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Lee, Gisuk,Joo, Youngsung,Baldwin, Ian T.,Kim, Sang-Gyu The Ecological Society of Korea 2021 Journal of Ecology and Environment Vol.45 No.3
Background: Plants are able to optimize defense responses induced by various herbivores, which have different feeding strategies. Local and systemic responses within a plant after herbivory are essential to modulate herbivore-specific plant responses. For instance, leaf-chewing herbivores elicit jasmonic acid signaling, which result in the inductions of toxic chemicals in the attacked leaf (tissue-specific responses) and also in the other unattacked parts of the plant (systemic responses). Root herbivory induces toxic metabolites in the attacked root and alters the levels of transcripts and metabolites in the unattacked shoot. However, we have little knowledge of the local and systemic responses against stem-boring herbivores. In this study, we examined the systemic changes in metabolites in the wild tobacco Nicotiana attenuata, when the stem-boring herbivore Trichobaris mucorea attacks. Results: To investigate the systemic responses of T. mucorea attacks, we measured the levels of jasmonic acid (JA), JA-dependent secondary metabolites, soluble sugars, and free amino acids in 7 distinct tissues of N. attenuata: leaf lamina with epidermis (LLE), leaf midrib (LM), stem epidermis (SE), stem pith (SP), stem vascular bundle (SV), root cortex with epidermis (RCE), and root vascular bundle (RV). The levels of JA were increased in all root tissues and in LM by T. mucorea attacks. The levels of chlorogenic acids (CGAs) and nicotine were increased in all stem tissues by T. mucorea. However, CGA was systematically induced in LM, and nicotine was systematically induced in LM and RCE. We further tested the resource allocation by measuring soluble sugars and free amino acids in plant tissues. T. mucorea attacks increased the level of free amino acids in all tissues except in LLE. The levels of soluble sugars were significantly decreased in SE and SP, but increased in RV. Conclusions: The results reveal that plants have local- and systemic-specific responses in response to attack from a stem-boring herbivore. Interestingly, the level of induced secondary metabolites was not consistent with the systemic inductions of JA. Spatiotemporal resolution of plant defense responses against stem herbivory will be required to understand how a plant copes with attack from herbivores from different feeding guilds.
FARO tests corium-melt cooling in water pool: Roles of melt superheat and sintering in sediment
Hwang, Gisuk,Kaviany, Massoud,Moriyama, Kiyofumi,Park, Hyun Sun,Hwang, Byoungcheol,Lee, Mooneon,Kim, Eunho,Park, Jin Ho,Nasersharifi, Yahya Elsevier 2016 Nuclear engineering and design Vol.305 No.-
<P><B>Abstract</B></P> <P>The FARO tests have aimed at understanding an important severe accident mitigation action in a light water reactor when the accident progresses from the reactor pressure vessel boundary. These tests have aimed to measure the coolability of a molten core material (corium) gravity dispersed as jet into a water pool, quantifying the loose particle diameter distribution and fraction converted to cake under range of initial melt superheat and pool temperature and depth. Under complete hydrodynamic breakup of corium and consequent sedimentation in the pool, the initially superheated corium can result in debris bed consisting of discrete solid particles (loose debris) and/or a solid cake at the bottom of the pool. The success of the debris bed coolability requires cooling of the cake, and this is controlled by the large internal resistance. We postulate that the corium cake forms when there is a remelting part in the sediment. We show that even though a solid shell forms around the melt particles transiting in the water pool due to film-boiling heat transfer, the superheated melt allows remelting of the large particles in the sediment (depending on the water temperature and the transit time) using the COOLAP (Coolability Analysis with Parametric fuel-cooant interaction models) code. With this remelting and its liquid-phase sintering of the non-remelted particles, we predict the fraction of the melt particles converting to a cake through liquid sintering. Our predictions are in good agreement with the existing results of the FARO experiments. We address only those experiments with pool depths sufficient/exceeding the length required for complete breakup of the molten jet. Our analysis of the fate of molten corium aimed at devising the effective scenarios for its safe cooling in the containment so that predicted the minimum pool depth for no cake formation as functions of the melt superheat and water (subcooled/saturation) temperatures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The numerical approach for FARO experimental data is suggested. </LI> <LI> The cooling mechanism of ex-vessel corium is suggested. </LI> <LI> The predicted minimum pool depth for no cake formation is suggested. </LI> </UL> </P>
이민성(Lee Minsung),정연일(Chung Younil),정기석(Chung Gisuk),한성수 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
In this study, light weight wheel rim, one of the automotive chassis part, was developed using TWIP(Twinning Induced Plasticity) steel. TWIP steel has advantage to achieve complex cross section due to the excellent formability. An optimal design of wheel rim was suggested from the parametric study of design variables : distance of mounting groove, bead radius, position and the number of beads. The beads were added in the circumference direction of a rim surface to enhance the stiffness. The structure and durability analysis were performed with FEA in order to verify its performance. Adding beads around a wheel rim could be a dominant factor to reduce maximum stress and improve fatigue life under radial load. The hydroforming process for manufacturing a wheel rim with enhanced stiffness and reduced weight is proposed.
Rhodamine spirolactam sensors operated by sulfur-cooperated metal complexation
Heo, Gisuk,Lee, Dahye,Kim, Chi Gwan,Do, Jung Yun Elsevier 2018 Spectrochimica acta. Part A, Molecular and biomole Vol.188 No.-
<P><B>Abstract</B></P> <P>New rhodamine Schiff base sensors were developed to improve selective sensing by introducing sulfide, ester, and dithiocarbonate groups, as well as using ketones coupled to rhodamine-hydrazine. Metal sensing proceeded through the 1:1 complexation of the metal ion for most sensors in the presence of Cu<SUP>2+</SUP> and Hg<SUP>2+</SUP>. A sensor carrying a dithiocarbonate group responded selectively to Hg<SUP>2+</SUP> showing a strong colorimetric change and intense fluorescence. The association constants of the sensors were determined from a linear plot performed at micro-molar concentrations to afford values in the range of 10<SUP>4</SUP>. Sensing was interrupted at the initial time of Hg<SUP>2+</SUP> exposure due to the isomerization of imine and preferential metal bonding of two dithiocarbonate groups regardless of the main structure of rhodamine. The sensors exhibited the reversible and reproducible performance for Hg<SUP>2+</SUP> sensing.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dithiocarbonate group contributes to Hg sensing of new rhodamine sensor. </LI> <LI> Cooperative metal binding of proximal groups are discussed. </LI> <LI> Sensing properties are compared by association constants. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Sang-Gyu Kim,Gisuk Lee,Youngsung Joo,Ian T. Baldwin 한국응용곤충학회 2018 한국응용곤충학회 학술대회논문집 Vol.2018 No.04
Herbivorous insects use plant metabolites to inform their host plant selection for oviposition. These host-selection behaviors are often consistent with the preference-performance hypothesis; females oviposit on hosts that maximize the performance of their offspring. However, the metabolites used for these oviposition choices and those responsible for differences in offspring performance remain unknown for ecologically-relevant interactions. In this time, I will talk about the host-selection behaviors of two sympatric weevils, the Datura (Trichobaris compacta) and tobacco (T. mucorea) weevils in field- and glasshouse-experiments with transgenic host plants specifically altered indifferent components of their secondary metabolism. In addition, I will show that adult females are able to choose the best host plant for their offspring and use chemicals different from those that influence larval performance to inform their oviposition decisions.