An Efficient and Regioselective Synthesis of 2,3-Disubstituted 6-Aminoquinoxaline Derivatives Using Alkoxylation and Microwave-assisted Sonogashira Coupling

Lee, Doohyun,Seo, Young Ho,Bae, Jong-Sup,Lee, Sangkyu,Lee, Tae Im,Gong, Young-Dae,Lee, Taeho Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.8

Role of moesin in HMGB1-stimulated severe inflammatory responses

Lee, Wonhwa,Kwon, Oh Kwang,Han, Min-Su,Lee, You-Mie,Kim, Shin-Woo,Kim, Kyung-Min,Lee, Taeho,Lee, Sangkyu,Bae, Jong-Sup Thieme 2015 Thrombosis and Haemostasis Vol.114 No.2

<B>Summary</B><P>Sepsis is a life-threatening condition that arises when the body’s response to infection causes systemic inflammation. High-mobility group box 1 (HMGB1), as a late mediator of sepsis, enhances hyper-permeability, and it is therefore a therapeutic target. Despite extensive research into the underlying mechanisms of sepsis, the target molecules controlling vascular leakage remain largely unknown. Moesin is a cytoskeletal protein involved in cytoskeletal changes and para-cellular gap formation. The objectives of this study were to determine the roles of moesin in HMGB1-mediated vascular hyperpermeability and inflammatory responses and to investigate the mechanisms of action underlying these responses. Using siRNA knockdown of moesin expression in primary human umbilical vein endothelial cells (HUVECs), moesin was found to be required in HMGB1-induced F-actin rearrangement, hyperpermeability, and inflammatory responses. The mechanisms involved in moesin phosphorylation were analysed by blocking the binding of the HMGB1 receptor (RAGE) and inhibiting the Rho and MAPK pathways. HMGB1-treated HUVECs exhibited an increase in Thr558 phosphorylation of moesin. Circulating levels of moesin were measured in patients admitted to the intensive care unit with sepsis, severe sepsis, and septic shock; these patients showed significantly higher levels of moesin than healthy controls, which was strongly correlated with disease severity. High blood moesin levels were also observed in cecal ligation and puncture (CLP)-induced sepsis in mice. Administration of blocking moesin antibodies attenuated CLP-induced septic death. Collectively, our findings demonstrate that the HMGB1-RAGE-moesin axis can elicit severe inflammatory responses, suggesting it to be a potential target for the development of diagnostics and therapeutics for sepsis.</P>

LC-MS/MS analysis of leelamine for pharmacokinetics study in ICR mice

Sangkyu Lee(이상규),Min Song(송민),Doohyun Lee(이두현),Taeho Lee(이태호) 환경독성보건학회 2013 한국독성학회 심포지움 및 학술발표회 Vol.2013 No.10

경량 연자성 소재의 군 시설물 적용 시 방사선 차폐효과 분석

이상규(Sangkyu Lee),이상민(Sangmin Lee),최경준(Gyoungjun Choi),이병학(Byounghwak Lee) 한국방사선학회 2021 한국방사선학회 논문지 Vol.15 No.2

본 연구의 목적은 경량 연자성 소재의 방사선 차폐 효과를 분석하여 군사시설에 대한 적용 가능성을 확인하는 것이다. 연자성 물질은 EMP 차폐에 효과적인 것으로 알려져 있다. 이 물질이 방사선 차폐에도 효과적이라면 군 방호에 효과적으로 적용이 가능할 것으로 예상된다. 이에 본 연구에서는 감마선 차폐 효과를 확인하기 위해 Cs-137 및 Co-60 선원을 사용하여 실험을 수행하였으며, 중성자 차폐 효과를 평가하기 위해 Monte Carlo N-Particle (MCNP) 모델링을 적용하였다. 그 결과 연자성 소재의 두께가 증가함에 따라 감마선과 중성자의 선형 감쇠 법칙에 의한 차폐성능이 향상됨을 확인할 수 있었다. 따라서 연자성 소재를 군사용 구조물 등에 적용할 경우에 방사선 차폐에 효과적이라는 것을 확인하였다. The purpose of this research is to analyze the radiation shielding effect of soft magnetic material to confirm the applicability to the military facilities. The soft magnetic material is known to be effective in shielding EMP. If this material is also effective in radiation shielding, it is expected that it has a lot of applicability in military protection. In particular, this material contains boron, so it will be effective in shielding neutrons. In this research, experiments were conducted using Cs-137 and Co-60 sources to check the gamma ray shielding effect. In addition, the Monte Carlo N-Particle(MCNP) modeling was applied to evaluate the gamma ray and neutron shielding effect of a military command tent. As a result, as the soft magnetic thickness increased, the shielding performance improved according the linear attenuation law of gamma ray and neutron. Therefore, this research verified that the application of soft magnetic material for military purposes in radiation shielding would be effective.

원자력발전소용 안전등급 케이블의 경년열화에 따른 연소 및 연기특성 분석

이석희(Seok-Hui Lee),김민호(Min-Ho Kim),이상규(Sangkyu Lee),이주은(Ju-Eun Lee),이민철(Min-Chul Lee) 한국화재소방학회 2021 한국화재소방학회논문지 Vol.35 No.1

본 연구에서는 원자력 발전소에서 사용되는 안전등급 케이블을 대상으로 경년열화에 따른 연소 및 연기특성을콘 칼로리미터 시험을 통해 분석하였다. 열발생률의 1st peak 구간인 초기 특성의 경우, 비열화 케이블이 열화 케이블에 비해 20-50 kW/㎡ 높게 측정되었으나, 2nd peak인 중/후기에는 열화에 따른 난연성능의 저하에 기인하여 비열화케이블에 비해 열화 케이블들이 높게 측정되었다. 또한, Char 층이 불안정하게 형성됨에 따라 char 층의 유지시간이비열화 케이블에 비해 열화 케이블들이 약 200 s 단축됨을 확인하였다. 총발열량은 열화 케이블이 비열화 케이블에비해 약 1.4배 높게 측정되었다. 연기특성의 경우, 연기발생률은 열발생률과, 총 연기발생량은 총발열량과 비슷한 양상을 띄며, 총 연기발생량은 열화 케이블이 비열화 케이블보다 높게 측정되었다. 연기인자는 열화 기간이 증가함에따라 증가하는 경향성을 보였으며, 4년 이상 열화된 케이블들은 비열화 케이블에 비해 약 1.76-2.0배 정도 차이가 났다. 따라서 경년열화가 진행된 케이블일수록 열 및 연기방출의 위험성이 증가하였다. In this study, combustion and smoke characteristics according to the aging of class 1E cables in nuclear power plants wereanalyzed through a cone calorimeter test. In the case of combustion characteristics, during the early period, which was thefirst peak of the heat release rate, the peak value of the non-aged cable was higher by approximately 20-50 kW/㎡ than thatof aged cables. However, in the mid-late periods, which was the second peak, the value of the aged cables were higher thanthe non-aged cable due to the decrease in flame retardant performance with aging deterioration. In addition, the duration ofthe char layer of the aged cables was shortened by 200 s than that of the non-aged cables due to the unstable formation ofchar layer. The total heat release measured was approximately 1.4 times higher in the aged cables than in the non-aged cables. In the case of smoke characteristics, the smoke production rate and total smoke release show a similar trend with the heatrelease rate and total heat release. The total smoke release of the aged cables was measured to be higher than that of thenon-aged cables. The tendency of the smoke factor increased with aging deterioration, and the values of the smoke factor inthe aged cables beyond 4 years were approximately 1.76-2.0 times different from those in the non-aged cables. Consequently,the smoke risk increased with aging deterioration. Therefore, the risk of heat and smoke release increased as aging progressed.

High-Temperature Stable Anatase Titanium Oxide Nanofibers for Lithium-Ion Battery Anodes

Lee, Sangkyu,Eom, Wonsik,Park, Hun,Han, Tae Hee American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.30

<P>Control of the crystal structure of electrochemically active materials is an important approach to fabricating high-performance electrodes for lithium-ion batteries (LIBs). Here, we report a methodology for controlling the crystal structure of TiO2 nanofibers by adding aluminum isopropoxide to a common sol-gel precursor solution utilized to create TiO2 nanofibers. The introduction of aluminum cations impedes the phase transformation of electrospun TiO2 nanofibers from the anatase to the rutile phase, which inevitably occurs in the typical annealing process utilized for the formation of TiO2 crystals. As a result, high temperature stable anatase TiO2 nanofibers were created in which the crystal structure was well-maintained even at high annealing temperatures of up to 700 degrees C. Finally, the resulting anatase TiO2 nanofibers were utilized to prepare LIB anodes, and their electrochemical performance was compared to pristine TiO2 nanofibers that contain both anatase and rutile phases. Compared to the electrode prepared with pristine TiO2 nanofibers, the electrode prepared with anatase TiO2 nanofibers exhibited excellent electrochemical performances such as an initial Coulombic efficiency of 83.9%, a capacity retention of 89.5% after 100 cycles, and a rate capability of 48.5% at a current density of 10 C (1 C = 200 mA g(-1)).</P>

Hymenobacter seoulensis sp. nov., isolated from river water

Lee, Jae-Jin,Lee, Yeon-Hee,Park, Su-Jin,Lee, Seung-Yeol,Park, Sangkyu,Kim, Myung Kyum,Ten, Leonid N,Jung, Hee-Young Microbiology Society 2017 International journal of systematic and evolutiona Vol.67 No.3

Ginsenosides Inhibit HMGB1-induced Inflammatory Responses in HUVECs and in Murine Polymicrobial Sepsis

Lee, Wonhwa,Ku, Sae-Kwang,Jeong, Tae Cheon,Lee, Sangkyu,Bae, Jong-Sup Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.10

Asian ginseng is used as a treatment for cardiovascular diseases, ischemia, and cancers. High mobility group box 1 (HMGB1) protein acts as a late mediator of severe vascular inflammatory conditions. However, the effect of ginsenosides from Asian ginseng on HMGB1-induced inflammatory responses has not been studied. We addressed this question by monitoring the effects of ginsenoside treatment on lipopolysaccharide (LPS) and cecal ligation and puncture (CLP)-mediated release of HMGB1, and HMGB1-mediated regulation of proinflammatory responses. Ginsenoside treatment suppressed LPS-mediated release of HMGB1 and HMGB1-mediated cytoskeletal rearrangements. Ginsenosides also inhibited HMGB1-mediated inflammatory responses. In addition, ginsenosides inhibited the production of tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) and activation of protein kinase B (Akt), nuclear factor-${\kappa}B$ (NF-${\kappa}B$), and extracellular-regulated kinases (ERK) 1/2 by HMGB1. Ginsenosides also decreased CLP-induced release of HMGB1, production of interleukin (IL) $1{\beta}/6$, and mortality. These results suggested that ginsenosides may be potential therapeutic agents for treatment of vascular inflammatory diseases through inhibition of the HMGB1 signaling pathway.

Surface-Coverage-Dependent Cycle Stability of Core-Shell Nanostructured Electrodes for Use in Lithium Ion Batteries

Lee, Sangkyu,Ha, Jaehwan,Cheng, Huanyu,Lee, Jung Woo,Jang, Tae Sik,Jung, Yeon-Gil,Huang, Yonggang,Rogers, John A.,Paik, Ungyu Wiley Blackwell (John Wiley Sons) 2014 ADVANCED ENERGY MATERIALS Vol.4 No.1

What Explains the Idiosyncratic Volatility in the Korean Stock Market?

Sangkyu Lee,Anna Moon 한국재무학회 2013 한국재무학회 학술대회 Vol.2013 No.05

Using the Fama and French (1993) three-factor model, this paper provides an explanation for the variation of idiosyncratic return in the Korean stock market over the period of 1990-2012. There had been an upward trend until 1999 in idiosyncratic volatility and its trend has been reversed afterwards. Our analysis yields three main results. Firstly, it appears that all four explanatory variables, two fundamentals related variables of the variance of return on equity and a proxy of growth options and two trading volume related variables of trading volume and foreign ownership ratio, explain considerable proportion of idiosyncratic return variation. Most interestingly, foreign investors have stabilizing effect on firm-specific risk in the Korean stock market. Secondly, a firm’s characteristics such as size and export orientation exert some influence on idiosyncratic volatility. Lastly, the absolute and relative explanatory powers of the four explanatory variables vary through time and diminish as the sample period ends, implying the need to search for further explanatory variables.