Liquid Crystal Droplet Patterns to Monitor Catalase Activity at Femtomolar Levels

Stephanie Yoon,장창현 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.9

Catalase (CAT) decomposes hydrogen peroxide that is toxic to the body. In this study, simple and sensitive detector has been developed for observing catalase activity using liquid crystal droplet system. Microscale LC droplet patterns are formed by spreading aldehyde-doped nematic liquid crystal on pre-treated glass slides. When hydrogen peroxide is added, aldehyde is oxidized and amphiphiles are formed. Dodecanoates cause the pattern to transit from bright to dark as they self-assemble to form a carboxyalte monolayer at the interface. When a drop of pre-incubated CAT and hydrogen peroxide mixture is placed onto the pattern, bright fan-shape is observed. This planar optical appearance indicates that catalase has decomposed hydrogen peroxide. Compared to the detectors that have been previously developed, this system is more sensitive with detection limit of 1fM. This research suggests further studies to be on LC droplet patterning to develop highly sensitive and methodologically simple sensors for various chemicals.

Liquid Crystal Droplet Patterns to Monitor Catalase Activity at Femtomolar Levels

Yoon, Stephanie,Jang, Chang-Hyun Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.9

Catalase (CAT) decomposes hydrogen peroxide that is toxic to the body. In this study, simple and sensitive detector has been developed for observing catalase activity using liquid crystal droplet system. Microscale LC droplet patterns are formed by spreading aldehyde-doped nematic liquid crystal on pre-treated glass slides. When hydrogen peroxide is added, aldehyde is oxidized and amphiphiles are formed. Dodecanoates cause the pattern to transit from bright to dark as they self-assemble to form a carboxyalte monolayer at the interface. When a drop of pre-incubated CAT and hydrogen peroxide mixture is placed onto the pattern, bright fan-shape is observed. This planar optical appearance indicates that catalase has decomposed hydrogen peroxide. Compared to the detectors that have been previously developed, this system is more sensitive with detection limit of 1fM. This research suggests further studies to be on LC droplet patterning to develop highly sensitive and methodologically simple sensors for various chemicals.

Effects of Korean and US consumers’ ethical consumption values on ethical dining-out behavior : The mediating role of perceived restaurant ethical performance

Stephany Hwang,Jiyoung Yoon 한국관광연구학회 2020 관광연구저널 Vol.34 No.10

Genome-wide hepatic DNA methylation changes in high-fat diet-induced obese mice

AhRam Yoon,Stephanie A. Tammen,Soyoung Park,Sung Nim Han,Sang-Woon Choi 한국영양학회 2017 Nutrition Research and Practice Vol.11 No.2

BACKGROUND/OBJECTIVES: A high-fat diet (HFD) induces obesity, which is a major risk factor for cardiovascular disease and cancer, while a calorie-restricted diet can extend life span by reducing the risk of these diseases. It is known that health effects of diet are partially conveyed through epigenetic mechanism including DNA methylation. In this study, we investigated the genome-wide hepatic DNA methylation to identify the epigenetic effects of HFD-induced obesity. MATERIALS AND METHODS: Seven-week-old male C57BL/6 mice were fed control diet (CD), calorie-restricted control diet (CRCD), or HFD for 16 weeks (after one week of acclimation to the control diet). Food intake, body weight, and liver weight were measured. Hepatic triacylglycerol and cholesterol levels were determined using enzymatic colorimetric methods. Changes in genome-wide DNA methylation were determined by a DNA methylation microarray method combined with methylated DNA immunoprecipitation. The level of transcription of individual genes was measured by real-time PCR. RESULTS: The DNA methylation statuses of genes in biological networks related to lipid metabolism and hepatic steatosis were influenced by HFD-induced obesity. In HFD group, a proinflammatory Casp1 (Caspase 1) gene had hypomethylated CpG sites at the 1.5-kb upstream region of its transcription start site (TSS), and its mRNA level was higher compared with that in CD group. Additionally, an energy metabolism-associated gene Ndufb9 (NADH dehydrogenase 1 beta subcomplex 9) in HFD group had hypermethylated CpG sites at the 2.6-kb downstream region of its TSS, and its mRNA level was lower compared with that in CRCD group. CONCLUSIONS: HFD alters DNA methylation profiles in genes associated with liver lipid metabolism and hepatic steatosis. The methylation statuses of Casp1 and Ndufb9 were particularly influenced by the HFD. The expression of these genes in HFD differed significantly compared with CD and CRCD, respectively, suggesting that the expressions of Casp1 and Ndufb9 in liver were regulated by their methylation statuses.

Single Chromosome Based Physical Mapping of Human Chromosome 12

Lau, Stephanie,Marondel, Lvone,Yoon Kim, Sung-Joo,Chang, Joan,Montgomery, Kate,Renault, Beatrice,Kucherlapati, Raiu 가톨릭 의과학연구원 1997 가톨릭 의과학연구원 국제학술대회 Vol.1 No.-

Human chromosome 12 constitutes approximately 4.5% of the human genome and has an estimated size of 130 megabases. We have initiated an effort to construct an integrated high resolution physical, genetic, and cytogenetic map of this chromosome using an STS-content based strategy with overlapping YACs. The foundation for this map is the first generation physical map presented by Cohen et al.

Effects of Korean and US Consumers’ Environmental Concern on Green Restaurant Patronage Intention

Nami Joo,Stephany Sewon Hwang,Jiyoung Yoon 동아시아식생활학회 2018 동아시아식생활학회지 Vol.28 No.4

Characterization of an H4N2 influenza virus from Quails with a multibasic motif in the hemagglutinin cleavage site

Wong, Sook-San,Yoon, Sun-Woo,Zanin, Mark,Song, Min-Suk,Oshansky, Christine,Zaraket, Hassan,Sonnberg, Stephanie,Rubrum, Adam,Seiler, Patrick,Ferguson, Angela,Krauss, Scott,Cardona, Carol,Webby, Richard Elsevier 2014 Virology Vol.468 No.-

<P><B>Abstract</B></P> <P>The cleavage motif in the hemagglutinin (HA) protein of highly pathogenic H5 and H7 subtypes of avian influenza viruses is characterized by a peptide insertion or a multibasic cleavage site (MBCS). Here, we isolated an H4N2 virus from quails (Quail/CA12) with two additional arginines in the HA cleavage site, PEK<B>RR</B>TR/G, forming an MBCS-like motif. Quail/CA12 is a reassortant virus with the HA and neuraminidase (NA) gene most similar to a duck-isolated H4N2 virus, PD/CA06 with a monobasic HA cleavage site. Quail/CA12 required exogenous trypsin for efficient growth in culture and caused no clinical illness in infected chickens. Quail/CA12 had high binding preference for α2,6-linked sialic acids and showed higher replication and transmission ability in chickens and quails than PD/CA06. Although the H4N2 virus remained low pathogenic, these data suggests that the acquisition of MBCS in the field is not restricted to H5 or H7 subtypes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An H4N2 influenza virus with a multibasic cleavage site in the hemagglutinin protein was isolated from quails. </LI> <LI> This virus remained lowly pathogenic in chickens and required trypsin for <I>in vitro</I> growth. </LI> <LI> This virus showed higher preference for mammalian-type sialic acid receptors. </LI> <LI> This virus transmitted better in chicken than a duck-origin H4N2 virus. </LI> </UL> </P>

Combined effect of photobiomodulation with a matrix metalloproteinase inhibitor on the rate of relapse in rats

Lee, Sang-Hyun,Kim, Kyung-A,Anderson, Stephanie,Kang, Yoon-Goo,Kim, Su-Jung The Angle Orthodontist 2016 The Angle orthodontist Vol.86 No.2

<B>ABSTRACT</B><B>Objective: </B><P>To investigate combined effect of photobiomodulation with a matrix metalloproteinase (MMP) inhibitor on the relapse rate in relation to MMP expression in rats.</P><B>Materials and Methods: </B><P>Fifty-two rats were divided into four groups according to the treatment modality: control group, irradiation group, doxycycline group, and irradiation with doxycycline group. During a relapse period of 5 days after orthodontic movement, maxillary central incisors were treated by low-level laser therapy (LLLT) as a photobiomodulation and/or doxycycline as a synthetic MMP inhibitor. Relapse rate was evaluated in association with MMP expression at the gene and protein levels.</P><B>Results: </B><P>Relapse rates were increased by LLLT (1.57-fold) and decreased by doxycycline (0.83-fold) compared with the control, showing positive correlation with the levels of expression for all MMPs in the periodontal ligament (PDL). LLLT concomitant with doxycycline administration resulted in no significant differences of relapse rate and MMP expression from the control.</P><B>Conclusions: </B><P>The combined effect of photobiomodulation with an MMP inhibitor around the relapsing teeth proved to be antagonistic to PDL remodeling activity during relapse. This study suggests a basis for developing a novel biologic procedure targeting the MMP-dependent PDL remodeling to control the relapse rate.</P>

상변화물질을 이용한 PMMA 복합필름의 방열 성능 향상에 관한 연구

권준혁,윤범용,조승현,김형익,김동현,박경의,서종환,Kwon, Junhyuk,Yoon, Bumyong,Cho, Seung-hyun,Lee, Stephanie K.,Kim, Hyung-ick,Kim, Donghyun,Park, Kyungui,Suhr, Jonghwan 한국복합재료학회 2017 Composites research Vol.30 No.5

본 연구에서는 전자기기 사용에 이슈가 되고 있는 발열 문제를 해결하고자 상변화물질(PCM)의 잠열 특성을 이용하여 폴리메틸메타크릴레이트(PMMA) 복합필름을 제조하고 방열 성능을 평가하였다. 이를 위해 용융온도가 서로 다른 두 가지의 상변화물질을 사용하여 제작한 PCM/PMMA 복합필름의 열적 특성을 비교 분석하여 다양한 사용조건에 따른 유효성을 검증하였고, Compression Molding 방법과 PCM Paste Sealing 방법에 따른 PCM/PMMA 복합필름의 방열 특성을 비교 분석하여 최대의 방열 효과를 달성할 수 있는 최적의 방법을 도출하였다. 또한 PCM/PMMA 복합필름의 방열 성능을 최대화하기 위해 열전도율이 높은 흑연과 그래핀을 추가로 적층하여 제조한 Hybrid 복합필름의 열적 특성을 분석하였고, 이들을 통해 향상된 방열 성능을 실험적으로 검증하였다. 본 연구를 통해 개발된 방열 성능이 우수한 복합필름은 다양한 전자기기에 활용되어 발열 문제를 효과적으로 해결할 수 있을 것으로 기대된다. The focus of this study is to experimentally investigate the heat dissipation characteristics of poly (methyl methacrylate) (PMMA) composite films with phase change materials (PCM) to resolve heat build-up problems encountered in various electronic devices. In this study, two different types of phase change materials were used to fabricate the composite films by compression molding method and PCM paste sealing method then compared. It was observed in this study that the heat dissipation capability of PCM/PMMA composite films was remarkably enhanced by applying graphite sheet or graphene film into the composite due to their high thermal conductivity. These PCM/ PMMA composite films were attached on the hot spot inside smart phone and tested its surface temperature change according to time. The heat dissipation capability of PCM/PMMA composite film incorporated smart phone was increased 154% and hybrid PCM/PMMA composite film incorporated smart phone was increased 286% over the reference, respectively.

Complexity science of multiscale materials via stochastic computations

Liu, Wing Kam,Siad, Larbi,Tian, Rong,Lee, Sanghoon,Lee, Dockjin,Yin, Xiaolei,Chen, Wei,Chan, Stephanie,Olson, Gregory B.,Lindgen, Lars-Erik,Horstemeyer, Mark F.,Chang, Yoon-Suk,Choi, Jae-Boong,Kim, Yo John Wiley Sons, Ltd. 2009 International Journal for Numerical Methods in Eng Vol.80 No.6

<P>New technological advances today allow for a range of advanced composite materials, including multilayer materials and nanofiber-matrix composites. In this context, the key to developing advanced materials is the understanding of the interplay between the various physical scales present, from the atomic level interactions to the microstructural composition and the macroscale behavior. Using the developing ‘multiresolution data sets mechanics’, the ‘predictive science-based governing laws of the materials microstructure evolutions’ are derived and melted into a ‘stochastic multiresolution design framework.’ Under such a framework, the governing laws of the materials microstructure evolution will be essential to assess, across multiple scales, the impact of multiscale material design, geometry design of a structure, and the manufacturing process conditions, by following the cause–effect relationships from structure to property and then to performance.</P><P>The future integrated multiscale analysis system will be constructed based on a probabilistic complexity science-based mathematical framework. Its verification, validation and uncertainty quantification are done through carefully designed experiments, and the life-cycled materials design for products design and manufacturing is performed through the use of petascale computing. The various techniques of microstructure reconstruction result in the generation of model microstructures that, at some level, has the same statistical properties as the real heterogeneous media. Having reconstructed the heterogeneous medium, one can then evaluate its effective properties via direct numerical simulation and compare these values with experimentally measured properties of the actual medium. The proposed analysis will be dynamic in nature to capture the multi-stage historical evolvement of material/structure performance over the life span of a product. In addition to providing more accurate assessment of structure performance with stochastic multiscale analysis, our development will provide the capability of predicting structure failures and system reliability to enable more reliable design and manufacturing decisions in product development. Copyright © 2009 John Wiley & Sons, Ltd.</P>