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InGaAs/GaAs quantum well intermixing using proton irradiation for non-absorbing mirror
Ye Seul Yun,SangHyeon Kim,Han-Youl Ryu,Min-Su Park,Hojin Jang,Jonghan Song,Weon Cheol Lim,Young Jun Chang,Won Jun Choi 한국물리학회 2016 Current Applied Physics Vol.16 No.9
We report a proton irradiation-induced intermixing on InGaAs/GaAs quantum well (QW) heterostructures with thick upper cladding layers. Proton irradiation was performed with different dose, followed with annealing. Proton irradiated and annealed sample shows the blue-shift of the photoluminescence (PL) spectra and the blue-shift energy was increased up to about 30 meV with increasing dose, but was insensitive to the annealing temperature. Finally, we calculated that the relative absorption coefficient at the laser wavelength for the irradiated sample with dose of 1 1016/cm2 was 0.045, suggesting such proton irradiation-induced intermixing is a promising approach for fabricating non-absorbing mirror.
Ultrathin metamaterial-based perfect absorbers for VHF and THz bands
Ye Seul Yun,SangHyeon Kim,Han-Youl Ryu,Min-Su Park,V. D. Lam,J.G. Yang,Y. P. Lee 한국물리학회 2016 Current Applied Physics Vol.16 No.9
An ultrathin and angularly stable metamaterial perfect absorber (MPA) is demonstrated for VHF-band using four connected split-square resonators structure and low-cost fabrication process. The total incoming energy of electromagnetic wave (at 250 MHz) is consumed inside the efficient thickness, which is 240 times smaller than the absorption wavelength of MPA. Our MPA works well for a very wide range of incident angle up to 45 of electromagnetic wave and exhibits the polarization-independent behavior. Furthermore, by scaling the initial design and integrating a ferroelectric material (strontium titanate), a thermo-tunable ultrathin MPA is realized in the THz region. At room temperature (300 K), the thickness of THz MPA reaches roundly 1/300 of the working wavelength. In addition, a fractional frequency shift of 49% at the absorption over 90% can be controlled in the varied temperature range from 150 to 400 K. Our results presents good candidates for potential devices operating from the radio to the THz range.
인동덩굴 추출물과 분획물의 항산화 활성 및 산화적 스트레스에 대한 세포 보호 효과
이예슬 ( Ye Seul Lee ),윤믿음 ( Mid Eum Yun ),이윤주 ( Yun Ju Lee ),박영민 ( Young Min Park ),이상래 ( Sang Lae Lee ),박수남 ( Soo Nam Park ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 한국미생물·생명공학회지 Vol.46 No.1
DPPH를 이용한 인동덩굴 추출물의 자유라디칼 소거활성(FSC50) 측정 결과, 인동덩굴 에틸아세테이트 분획물 (77.25μg/ml)이 50% 에탄올 추출물(152.00 μg/ml)보다 약 2배 높은 활성을 나타내었다. Luminol 발광법을 이용한 인동덩굴 추출물의 활성산소 소거활성(총 항산화능, OSC<sub>50</sub>) 측정 결과, 인동덩굴 에틸아세테이트 분획물(0.33 μg/ml) > 인동덩굴 50% 에탄올 추출물(1.12 μg/ml) > L-ascorbic acid (4.95μg/ml) 순서로 높게 나타났다. <sup>1</sup>O<sub>2</sub>으로 유도된 적혈구 파괴에 대한 세포 보호 효과(τ<sub>50</sub>) 측정 결과, 인동덩굴 추출물의 농도에 의존적으로 세포 보호 효과가 나타났으나, 고농도에서는 세포 보호 효과가 감소하는 경향을 나타내었다. 인동덩굴 50% 에탄올 추출물은 10 μg/ml의 농도(46.0 min)에서, 인동덩굴 에틸아세테이트 분획물은 1 μg/ml의 농도(52.3min)에서 가장 높은 세포 보호 효과를 나타내었다. 인동덩굴 추출물 및 분획물의 세포 독성 평가 결과, 본 실험에서는 0.4-12.5 μg/ml의 농도 범위를 설정하여 세포 보호 효과를 평가하였다. 과산화수소로 유도된 각질 형성 세포인 HaCaT세포 보호 효과는 인동덩굴 50% 에탄올 추출물 및 에틸아세테이트 분획물 12.5 μg/ml의 농도에서 각각 70.0, 78.6%의 세포 생존율을 나타냈으며, 대조군(65%)과 비교하여 유의한 세포 보호 효과를 가지고 있음을 확인하였다. UVB를 조사한 HaCaT 세포의 세포 내 ROS 소거 활성에서 인동덩굴 50% 에탄올 추출물 및 에틸아세테이트 분획물 모두 농도 의존적으로 ROS를 소거하였으며, 12.5 μg/ml 농도에서 각각 45.2, 63.3%의 ROS 소거율을 나타내었다. 이를 통해 인동덩굴 에틸아세테이트 분획물이 50% 에탄올 추출물보다 높은 세포 내 ROS 억제능이 있음을 확인하였다. TLC와 HPLC 크로마토그램을 이용한 인동덩굴의 에틸아세테이트 분획물의 성분 분석을 통해 caffeic acid, luteolin, apigenin, coumaric acid를 확인하였다. Caffeic acid와 luteolin의 뛰어난 환원력과 킬레이팅 작용이 인동덩굴 추출물의 활성산소 소거활성과 세포 보호 효과에 크게 기인했을 것으로 사료된다. 인동덩굴 50% 에탄올 추출물과 에틸아세테이트 분획물의 총 페놀성 화합물 및 총 플라보노이드 함량 측정 결과를 통해, 인동덩굴 에틸아세테이트 분획물이 50% 에탄올 추출물보다 많은 페놀성 화합물, 플라보노이드를 함유하고 있기 때문에 더욱 우수한 항산화 활성을 나타내었음을 확인하였다. 본 연구에서는 자외선에 의해 생성되는 다양한 ROS에 대한 인동덩굴 추출물 및 분획물의 항산화 활성을 평가하였고 이상의 결과를 통해 인동덩굴 추출물이 식물유래 천연 항산화제로서 가치가 있음을 시사하였다. 뿐만 아니라, 인동덩굴의 항산화 기능성 화장품 소재로서의 개발 가능성을 확인하였다. In this study, the antioxidant activities and cytoprotective effects against oxidative stress of Lonicera japonica Thunb. 50% ethanol extract and ethyl acetate fraction were investigated. Using the 1,1-diphenyl- 2-picrylhydrazyl assay, the free radical scavenging activity (FSC50) of L. japonica Thunb. 50% ethanol extract and ethyl acetate fraction was determined as 152.00 and 77.25 μg/ml, respectively. To measure the reactive oxygen species (ROS) scavenging activity, the total antioxidant capacity (OSC50) was determined by using a luminol-dependent chemiluminescence assay. The antioxidant activity of the ethyl acetate fraction (0.33 μg/ml) was approximately four times stronger than that of the 50% ethanol extract (1.12 μg/ml). The protective effect against <sup>1</sup>O<sub>2</sub>-induced cellular damage of human erythrocytes (τ<sub>50</sub>) was 46.0 min at 10 μg/ml of the 50% ethanol extract and 52.3 min at 1 μg/ml of the ethyl acetate fraction. We also investigated the cytoprotective effects against oxidative stress induced by H<sub>2</sub>O<sub>2</sub> and the intracellular ROS scavenging activity in response to UVB irradiation and found that the extract and fraction protected human skin cells from damage and reduced ROS. These results confirmed that L. japonica Thunb. was a valuable plant-derived natural antioxidant with potential for development as an antioxidative functional ingredient.
Ye-seul Kim,Yeon-soo Park,Gyeong-cheol Cho,Ki-ho Park,Shin-Hyang Kim,Seung Yeon Baik,Cho Long Kim,Soo-yun Jung,Won-Hye Lee,Youn-young Choi,Seung-Hwan Lee,Kee-Hong Choi 대한신경정신의학회 2018 PSYCHIATRY INVESTIGATION Vol.15 No.11
Objective This study evaluated the psychometric properties of the Korean Anxiety Screening Assessment (K-ANX) developed for screening anxiety disorders. Methods Data from 613 participants were analyzed. The K-ANX was evaluated for reliability using Cronbach’s alpha, item-total correlation, and test information curve, and for validity using focus group interviews, factor analysis, correlational analysis, and item characteristics based on item response theory (IRT). The diagnostic sensitivity and specificity of the K-ANX were compared with those of the Beck Anxiety Inventory (BAI) and Generalized Anxiety Disorder 7-item scale (GAD-7). Results The K-ANX showed excellent internal consistency (α=0.97) and item-total coefficients (0.92–0.97), and a one-factor structure was suggested. All items were highly correlated with the total scores of the BAI, GAD-7, and Penn State Worry Questionnaire. IRT analysis indicated the K-ANX was most informative as a screening tool for anxiety disorders at the range between 0.8 and 1.6 (i.e., top 21.2 to 5.5 percentiles). Higher sensitivity (0.795) and specificity (0.937) for identifying anxiety disorders were observed in the K-ANX compared to the BAI and GAD-7. Conclusion The K-ANX is a reliable and valid measure to screen anxiety disorders in a Korean sample, with greater sensitivity and specificity than current measures of anxiety symptoms.
( Ye Seul Lee ),( Yun Ju Lee ),( Soo Nam Park ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.11
Most people use cosmetics to protect their skin. Preservatives are often used to prevent their contamination upon use. There has been a great demand for natural preservatives due to recent reports on the side effects of parabens. Therefore, we evaluated the antimicrobial activities of Lonicera japonica and Magnolia obovata extracts and determined their potential as natural preservatives. We found that the 50% ethanol extract from L. japonica had antibacterial activity only against S. aureus and P. aeruginosa, while the ethyl acetate fraction showed antimicrobial activity against all six microbial strains tested. On the other hand, the 70% ethanol extract and the ethyl acetate fraction from M. obovata showed antimicrobial activity against all six strains. A synergistic effect against S. aureus, B. subtilis, and C. albicans was confirmed when two ethyl acetate fractions having antimicrobial activity against all six strains were used in combination. Synergistic activity against B. subtilis was also confirmed through kill-time analysis. Highperformance liquid chromatography was performed to identify the components of each extract. Based on the minimum inhibitory concentration and the results of a disc diffusion assay, we confirmed that caffeic acid and luteolin influenced the antimicrobial activity of L. japonica and that the antimicrobial activity of M. obovata was influenced by the interaction of magnolol and honokiol with other components. Therefore, this study suggests that the combination of L. japonica and M. obovata extracts may be used as a plant-derived natural preservative.