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Hyunkyu Sang,Jeong‑Il Kim 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.1
Plant pathogenic fungi and oomycetes cause severe losses of crop yield worldwide. Fungicides are widely applied to manage plant diseases caused by pathogenic fungi, but fungicide-resistant fungal populations have been increasingly reported. Recent techniques using RNA interference (RNAi), which define the ability of double-stranded RNA (dsRNA) to inhibit the expression of homologous gene(s), have been suggested for crop protection in an environmental-friendly way. These techniques, so-called host-induced gene silencing (HIGS) and spray-induced gene silencing (SIGS), are the innovative strategies to control plant diseases. The HIGS involves host expression of dsRNA targeting genes in interacting plant pathogens and the SIGS involves inhibition of plant pathogens through a direct spray of dsRNA targeting pathogen genes on plant tissues. In this review, we present recent studies of the HIGS and SIGS to protect plant diseases caused by fungal and oomycete pathogens.
Plant disease management using SDHI fungicides and mechanisms of SDHI resistance
Hyunkyu Sang(상현규),Haifeng Liu,Gahee Lee 한국농약과학회 2021 한국농약과학회 학술발표대회 논문집 Vol.2021 No.11
The succinate dehydrogenase inhibitor (SDHI) is a fungicide class containing 12 chemical groups and 24 different compounds and is widely applied to manage plant diseases caused by plant pathogenic fungi. SDHI fungicides inhibit fungal respiration by blocking the ubiquinone-binding site of the mitochondrial succinate dehydrogenase complex composed of four subunits, SdhA, SdhB, SdhC, and SdhD. Currently, SDHI fungicides have been treated to many different crops, fruits, turf, and vegetables and provide effective control of plant diseases. For example, one of the SDHI fungicides, fluopyram, has been used as a seed or foliar treatment for plant disease control and the soybean seed treatment of fluopyram effectively managed soybean sudden death syndrome caused by Fusarium virgulifrome. In addition, this fungicide displayed a good efficacy against the SDHI fungicide boscalid resistant Botrytis cinerea isolates, causing gray mold of grapes. Despite the effective disease control by SDHI fungicides, resistance to SDHI fungicides has been reported in many phytopathogenic fungal species such as Alternaria solani, Botrytis cinerea, Clarireedia homoeocarpa, and Zymoseptoria tritici. Most fungal strains resistant to SDHI fungicides contain mutation(s) in SdhB, SdhC, or SdhD gene and some fungal pathogens exhibited reduced sensitivity to SDHI fungicides harbor overexpression of ATP-binding cassette (ABC) or Major facilitator superfamily (MFS) transporters. In this presentation, the current status of plant disease management by SDHI fungicide applications and molecular mechanisms of SDHI resistance will be discussed.
Gravitational Wave Astrophysics with the Superconducting Low-frequency Gravitational-wave Telescope
Sang-Hyeon Ahn,Yeong-Bok Bae,Gungwon Kang,Chunglee Kim,Whansun Kim,John J. Oh,Sang Hoon Oh,Chan Park,Edwin J. Son,Hyung Mok Lee,Hyungwon Lee,Hyunkyu Lee,Chang-Hwan Lee,Ho Jung Paik 한국천문학회 2017 天文學會報 Vol.42 No.2
Molecular Mechanisms of Succinate Dehydrogenase Inhibitor Resistance in Phytopathogenic Fungi
Hyunkyu Sang,Hyang Burm Lee 한국식물병리학회 2020 식물병연구 Vol.26 No.1
The succinate dehydrogenase inhibitor (SDHI) is a class of fungicides, which is widely and rapidly used to manage fungal pathogens in the agriculture field. Currently, fungicide resistance to SDHIs has been devel- oped in many different plant pathogenic fungi, causing diseases on crops, fruits, vegetables, and turf. Under- standing the molecular mechanisms of fungicide resistance is important for effective prevention and resis- tance management strategies. Two different mechanisms have currently been known in SDHI resistance. The SDHI target genes, SdhB, SdhC, and SdhD, mutation(s) confer resistance to SDHIs. In addition, overexpression of ABC transporters is involved in reduced sensitivity to SDHI fungicides. In this review, the current status of SDHI resistance mechanisms in phytopathogenic fungi is discussed.
Association Between Sleep Quality and Anxiety in Korean Adolescents
Kim, Hyunkyu,Kim, Seung Hoon,Jang, Sung-In,Park, Eun-Cheol The Korean Society for Preventive Medicine 2022 예방의학회지 Vol.55 No.2
Objectives: Anxiety disorder is among the most prevalent mental illnesses among adolescents. Early detection and proper treatment are important for preventing sequelae such as suicide and substance use disorder. Studies have suggested that sleep duration is associated with anxiety disorder in adolescents. In the present study, we investigated the association between sleep quality and anxiety in a nationally representative sample of Korean adolescents. Methods: This cross-sectional study was conducted using data from the 2020 Korea Youth Risk Behavior Web-based Survey. The Generalized Anxiety Disorder-7 questionnaire was used to evaluate anxiety. The chi-square test was used to investigate and compare the general characteristics of the study population, and multiple logistic regression analysis was used to analyze the relationship between sleep quality and anxiety. Results: In both sexes, anxiety was highly prevalent in participants with poor sleep quality (adjusted odds ratio [aOR], 1.56; 95% confidence interval [CI], 1.43 to 1.71 in boys; aOR, 1.30; 95% CI, 1.19 to 1.42 in girls). Regardless of sleep duration, participants with poor sleep quality showed a high aOR for anxiety. Conclusions: This study identified a consistent relationship between sleep quality and anxiety in Korean adolescents regardless of sleep duration.
Oh, Hyunkyu,Sim, Jinsook,Ju, Sang-Yong American Chemical Society 2013 Langmuir Vol.29 No.35
<P>Binding affinity and thermodynamic understanding between a surfactant and carbon nanotube is essential to develop various carbon nanotube applications. Flavin mononucleotide-wrapped carbon nanotubes showing a large redshift in optical signature were utilized to determine the binding affinity and related thermodynamic parameters of 12 different nanotube chiralities upon exchange with other surfactants. Determined from the midpoint of sigmoidal transition, the equilibrium constant (<I>K</I>), which is inversely proportional to the binding affinity of the initial surfactant-carbon nanotube, provided quantitative binding strengths of surfactants as SDBS > SC ≈ FMN > SDS, irrespective of electronic types of SWNTs. Binding affinity of metallic tubes is weaker than that of semiconducting tubes. The complex <I>K</I> patterns from semiconducting tubes show preference to certain SWNT chiralities and surfactant-specific cooperativity according to nanotube chirality. Controlling temperature was effective to modulate <I>K</I> values by 30% and enables us to probe thermodynamic parameters. Equally signed enthalpy and entropy changes produce Gibbs energy changes with a magnitude of a few kJ/mol. A greater negative Gibbs energy upon exchange of surfactant produces an enhanced nanotube photoluminescence, implying the importance of understanding thermodynamics for designing nanotube separation and supramolecular assembly of surfactant.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2013/langd5.2013.29.issue-35/la4022933/production/images/medium/la-2013-022933_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la4022933'>ACS Electronic Supporting Info</A></P>
Kim, Hyunkyu,Ko, Byung Ug,Shim, In-Bo,Lee, Bo Wha,Kim, Chul Sung IEEE 2015 IEEE transactions on magnetics Vol.51 No.11
<P>The BaCo2-xZnxFe16O27 (x = 0, 0.5, 1) samples were prepared by solid-state reaction method. The prepared samples are single-phased, and their crystal structures are determined to be hexagonal with a space group of P6(3)/mmc from Rietveld refinement analysis. The magnetic saturation values were increasing, and the values of coercivity were decreasing with increasing Zn contents. The experimentally measured temperature dependence of magnetization curves shows magnetic transitions. We have measured Mossbauer spectroscopy at various temperatures to investigate microscopic magnetic properties. We analyze the obtained spectra with the five magnetic sites of 4 f(VI), 6g + 4 f(VI), 4e(IV) + 4 f(IV), 12k(VI), and 2d(V). In addition, from the Mossbauer spectra, we notice the changes in the magnetic hyperfine field and electric quadrupole shift. The substituted Zn2+ ions are located at tetrahedral site, and increase the M-s. Curie temperatures were determined from zero-field-cooled magnetizations measurement.</P>
Magnetic properties of Nd-Ga-Fe<sub>bal</sub>-Nb-B alloy
Kim, Hyunkyu,Yong An, Sung,Ryong Choi, Kang,Choi, Moonhee,Sung Kim, Chul American Institute of Physics 2014 Journal of Applied Physics Vol.115 No.17
<P>Here, we have synthesized Nd-Ga-Fe-bal-Nb-B alloy by strip casting method. The crystalline and magnetic properties of sample were investigated with x-ray diffractometer (XRD), vibrating sample magnetometer (VSM), and Mossbauer spectrometer. The XRD pattern was analyzed with the Rietveld refinement method, indicating a tetragonal structure and the space group of P4(2)/mnm. The temperature dependence of zero-field cooled (ZFC) magnetization curve was measured under applied field at temperature ranging from 4.2 to 740 K. From the ZFC curve, Curie temperature and spin reorientation temperature are determined to be 615 K and 130 K, respectively. Also, Mossbauer spectra were measured at various temperatures ranging from 4.2 to 620 K. Each spectrum was fitted with 6-sextets for Fe site (8j(1), 8j(2), 16k(1), 16k(2), 4c, and 4e), and magnetic hyperfine field, Isomer shift, electric quadrupole shift, and area ratio values were obtained from the fit. We observed the change in slope of magnetic hyperfine field and electric quadrupole shift at 130 K while the Curie temperature was determined to be 615 K from the measurement of zero velocity counter, agreeing with the values obtained from VSM measurements. (C) 2014 AIP Publishing LLC.</P>