performed the flat-fielding correction for the $H{\alpha}$ full-disk monitoring system of KASI (Korea Astronomy and Space Science Institute), which is installed in the Solar Flare Telescope (SOFT) at the top of Bohyun Mountain. For this, we used a new method developed by Chae (2004), to determine the flat pattern from a set of relatively shifted images. Using this method, we successfully obtained the flat pattern for $H{\alpha}$ full-disk observations and compared our result with the image observed in Catania Astrophysical Observatory. The method that we used in this study seems to be quite powerful to obtain the flat image for solar observations. In near future, we will apply this method for the flat-fielding correction of all solar imaging instruments in KASI.

Key properties of Ni-MgO-CeO2, Ni-MgO-ZrO2, and Ni-MgO-Ce(1-x)Zr(x)O2 catalysts for the reforming of methane with carbon dioxide

Jang, W. J.,Kim, H. M.,Shim, J. O.,Yoo, S. Y.,Jeon, K. W.,Na, H. S.,Lee, Y. L.,Jeong, D. W.,Bae, J.,Nah, I. Royal Society of Chemistry 2018 GREEN CHEMISTRY Vol.20 No.7

<P>CeO2, ZrO2, and CeO2-ZrO2 supported on MgO-promoted Ni catalysts are developed and applied to the reforming of methane with carbon dioxide. The catalysts are prepared by the one-step co-precipitation/aging method and characterized through various techniques such as X-ray diffraction, Brunauer-Emmet-Teller measurements, pore distribution, X-ray photoelectron spectroscopy, X-ray absorption near edge spectroscopy, extended X-ray absorption fine structure analysis, H-2-temperature programmed reduction, H-2-chemisorption, Raman analysis, thermogravimetry analysis, and pulse H-2-CO2 reactions. Ni-MgO-CeO2 shows the smallest Ni particle size and the particle size decreases with increasing ZrO2 content. Ni-MgO-Ce0.6Zr0.4O2 exhibits the largest oxygen storage capacity among the prepared catalysts. The size of the Ni particles and the oxygen storage capacity are found to be the primary and secondary key factors that influence the catalytic performance, respectively. The turnover frequency is dependent on the size of the Ni particles, but the catalytic performance is affected by the number of Ni active sites, which is estimated from the reduction degree and Ni particle size. Overall, the Ni-MgO-Ce0.8Zr0.2O2 catalyst shows the best performance owing to the high reduction degree and small Ni particle size.</P>

Quantifying herbicide dose-response and resistance in <i>Echinochloa</i> spp. by measuring root length in growth pouches

Zhang, C. J.,Lim, S. H.,Kim, J. W.,Song, J. S.,Yook, M. J.,Nah, G.,Valverde, B. E.,Kim, D. S. Canadian Science Publishing 2015 Canadian journal of plant science. Revue canadienn Vol.95 No.6

<P> Zhang, C. J., Lim, S. H., Kim, J. W., Song, J. S., Yook, M. J., Nah, G., Valverde, N. E. and Kim, D. S. 2015. Quantifying herbicide dose-response and resistance in Echinochloa spp. by measuring root length in growth pouches. Can. J. Plant Sci. 95: 1181-1192. The aim of the presented study was to develop a bioassay for rapid diagnosis of herbicide dose-response and resistance in Echinochloa. Pre-germinated seeds of Echinochloa spp. were incubated in growth pouches (18 cm×16.5 cm) containing herbicide solutions in a range of concentrations. Shoot and root lengths were measured after 6 d of incubation. Dose-responses estimated by measuring root lengths in the growth pouches were well-described by the log-logistic dose-response model and similar to those estimated by a whole-plant assay. Accurate dose-response curves were successfully generated for several herbicides with different modes of action, suggesting that the growth pouch method can be used for herbicide bioassays. The suitability of the growth pouch method for rapid diagnosis of acetyl coenzyme-A carboxylase (ACCase) and acetolactate synthase (ALS) inhibitor resistance in Echinochloa spp. was also tested. For cyhalofop-butyl, resistant and susceptible biotypes were discriminated at 180-300 mg a.i. L<SUP>−1</SUP> and 80-120 mg a.i. L<SUP>−1</SUP> for barnyardgrass (E. crus-galli) and late watergrass (E. oryzicola), respectively. For penoxsulam, the discriminatory dosage was 350-500 mg a.i. L<SUP>−1</SUP> for barnyardgrass and 650-1000 mg a.i. L<SUP>−1</SUP> for late watergrass. The method was further used to identify late watergrass biotypes resistant and susceptible to two other ALS inhibitors, azimsulfuron and bispyribac-sodium. Our results show that the growth pouch method can be reliably used in herbicide dose-response studies and to diagnose herbicide resistance in Echinochloa spp., with significant time and cost savings compared with conventional whole-plant assays. </P>

Polymeric micellar nanoplatforms for Fenton reaction as a new class of antibacterial agents

Park, S.C.,Kim, N.H.,Yang, W.,Nah, J.W.,Jang, M.K.,Lee, D. Elsevier Science Publishers 2016 Journal of controlled release Vol.221 No.-

<P>Reactive oxygen species (ROS) produced by host phagocytes exert antibacterial action against a variety of pathogens and ROS-induced oxidative stress is the governing mechanism for the antibacterial activity of major bactericidal antibiotics. In particular, hydroxyl radical is a strong and nonselective oxidant which can damage biomolecules such as DNA, proteins and lipids. Ferrous ion is known to convert mild oxidant hydrogen peroxide (H2O2) into highly reactive and toxic hydroxyl radicals, referred to as Fenton reaction. Herein, we report a new class of antibacterial agents based on Fenton reaction-performing nanostructures, composed of H2O2 generating polymer (PCAE) and iron-containing ferrocene. Amphiphilic PCAE was designed to incorporate H2O2-generating cinnamaldehyde through acid-cleavable linkages and self-assemble to formthermodynamically stable micelles which could encapsulate ferrocene in their hydrophobic core. All the experiments in vitro display that ferrocene-loaded PCAE micelles produce hydroxyl radicals to kill Escherichia coli and Pseudomonas aeruginosa through membrane damages. Intraperitoneally injected ferrocene-loaded PCAE micelles significantly reduced the lung damages and therefore increased the survival rate of mice infected with drug resistant P. aeruginosa. Given their potent antibacterial activity, ferrocene-loaded PCAE micelles hold great potential as a new class of ROS-manipulating antibacterial agents. (C) 2015 Elsevier B.V. All rights reserved.</P>

트랙터 견인형 TMR 배합기의 개발(Ⅲ) : 경제성 분석 Cost analysis

박경규,김혁주,서상훈,장철,이종순,나규동,홍동혁,하유신 한국농업기계학회 2000 바이오시스템공학 Vol.25 No.4

Estimation of spectroscopic constants of isotopologues: Dependence of the scaling factors on isotopic mass

Kim, M.,Shin, B.k.,Nah, M.K.,Kim, Y.,Lee, K.H.,Park, H.,Lee, C.,Lee, J.,Choi, T.H.,Jeong, D.Y. Elsevier Scientific Pub. Co 2015 Computational & theoretical chemistry Vol.1054 No.-

Scaling factors have been applied to the estimation of the spectroscopic constants of pure isotopologues of two polyatomic molecules: ammonia (NH<SUB>3</SUB>) and formaldehyde (HCHO). Vibrational frequencies and rotational constants of four isotopologues of each molecule have been calculated using the resolution-of-the-identity second-order coupled cluster (RICC2) and coupled cluster singles and doubles (CCSD) methods with the aug-cc-pVDZ and aug-cc-pVTZ basis sets. It has been observed that the scaling factors for the vibrational frequencies and rotational constants of the isotopologues are dependent on the isotopic mass. With the given scaling factors calculated at the CCSD/aug-cc-pVTZ level of theory, the experimental spectroscopic data are reproduced with an error range of 0.6% for the D<SUP>13</SUP>CD<SUP>16</SUP>O isotopologue. In addition, the spectrum of H<SUP>13</SUP>CH<SUP>16</SUP>O is accurately predicted with the scaling factors calculated from the other isotopologues. The estimated spectrum is in good agreement with the experimental spectrum.

The Influence of Plasma Surface Modification on Frictional Property of Natural Rubber Vulcanizates

( D. H. Kim ),( G. Mathew ),( D. J. Jeon ),( B. Jurkowskl ),( B. Jurkowska ),( C. Nah ) 한국고무학회 2004 엘라스토머 및 콤포지트 Vol.39 No.1

라디오 주파수(13.56 MHz) 무전극 종형 플라즈마 반응기를 이용하여 천연고무 가교체의 표면을 클로로디플루오로메탄으로 처리하였다. FT-적외선 분광분석으로 표면개질 정도를 정성적으로 조사하였다. 플라즈마 처리표면의 마찰힘은 플라즈마 처리시간 증가에 따라 감소하였다. 고무표면에 에틸렌글리콜과 물을 떨어뜨려 접촉각을 측정한 결과 플라즈마 처리에 따라 감소하는 것으로 미루어 플라즈마 개질에 따라 표면극성이 증가하는 것을 확인하였다. 유리판 표면을 동일조건으로 플라즈마 처리한 경우는 극성의 감소만이 확인되었다. 표면자유에너지의 London 비극성 및 극성요소를 계산하는데 있어서 기하평균법과 조화평균법이 유용한 것으로 확인되었다. 평균방법에 관계없이 플라즈마 처리시간이 증가함에 따라 표면자유에너지는 증가하였다. 그러나 조화평균법으로 계산된 자유에너지가 기하평균법으로 계산된 값에 비해 상대적으로 높았다. 플라즈마 표면개질은 마찰의 계면, 히스테리시스, 점성요소들에 영향을 미침으로써 마찰계수를 변화시키는 것으로 나타났다. The plasma surface modification of natural rubber vulcanizate was carried out using chlorodifluoromethane in a radio-frequency (13.56 ㎒) electrodeless bell type plasma reactor. The modification was qualitatively assessed by Fourier transform infrared spectroscopy. The frictional force of the plasma-treated surface was found to decrease with the time of plasma treatment. An increase in the surface polarity, as evidenced by the decrease in contact angle of a sessile drop of water drop of water and ethylene glycol on the natural rubber vulcanizate surface, was noted with the plasma modification. In the case of similar plasma treatment of glass surface, only a reduction in the polarity was observed. The use of geometric and harmonic mean methods was found to be useful to evaluate the London dispersive and specific components of surface free energy. Irrespective of the method used for evaluation, an increasing trend in the surface free energy was noted with increasing plasma treatment time. However, the harmonic mean method yielded comparatively higher values of surface free energy than the geometric mean method. The plasma surface modification was found to vary the frictional coefficient by influencing the interfacial, hysteresis and viscous components of friction in opposing dual manners.

The role of system Xc^- in methamphetamine-induced dopaminergic neurotoxicity in mice

Dang, D.K.,Shin, E.J.,Tran, H.Q.,Kim, D.J.,Jeong, J.H.,Jang, C.G.,Nah, S.Y.,Sato, H.,Nabeshima, T.,Yoneda, Y.,Kim, H.C. Pergamon Press 2017 Neurochemistry International Vol.108 No.-

The cystine/glutamate antiporter (system Xc<SUP>-</SUP>, Sxc) transports cystine into cell in exchange for glutamate. Since xCT is a specific subunit of Sxc, we employed xCT knockout mice and investigated whether this antiporter affected methamphetamine (MA)-induced dopaminergic neurotoxicity. MA treatment significantly increased striatal oxidative burdens in wild type mice. xCT inhibitor [i.e., S-4-carboxy-phenylglycine (CPG), sulfasalazine] or an xCT knockout significantly protected against these oxidative burdens. MA-induced increases in Iba-1 expression and Iba-1-labeled microglial immunoreactivity (Iba-1-IR) were significantly attenuated by CPG or sulfasalazine administration or xCT knockout. CPG or sulfasalazine significantly attenuated MA-induced TUNEL-positive cell populations in the striatum of Taconic ICR mice. The decrease in excitatory amino acid transporter-2 (or glutamate transporter-1) expression and increase in glutamate release were attenuated by CPG, sulfasalazine or xCT knockout. In addition, CPG, sulfasalazine or xCT knockout significantly protected against dopaminergic loss (i.e., decreases in tyrosine hydroxylase expression and immunoreactivity, and an increase in dopamine turnover rate) induced by MA. However, CPG, sulfasalazine or xCT knockout did not significantly affect the impaired glutathione system [i.e., decrease in reduced glutathione (GSH) and increase in oxidized glutathione (GSSG)] induced by MA. Our results suggest that Sxc mediates MA-induced neurotoxicity via facilitating oxidative stress, microgliosis, proapoptosis, and glutamate-related toxicity.

Identification of glucose-6-phosphate transporter as a key regulator functioning at the autophagy initiation step

Ahn, H.H.,Oh, Y.,Lee, H.,Lee, W.,Chang, J.W.,Pyo, H.K.,Nah, D.h.,Jung, Y.K. North-Holland Pub ; Elsevier Science Ltd 2015 FEBS letters Vol.589 No.16

Autophagy is a catabolic process involving autophagosome formation via lysosome. However, the initiation step of autophagy is largely unknown. We found an interaction between ULK1 and ATG9 in mammalian cells and utilized the interaction to identify novel regulators of autophagy upstream of ULK1. We established a cell-based screening assay employing bimolecular fluorescence complementation. By performing gain-of-function screening, we identified G6PT as an autophagy activator. G6PT enhanced the interaction between N-terminal Venus-tagged ULK1 and C-terminal Venus-tagged ATG9, and increased autophagic flux independent of its transport activity. G6PT negatively regulated mTORC1 activity, demonstrating that G6PT functions upstream of mTORC1 in stimulating autophagy.

Gintonin attenuates depressive-like behaviors associated with alcohol withdrawal in mice

Kim, H.J.,Park, S.D.,Lee, R.M.,Lee, B.H.,Choi, S.H.,Hwang, S.H.,Rhim, H.,Kim, H.C.,Nah, S.Y. Elsevier/North-Holland Biomedical Press 2017 Journal of affective disorders Vol.215 No.-

Background: Panax ginseng Meyer extracts have been used to improve mood and alleviate symptoms of depression. However, little is known about the extracts' active ingredients and the molecular mechanisms underlying their reported anti-depressive effects. Methods: Gintonin is an exogenous lysophosphatidic acid (LPA) receptor ligand isolated from P. ginseng. BON cells, an enterochromaffin cell line, and C57BL/6 mice were used to investigate whether gintonin stimulates serotonin release. Furthermore, the effects of gintonin on depressive-like behaviors following alcohol withdrawal were evaluated using the forced swim and tail suspension tests. Results: Treatment of BON cells with gintonin induced a transient increase in the intracellular calcium concentration and serotonin release in a concentration- and time-dependent manner via the LPA receptor signaling pathway. Oral administration of the gintonin-enriched fraction (GEF) induced an increase in the plasma serotonin concentration in the mice. Oral administration of the GEF in mice with alcohol withdrawal decreased the immobility time in two depression-like behavioral tests and restored the alcohol withdrawal-induced serotonin decrease in plasma levels. Limitations: We cannot exclude the possibility that the gintonin-mediated regulation of adrenal catecholamine release in the peripheral system, and acetylcholine and glutamate release in the central nervous system, could also contribute to the alleviation of depressive-like behaviors. Conclusion: The GEF-mediated attenuation of depressive-like behavior induced by alcohol withdrawal may be mediated by serotonin release from intestinal enterochromaffin cells. Therefore, the GEF might be responsible for the ginseng extract-induced alleviation of depression-related symptoms.