Synthesis of Chroman-2-carboxylic Acid N-(substituted)Pheny-lamides and Their Inhibitory Effect on Nuclear $Factor-{\kappa}B$ ($NF-{\kappa}B$) Activation

Kwak, Jae-Hwan,Won, Sun-Woo,Kim, Tae-Jeong,Roh, Eun-Mi-Ri,Kang, Han-Young,Lee, Hyo-Won,Jung, Jae-Kyung,Hwang, Bang-Yeon,Kim, Young-Soo,Cho, Jung-Sook,Lee, Hee-Soon 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.2

A series of chroman-2-carboxylic acid N-(substituted)phenylamides (2a-s, 3a-j) were synthesized. Their ability to inhibit nuclear $factor-{\kappa}B$ ($NF-{\kappa}B$) activity was evaluated in lipopolysaccharide (LPS)-stimulated macrophage RAW 264.7 cells and their antioxidant activity was examined. $NF-{\kappa}B$ inhibition by chroman compounds was not related to their antioxidant activity. Compounds with -H,$-NO_2$ monosubstituents and $-OCH_3,\;-CF_3$ disubstituents on the phenyl ring were poor inhibitors of $NF-{\kappa}B$ activity. Compounds with $-CH_3,\;-CF_3,\;-CI$ monosubstituents or -CI, $-CH_3$ disubstituents exhibited moderate to good $NF-{\kappa}B$ activity inhibition $(IC_{50}:\;18.2-95.8\;{\mu}M)$. The most active $NF-{\kappa}B$ inhibitor, 2s, contained a 4-CI $(IC_{50}:\;18.2\;{\mu}M)$ substituent on the phenyl ring and was slightly more potent than the compound KL-1156 (1) $(IC_{50}:\;43.9\;{\mu}M)$.

Precoder Design and Capacity Analysis for Multi-Antenna Full-Duplex Relay

KWAK, Young-Woo,LEE, Jong-Ho,KIM, Yong-Hwa,KIM, Seong-Cheol 'Institute of Electronics, Information and Communi 2012 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.eb95 No.7

Cerebral Artery Dissection: Spectrum of Clinical Presentations Related to Angiographic Findings

Kwak, Jae Hyuk,Choi, Jin Woo,Park, Hee Jung,Chae, Eun Young,Park, Eun Suk,Lee, Deok Hee,Suh, Dae Chul Korean Society of Interventional Neuroradiology 2011 Neurointervention Vol.6 No.2

<P><B>Purpose</B></P><P>Cerebral arterial dissections are recognized as a common cause of stroke. However, few studies have reported on the distribution of cerebral arterial dissection and angiographic pattern related to the presenting clinical symptom pattern. We analyzed the distribution of cerebral artery dissection along with angiographic and clinical presenting a pattern as depicted on angiograms.</P><P><B>Materials and Methods</B></P><P>From January 2000 to January 2007, 133 arterial dissection patients admitted to our institutes were retrospectively reviewed. The characteristic angiographic findings of all cerebral arteries were carefully evaluated on 4-vessel angiograms. The male-female ratio was 77: 56 and the mean age was 51 years. According to the angiographic finding depicting the location of the dissection plane in the arterial wall, we categorized to steno-occlusive, aneurysmal, combined and unclassifiable pattern. In each dissection pattern, we evaluated presenting symptoms and presence of infarction or hemorrhage.</P><P><B>Results</B></P><P>The most common symptom on presentation was headache (47%), followed by motor weakness of arm or leg (31%), dysarthria/aphasia (19%) and vertigo (16%). The most common angiographic pattern was steno-occlusive (46%), followed by combined (steno-occlusive and aneurismal) (27%) and aneurysmal (22%) patterns. Steno-occlusive pattern was most commonly related to infarction (33/61, 54%) in contrast that aneurysmal pattern was most frequently related to subarachnoid hemorrhage (SAH) (7/29, 24%). The most frequent abnormality in patients with dissection of the intradural vertebral arteries including posterior cerebral artery (PCA) was SAH (23/70, 33%), followed by infarction. Infarction was the most common abnormality in patients with the extradural and intradural carotid arteries, and the extradural vertebral artery.</P><P><B>Conclusion</B></P><P>In contrast that the extradural arterial dissections tended to result in ischemia with steno-occlusive pattern, the intradural arterial dissections tended to result in SAH with aneurysmal type, especially in the vertebral artery. Dissection requires combined analysis of angiographic pattern and type of stroke depending on the location.</P>

안전조치 사찰을 위한 휴대형 HPGe 검출기 시제품 성능평가 실험

Kwak, Sung-Woo,Ahn, Gil Hoon,Park, Iljin,Ham, Young Soo,Dreyer, Jonathan 대한방사선방어학회 2014 방사선방어학회지 Vol.39 No.1

IAEA는 핵물질 계량 관리 검사를 위해 다양한 방사선 검출기를 사용하고 있다. 주로 HPGe, NaI(Tl), CZT 등이 사용되며, 정확한 측정이 요구되는 검사에는 고분해능 HPGe 검출기 활용도가 높다. HPGe 검출기는 추가적인 냉각장치로 인하여 부피가 크고 무거우며, 사용하기 전에 충분히 냉각시켜야 하기 때문에 측정의 준비 시간이 많이 걸린다는 단점이 있다. 이러한 문제점을 해결하기 위해 가볍고 짧은 사용 전 냉각이 요구되는 휴대형 HPGe가 개발되었다. 본 논문은 개발된 휴대형 HPGe 검출기 시제품을 실제 IAEA 사찰 현장에 적용하여 얻은 성능평가 결과를 기술한다. 휴대형 HPGe로 얻은 방사선 스펙트럼은 핵물질 종류와 농축도에 따라 다른 특징을 보였고, 또한 $^{235}U$과 $^{238}U$의 붕괴 계열에서 방출되는 감마선 및 우라늄의 특성 x-선 차이도 확인할 수 있었다. 그리고 휴대형 HPGe 검출기 시제품으로 측정한 농축도는 핵물질 종류에 따라 실제값과 9 ~ 27%의 상대적 오차를 보였다. 휴대형이라는 소형 검출기의 한계 때문에 일부 핵물질은 IAEA에서 요구하는 정확도를 만족시키지 못하는 경우도 있었지만 향후 추가적인 연구의 수행으로 이러한 문제점은 해결 가능할 것으로 판단된다. 본 논문은 새로운 휴대형 HPGe 검출기를 안전조치에 적용한 사례와 측정한 스펙트럼을 농축도 분석 코드로 분석한 결과를 다룬다. 따라서 국내 원자력시설의 우라늄 농축도 검증을 위한 IAEA 안전조치 사찰 결과를 분석한 논문이 별로 발표되지 않은 상황에서, 본 논문은 안전조치 검사 결과 분석에도 유익할 것으로 판단된다. 개발된 방사선 검출기의 개선 사항도 함께 논의하였으므로 향후 관련 분야 방사선 검출기 개발에도 기여할 것으로 예상된다. IAEA has employed various types of radiation detectors - HPGe, NaI, CZT - for accountancy of nuclear material. Among them, HPGe has been mainly used in verification activities required for high accuracy. Due to its essential cooling component(a liquid-nitrogen cooling or a mechanical cooling system), it is large and heavy and needs long cooling time before use. New hand-held portable HPGe has been developed to address such problems. This paper deals with results of performance evaluation test of the new hand-held portable HPGe prototype which was used during IAEA's inspection activities. Radioactive spectra obtained with the new portable HPGe showed different characteristics depending on types and enrichments of nuclear materials inspected. Also, Gamma-rays from daughter radioisotopes in the decay series of $^{235}U$ and $^{238}U$ and characteristic x-rays from uranium were able to be remarkably separated from other peaks in the spectra. A relative error of enrichment measured by the new portable HPGe was in the range of 9 to 27%. The enrichment measurement results didn't meet partially requirement of IAEA because of a small size of a radiation sensing material. This problem might be solved through a further study. This paper discusses how to determine enrichment of nuclear material as well as how to apply the new hand-held portable HPGe to safeguard inspection. There have been few papers to deal with IAEA inspection activity in Korea to verify accountancy of nuclear material in national nuclear facilities. This paper would contribute to analyzing results of safeguards inspection. Also, it is expected that things discussed about further improvement of a radiation detector would make contribution to development of a radiation detector in the related field.

Generation and reactivities of methoxyphenylsilylene

Kwak, Young-Woo,Jeong, Ill-Hyeon,Ko, Jae-You,Boo, Bong Hyun 충남대학교 기초과학연구소 1993 연구논문집 Vol.13 No.-

From the vacuum pyrolysis of 1,1-dimethoxy-1-phenyl-2,2,2-trimethyldisilane (Ⅰ) in the presence of 2,3-dimethyl-1,3-butadiene, two major products, 1-methoxy-1-phenyl-3,4-dimethyl-1-silacyclopent-3-ene (Ⅱ) and 1-phenyl-3,4-dimethyl-1-silacyclopent-3-ene (Ⅲ) along with methoxytrimethylsilane have been observed. Methoxyphenylsilylene has been suggested as the primary intermediate that may produce phenylsilylene by the extrusion of formaldehyde from Ph-S¨i-OMe. These two silylenes may be responsible for the formation of products Ⅱ and Ⅲ. It is proposed that the phenylsilylene was generated from the [3→2+1] cycloelimination of an intermediate of the 2-phenyloxasilacyclopropane (PhHSi-O-CH_2) which can arise from a possible intramolecular silylene insertion into the C-H bond of the methoxy group in Ph-S¨i-OMe. A labelling experiment employing a partially deuteriated precursor of 1,1-dimethoxy-d_6-1-phenyl-2,2,2-trimethyldisilane (I-d) checked whether or not product Ⅲ is a secondary product of the [3→2+1] cycloelimination of the oxasilacyclopropane. As expected, 1-methoxy-d_3-phenyl-3,4-dimethyl-1-silacyclopent-3-ene (Ⅱ-d) and 1-deuterio-1-phenyl-3,4-dimethyl-1-silacyclopent-3-ene (Ⅲ-d) are the major products of pyrolysis of the deuteriated precursor (Ⅰ-d) in the presence of the same trapping agent. The intermediacy to phenylsilylene of the oxacyclopropane in the decomposition of alkoxyphenylsilylene is supported by the observation that pyrolysis of 1,1-diethoxy-1-phenyl-2,2,2-trimethyldisilane (Ⅳ) in the presence of the same trapping agent produces 1-phenyl-3,4-dimethyl-1-silacyclopentene (Ⅲ) as the major product along with a trace of 1-ethoxy-1-phenyl-3,4-dimethyl-1-silacyclopent-3-ene (Ⅴ). A temperature dependence experiment elucidated the energetics of the conversion of Ph-S¨i-OMe to Ph-S¨i-H. As the reaction temperature increases, the product ratio (Ⅲ/Ⅱ) increases, indicating that dissociation of Ph-S¨i-OMe into Ph-S¨i-H and HCHO may be an activated process, which is consistent with the MNDO semiempirical calculation.

Organocatalytic Asymmetric Intramolecular Allylic Substitutions of Morita-Baylis-Hillman Acetates: Synthesis of Chiral 2-(α-Methylene)-Pyrrolidines

Kwak, Mi-Young,Kwon, Su-Hyun,Cho, Chang-Woo Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.11

Preparation Method of Co₃O₄ Nanoparticles Using Ordered Mesoporous Carbons as a Template and Their Application for Fischer–Tropsch Synthesis

Kwak, Geunjae,Hwang, Jongkook,Cheon, Joo-Young,Woo, Min Hee,Jun, Ki-Won,Lee, Jinwoo,Ha, Kyoung-Su American Chemical Society 2013 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.117 No.4

<P>Co<SUB>3</SUB>O<SUB>4</SUB> nanoparticles (NPs) with a narrow particle size distribution were fabricated via a facile and novel method using mesoporous carbon materials (CMK-3, MSU-F-C) as sacrificial templates. The particle size distribution of the Co<SUB>3</SUB>O<SUB>4</SUB> NPs varied depending on the pore size of the templates. Synthesis of the NPs with concurrent complete removal of the templates was achieved at 593 K, which is lower than the temperatures utilized in previous reports. It was verified that the carbon template was decomposed by catalytic oxidation with cobalt and NO<SUB><I>x</I></SUB> species generated by thermal decomposition of the cobalt nitrate precursor in air. The prepared NPs, and particularly the Co<SUB>3</SUB>O<SUB>4</SUB> NPs synthesized from CMK-3, acted as excellent catalysts for the Fischer–Tropsch synthesis (FTS). The high catalytic performance was associated with the optimum particle size (6–10 nm) of the nanoparticles for FTS and enhanced reducibility.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2013/jpccck.2013.117.issue-4/jp3106698/production/images/medium/jp-2012-106698_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp3106698'>ACS Electronic Supporting Info</A></P>

Generation and Trapping of 2-Methyl-2-silanaphthalene

Kwak, Young-Woo,Lee, Jong-Bong,Lee, Kyung-Koo,Kim, Seong-Su,Boo, Bong Hyun 충남대학교 기초과학연구소 1994 연구논문집 Vol.14 No.-

There has been many reports of the generation and their reactions of silabenzene intermediate from the readily available allyl or chloro precursors. The intramolecular reacton of 1-methyl-2,3,4,5-tetraphenylsilacyclopentadienylmethlene to give silatoluene was reported by Anbo and Sekiguchi. West and coworkers reported the existence of the intermediacy of hexamethyl-1,4-disilabenzene. In 1978, Barton and Burns confirmed the first unambiguous generation and trapping of the silatoluene formed via a thermally induced retroene elimination of propene from the 1-allyl-1-methyl-1-silacy-clohexa-2,4-diene. There is precedent for the unsuccessful approach to produce 2-silanaphthalene intermediate from the thermolysis or photolysis of silyl diazo compound 1 in the presence of methanol.

Ultrasmall PtSn alloy catalyst for ethanol electro-oxidation reaction

Kwak, Da-Hee,Lee, Young-Woo,Han, Sang-Beom,Hwang, Eui-Tak,Park, Han-Chul,Kim, Min-Cheol,Park, Kyung-Won Elsevier 2015 Journal of Power Sources Vol.275 No.-

<P><B>Abstract</B></P> <P>To improve the electrocatalytic properties for an ethanol electro-oxidation reaction, modifications of Pt nanocrystallites have been used by alloying with other elements such as Ru, Sn, and Au. Here we demonstrate carbon supported Pt<SUB>3</SUB>Sn alloy electrocatalyst (Pt<SUB>3</SUB>Sn/C) synthesized using a thermal-decomposition method. The PtSn/C prepared by the present synthetic process shows a homogeneous distribution of ultrasmall alloy nanoparticles (∼2.5 nm) in the presence of Pt and Sn metallic states. At 0.45 V, the Pt<SUB>3</SUB>Sn/C (0.35 mA cm<SUP>−2</SUP>) exhibits much higher current density as compared with Pt/C (0.13 mA cm<SUP>−2</SUP>). In an electrochemical stability test, the Pt<SUB>3</SUB>Sn/C supported quite high current density and thus showed 3% current reduction after the stability test.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pt<SUB>3</SUB>Sn nanoparticles with an ultrasmall size of 2.5 nm were synthesized. </LI> <LI> Pt<SUB>3</SUB>Sn nanoparticles showed improved electrocatalytic activity and stability. </LI> <LI> The improved activity may be attributed to a well-defined alloy formation. </LI> </UL> </P>

Inhibition of Metarhizium anisopliae infection of Protaetia brevitarsis seluensis larvae using several effective microorganisms

Kwak, Kyu-Won,Kwon, Soon Woo,Nam, Sung-Hee,Park, Kwan-Ho,Kim, Eun-Sun,Lee, Hee-Sam,Choi, Ji-Young,Han, Myung-Sae Korean Society of Sericultural Science 2018 International Journal of Industrial Entomology Vol.36 No.1

The purpose of this study was to determine the best method for minimizing the occurrence of Metarhizium anisopliae infection of Protaetia brevitarsis seluensis during mass breeding on agricultural farms. There is a high demand for the use of P. b. seluensis larvae in animal feed and as food for humans. However, mass breeding results in the entomopathogenic fungal (usually M. anisopliae) infection of P. b. seluensis. A mixture of microorganisms (Bacillus subtilis, Lactobacillus plantarum, and Saccharomyces cerevisiae) delayed fungal infection by M. anisopliae, which infected fewer P. b. seluensis when the microorganism mixture was added to sawdust as feed for P. b. seluensis. When sawdust with the effective microorganisms (EM) was given to P. b. seluensis for 30 d, their mortality rate was approximately 35 % less than that of the control group, which was fed sawdust without the EM. In addition, the growth of M. anisopliae on agar media spread with each bacterium as inhibited by up to 80 % more than those spread with 4 % sodium hypochlorite, which is a harmless fungal inhibitor generally used in agricultural farms for disinfection.