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Interference Effect betweenϕandΛ(1520)Production Channels in theγp→K+K−pReaction near Threshold
Ryu, S. Y.,Ahn, J. K.,Nakano, T.,Ahn, D. S.,Ajimura, S.,Akimune, H.,Asano, Y.,Chang, W. C.,Chen, J. Y.,Daté,, S.,Ejiri, H.,Fujimura, H.,Fujiwara, M.,Fukui, S.,Hasegawa, S.,Hicks, K.,Horie, K.,Ho American Physical Society 2016 Physical Review Letters Vol.116 No.23
<P>The phi-Lambda(1520) interference effect in the gamma p -> K(+)K(-)p reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between phi and Lambda(1520) production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when K+K- pairs are observed at forward angles but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the root s = 2.1 GeV bump structure in forward differential cross sections for phi photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange, or rescattering processes via other hyperon states.</P>
Lee, J,Hwang, Y J,Boo, J H,Han, D,Kwon, O K,Todorova, K,Kowall, N W,Kim, Y,Ryu, H Macmillan Publishers Limited 2011 Cell death and differentiation Vol.18 No.11
Huntington's disease (HD) is an autosomal-dominant neurological disorder caused by expanded CAG repeats in the Huntingtin (Htt) gene, but it is not known how this mutation causes neurodegeneration. Herein, we found that dysfunction of upstream binding factor-1 (UBF-1) is linked to reduced ribosomal DNA (rDNA) transcription in HD. We identified that UBF1 acetylation at Lys (K) 352 by CREB binding protein (CBP) is crucial for the transcriptional activity of rDNA. UBF1 mutation (K352A, K352Q, and K352R) decreased rDNA transcriptional activity. Moreover, both CBP–dHAT mutant and knockdown of CBP by siRNA reduced acetylation of UBF1 and resulted in the decreased transcription of rDNA into rRNA. ChIP analysis showed a significant reduction of UBF1 occupancy in the promoter of rDNA in STHdh<SUP>Q111</SUP> cell line model of HD. These results demonstrate that abnormal activity of UBF1 and its acetylation by CBP are linked to impaired rDNA transcription in HD. This novel mechanism suggests that modulation of UBF-mediated rDNA synthesis by CBP may be a therapeutic target for improving neuronal rDNA transcription in HD.
Byun, C.K.,Kwon, S.J.,Im, H.B.,Ahn, H.S.,Ryu, H.J.,Yi, K.B. Pergamon Press 2016 RENEWABLE ENERGY Vol.87 No.1
CO<SUB>2</SUB> sorption reactions at 20 bar and two different temperatures (i.e., 180 and 220 <SUP>o</SUP>C) using a K-Mg-based CO<SUB>2</SUB> sorbent were carried out in a custom-designed high-pressure thermogravimetric analyzer (pressurized bubbling fluidized bed reactor on a scale) coupled with a gas chromatograph. The experimental apparatus, including the thermogravimetric analyzer, was custom-designed to measure weight changes caused by either CO<SUB>2</SUB> sorption or water sorption or both. Analysis of the CO<SUB>2</SUB> sorption reaction revealed that water sorption takes place rapidly with a moderate CO<SUB>2</SUB> sorption rate at the early stage of the reaction. Then, the reaction migrates to CO<SUB>2</SUB> sorption with simultaneous water desorption. Therefore, the mechanism of the CO<SUB>2</SUB> sorption reaction is assumed to consist of fast hydration of K<SUB>2</SUB>CO<SUB>3</SUB> and MgO, formation and decomposition of KHCO<SUB>3</SUB>, and finally carbonation of Mg(OH)<SUB>2</SUB> resulting in MgCO<SUB>3</SUB> as the main product. K<SUB>2</SUB>CO<SUB>3</SUB> is assumed to provide an efficient pathway for CO<SUB>2</SUB> and water to travel into the core region of the sorbent via a reversible reaction between K<SUB>2</SUB>CO<SUB>3</SUB> and KHCO<SUB>3</SUB>.
Shin, M.S.,Han, S.K.,Ryu, J.S.,Kim, K.S.,Lee, W.K. Blackwell Publishing Ltd 2008 Journal of Applied Microbiology Vol.105 No.2
<P>Abstract</P><P>Aims: </P><P>Screening and partial characterization of a bacteriocin produced by <I>Pediococcus pentosaceus</I> K23-2 isolated from Kimchi, a traditional Korean fermented vegetable.</P><P>Methods and Results: </P><P>A total of 1000 lactic acid bacteria were isolated from various Kimchi samples and screened for the production of bacteriocin. Pediocin K23-2, a bacteriocin produced by the <I>Pediococcus pentosaceus</I> K23-2 strain, showed strong inhibitory activity against <I>Listeria monocytogenes</I>. The bacteriocin activity remained unchanged after 15 min of heat treatment at 121°C or exposure to organic solvents; however, it diminished after treatment with proteolytic enzymes. The bacteriocin was maximally produced at 37°C, when the pH of the culture broth was maintained at 5·0 during the fermentation, although the optimum pH for growth was 7·0. The molecular weight of the bacteriocin was about 5 kDa according to a tricine SDS-PAGE analysis.</P><P>Conclusions: </P><P><I>Pediococcus pentosaceus</I> K23-2 isolated from Kimchi produces a bacteriocin, which shares similar characteristics to the Class IIa bacteriocins. The bacteriocin is heat stable and shows wide antimicrobial activity against Gram-positive bacteria, especially <I>L. monocytogenes</I>.</P><P>Significance and Impact of the Study: </P><P>Pediocin K23-2 and pediocin K23-2-producing <I>P. pentosaceus</I> K23-2 could potentially be used in the food and feed industries as natural biopreservatives, and for probiotic application to humans or livestock.</P>
Soft Magnetic Properties of Annealed Co - Based Amorphous Co66Fe₄Ni₁B15Si₁₄ Alloy Ribbon
J. S. Yang,D. Son,Y. Cho,K. S. Ryu 한국자기학회 1997 Journal of Magnetics Vol.2 No.4
The amorphous Co-based alloy Co_(66)Fe₄Ni₁B_(15)Si₁₄ (Metglas^® 2714A) is a suitable magnetic core material for high frequency operation. Appreciable reduction of the coercive force can be achieved by proper heat treatment. In this study, samples annealed at wide temperature range were analyzed using differential scanning calorimetry, high frequency B-H loop tester, X-ray diffractometer and resistivity meter. The results show that coercive force at 10 ㎑ decreases with increasing annealing temperature up to 773 K, but dramatically increases above this temperature. The squareness shows that the magnetic anisotropy on longitudinal direction of the as-cast state remains up to 773 K. Above this temperature, it decreases down to 0.5 that represents random distribution of magnetic domains. The crystallization abruptly occurs between 781 K and 783 K.
High-Performance Blue InGaN Laser Diodes With Single-Quantum-Well Active Layers
Ryu, H.Y.,Haleem, K.H.,Lee, S.N.,Jang, T.,Son, J.K.,Paek, H.S.,Sung, Y.J.,Kim, H.K.,Kim, K.S.,O.H. Nam,Park, Y.J.,Shim, J.I. IEEE 2007 Photonics Technology Letters Vol.19 No.21
<P>The authors report on the high-performance blue laser diodes (LDs) with an emission wavelength of ~448 nm employing InGaN single-quantum-well (QW) active layers. At 100-mW continuous-wave (CW) output power, operation current and voltage are, respectively, 150 mA and 5.3 V, corresponding to the wall plug efficiency of >12%, a record value for the single-mode InGaN LDs with blue wavelengths. The single QW blue LD showed normal temperature dependence of light output-current curves with the characteristic temperature of 170 K. In addition, we demonstrate a high level of catastrophic optical damage of >300 mW and long device lifetime under CW operation condition at room temperature.</P>
Ryu, K.,Hwang, S.Y.,Kim, K.H.,Kang, J.H.,Lee, E.K. Elsevier Science Publishers 2008 Journal of biotechnology Vol.133 No.1
One of the major problems of wild-type lignin peroxidase (LiP) is its inactivity at the presence of excess H<SUB>2</SUB>O<SUB>2</SUB> and high concentration of aromatic compounds. Little is known about the substrate-binding site of LiP, and functionality improvement of LiP was not actively tried by genetic engineering and directed evolution. In order to improve LiPs functionality, we performed directed evolution with a colorimetric screening method. Finally, three types of LiP mutants were screened. The catalytic efficiency of the variants toward 2,4-dichlorophenol (DCP) degradation activity and the stability against H<SUB>2</SUB>O<SUB>2</SUB> was increased over the wild type. The K<SUB>m</SUB> value of the variants toward H<SUB>2</SUB>O<SUB>2</SUB> was increased, but K<SUB>m</SUB> value toward 2,4-DCP degradation was reduced. Overall, The K<SUB>cat</SUB>/K<SUB>m</SUB> values of the mutants toward 2,4-DCP was increased ca. 4-fold, and that toward H<SUB>2</SUB>O<SUB>2</SUB> was increased ca. 89-fold. Amino acid sequence analysis indicated that the most of the mutations were located on the enzyme surface. We expect that these results coupled with recombining mutation can be successfully applied to the molecular evolution cycles for screening of LiPs and other oxidative enzymes with improved functionality and stability.
OGLE-2016-BLG-1190Lb: The First<i>Spitzer</i>Bulge Planet Lies Near the Planet/Brown-dwarf Boundary
Ryu, Y.-H.,Yee, J. C.,Udalski, A.,Bond, I. A.,Shvartzvald, Y.,Zang, W.,Jaimes, R. Figuera,Jørgensen, U. G.,Zhu, W.,Huang, C. X.,Jung, Y. K.,Albrow, M. D.,Chung, S.-J.,Gould, A.,Han, C.,Hwang, K.-H.,Sh American Astronomical Society 2018 The Astronomical journal Vol.155 No.1
<P>We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the Galactic bulge/ bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object. The planet's mass, M-p = 13.4 +/- 0.9 M-J, places it right at the deuteriumburning limit, i. e., the conventional boundary between 'planets' and 'brown dwarfs.' Its existence raises the question of whether such objects are really ' planets' (formed within the disks of their hosts) or 'failed stars' (lowmass objects formed by gas fragmentation). This question may ultimately be addressed by comparing disk and bulge/bar planets, which is a goal of the Spitzer microlens program. The host is a G dwarf, M-host = 0.89. +/- 0.07 M-circle dot, and the planet has a semimajor axis a similar to 2.0 au. We use Kepler K2 Campaign 9 microlensing data to break the lens-mass degeneracy that generically impacts parallax solutions from Earth-Spitzer observations alone, which is the first successful application of this approach. The microlensing data, derived primarily from near-continuous, ultradense survey observations from OGLE, MOA, and three KMTNet telescopes, contain more orbital information than for any previous microlensing planet, but not quite enough to accurately specify the full orbit. However, these data do permit the first rigorous test of microlensing orbital-motion measurements, which are typically derived from data taken over < 1% of an orbital period.</P>
OGLE-2016-BLG-0693LB: Probing the Brown Dwarf Desert with Microlensing
Ryu, Y.-H.,Udalski, A.,Yee, J. C.,Albrow, M. D.,Chung, S.-J.,Gould, A.,Han, C.,Hwang, K.-H.,Jung, Y. K.,Shin, I.-G.,Zhu, W.,Cha, S.-M.,Kim, D.-J.,Kim, H.-W.,Kim, S.-L.,Lee, C.-U.,Lee, Y.,Park, B.-G.,P American Astronomical Society 2017 The Astronomical journal Vol.154 No.6
<P>We present an analysis of microlensing event OGLE-2016-BLG-0693, based on the survey-only microlensing observations by the OGLE and KMTNet groups. In order to analyze the light curve, we consider the effects of parallax, orbital motion, and baseline slope, and also refine the result using a Galactic model prior. From the microlensing analysis, we find that the event is a binary composed of a low-mass brown dwarf (49(-18)(+20) Mj) companion and a K- or G-dwarf host, which lies at a distance of 5.0 +/- 0.6 kpc toward the Galactic bulge. The projected separation between the brown dwarf and its host star is less than similar to 5 au, thus it is likely that the brown dwarf companion is located in the brown dwarf desert.</P>
Alcohol+iso-Octane 혼합계의 등온 기액평형과 공비점
류선아,오종혁,나재익,백승관,한규진,박소진 忠南大學校 産業技術硏究所 1997 산업기술연구논문집 Vol.12 No.1
Isothermal vapor-liquid equilibria(VLE) for binary systems of C₂∼C₄ alcohol+iso-octane were measured by headspace gas chromatography(HSGC) at 60℃. All the binary mixtures showed the positive deviation from the Raoult's law and homogeneous minimum azeotropes. VLE data were correlated by common ge models and compared with calculated values by modified UNFAC group contribution method. Their mean deviations of vapor phase composition were less than 1%. Precise azeotropic concentrations were also measured directly by spining band distillator for each binary systems.