• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.172-172
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• 2010

In the area of optoelectronic devices based on GaN and related ternary compounds, the two-dimensional system like as quantum wells (QWs) has been investigated as an effective structure for improving the light-emitting efficiency. Generally, the quantum well active regions in III-nitride light-emitting diodes grown on conventional c-plane sapphire substrates have critical problems given by the quantum confined Stark effect (QCSE) due to the effects of strong piezoelectric and spontaneous polarizations. However, the QWs grown on nonpolar templates are free from the QCSE since the polar-axis lies within the growth plane of the template. Also the unique characteristic of linear polarized light emission from nonpolar QW structures is attracting attentions because it is proper to the application of back-light units of liquid crystal display. In this study, we characterized optical properties of the a-plane InGaN/GaN QW structures by temperature-dependent photoluminescence (TDPL) measurements. From the photoluminescence (PL) spectrum measured at 300 K, green emission centered at 520 nm was observed for the QW region. Since indium incorporation on nonpolar QWs is lower than that on c-plane, this high indium-doping on a-plane InGaN QWs is not common. Therefore, the effect of high indium composition on optical properties in a-plane InGaN QWs will be extensively studied.

• Archives of Pharmacal Research
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• 제28권12호
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• pp.1365-1375
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• 2005

The antiestrogenic effects of marijuana smoke condensate (MSC) and three major cannabinoids, i.e., $\bigtriangleup^{9}$-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN), were evaluated using in vitro bioassays, viz., the human breast cancer cell proliferation assay, the recombinant human estrogen receptor (ER) competitive binding assay, and the reporter gene assay. The inhibitory effects on estrogen were also examined using the ethoxyresorufin-O­deethylase (EROD) assay, the aromatase assay, and the 17$\beta$-estradiol ($E_{2}$) metabolism assay. The results showed that MSC induced the antiestrogenic effect via the ER-mediated pathway, while THC, CBD, and CBN did not have any antiestrogenic activity. This suggests that the combined effects of the marijuana smoke components are responsible for the antiestrogenicity of marijuana use. In addition, MSC induced the CYP1A activity and the $E_{2}$ metabolism, but inhibited the aromatase activity, suggesting that the antiestrogenic activity of MSC is also related to the indirect ER-dependent pathway, as a result of the depletion of the in situ $E_{2}$ level available to bind to the ER. In conclusion, pyrogenic products including polycyclic aromatic hydrocarbons (PAHs) in the non-polar fraction, which is the most biologically active fraction among the seven fractions of MSC, might be responsible for the antiestrogenic effect.

• Natural Product Sciences
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• 제26권4호
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• pp.340-344
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• 2020

A new chromone analogue (1) was isolated from an EtOAc-extract of Pleosporales sp. culture medium, together with five known chromones (2 - 6). The isolation workflow was guided by a Molecular Networking-based dereplication strategy. The chemical structure of the new compound was elucidated using NMR and MS spectroscopy, and the absolute configuration was established by the Mosher's method. All isolated compounds were evaluated for their inhibitory effects on lipopolysaccharide-induced nitirc oxide production in RAW 264.7 macrophages. Compound 1 showed marginal inhibitory activity with an IC50 value of 118.7 μM.

• Ocean and Polar Research
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• 제45권3호
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• pp.113-123
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• 2023

Humic substances are refractory organic compounds that are relatively low in biological activity but known to stimulate phytoplankton growth in estuarine and marine environments. The effect of humic substances on phytoplankton growth was investigated in the seawater zone of the Yeongsan River estuary where an episodic anthropogenic freshwater is discharged, affecting its water properties directly. Water samples and data of water properties were collected at three stations (Sts. A-C) along the channel of the seawater zone in February, May, August and November, 2009. The collected water samples were incubated after humic acids (HA) were added in mesocosm experiments. Phytoplankton (chlorophyll-a) were fractionated into net- (> 20 ㎛) and nano-size (< 20 ㎛) to examine the response of phytoplankton according to size. Their response to HA treatment was assessed by repeated measures analysis of variance (RM-ANOVA). The experiments showed that phytoplankton biomass (chlorophyll-a) significantly increased after HA were added at the stations near the sea dike. Especially, nano-sized chlorophyll-a concentrations increased significantly throughout the seasons. This indicates that understanding the behavior of refractory organic matters such as humic substances is required to better manage altered estuarine ecosystems including the Yeongsan River estuary which are affected by episodic discharge of freshwater from sea dikes.

• Nutrition Research and Practice
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• 제8권3호
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• pp.257-266
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• 2014

BACKGROUND/OBJECTIVE: Licorice has been shown to possess cancer chemopreventive effects. However, glycyrrhizin, a major component in licorice, was found to interfere with steroid metabolism and cause edema and hypertension. The roasting process of licorice modifies the chemical composition and converts glycyrrhizin to glycyrrhetinic acid. The purpose of this study was to examine the anti-carcinogenic effects of the ethanol extract of roasted licorice (EERL) and to identify the active compound in EERL. MATERIALS/METHODS: Ethanol and aqueous extracts of roasted and un-roasted licorice were prepared. The active fraction was separated from the methylene chloride (MC)-soluble fraction of EERL and the structure of the purified compound was determined by nuclear magnetic resonance spectroscopy. The anti-carcinogenic effects of licorice extracts and licochalcone A was evaluated using a MTT assay, Western blot, flow cytometry, and two-stage skin carcinogenesis model. RESULTS: EERL was determined to be more potent and efficacious than the ethanol extract of un-roasted licorice in inhibiting the growth of DU145 and MLL prostate cancer cells, as well as HT-29 colon cancer cells. The aqueous extracts of un-roasted and roasted licorice showed minimal effects on cell growth. EERL potently inhibited growth of MCF-7 and MDA-MB-231 breast, B16-F10 melanoma, and A375 and A2058 skin cancer cells, whereas EERL slightly stimulated the growth of normal IEC-6 intestinal epithelial cells and CCD118SK fibroblasts. The MC-soluble fraction was more efficacious than EERL in inhibiting DU145 cell growth. Licochalcone A was isolated from the MC fraction and identified as the active compound of EERL. Both EERL and licochalcone A induced apoptosis of DU145 cells. EERL potently inhibited chemically-induced skin papilloma formation in mice. CONCLUSIONS: Non-polar compounds in EERL exert potent anti-carcinogenic effects, and that roasted rather than un-roasted licorice should be favored as a cancer preventive agent, whether being used as an additive to food or medicine preparations.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.327.1-327.1
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• 2014

Nitrides-on-silicon structures are considered to be an excellent candidate for unique design architectures and creating devices for high-power applications. Therefore, a lot of effort has been concentrating on growing high-quality III-nitrides on Si substrates, mostly Si(111) and Si(001) substrates. However, there are several fundamental problems in the growth of nitride compound semiconductors on silicon. First, the large difference in lattice constants and thermal expansion coefficients will lead to misfit dislocation and stress in the epitaxial films. Second, the growth of polar compounds on a non-polar substrate can lead to antiphase domains or other defective structures. Even though the lattice mismatches are reached to 16.9 % to GaN and 19 % to AlN and a number of dislocations are originated, Si(111) has been selected as the substrate for the epitaxial growth of nitrides because it is always favored due to its three-fold symmetry at the surface, which gives a good rotational matching for the six-fold symmetry of the wurtzite structure of nitrides. Also, Si(001) has been used for the growth of nitrides due to a possible integration of nitride devices with silicon technology despite a four-fold symmetry and a surface reconstruction. Moreover, Si(110), one of surface orientations used in the silicon technology, begins to attract attention as a substrate for the epitaxial growth of nitrides due to an interesting interface structure. In this system, the close lattice match along the [-1100]AlN/[001]Si direction promotes the faster growth along a particular crystal orientation. However, there are insufficient until now on the studies for the growth of nitride compound semiconductors on Si(110) substrate from a microstructural point of view. In this work, the microstructural properties of nitride thin layers grown on Si(110) have been characterized using various TEM techniques. The main purpose of this study was to understand the atomic structure and the strain behavior of III-nitrides grown on Si(110) substrate by molecular beam epitaxy (MBE). Insight gained at the microscopic level regarding how thin layer grows at the interface is essential for the growth of high quality thin films for various applications.

• 한국자원식물학회지
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• 제29권1호
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• pp.39-45
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• 2016

2012년부터 2013년에 걸쳐 식물체 근권과 비근권 토양을 수집하였다. 수집한 토양을 희석평판법을 이용하여 총 782개의 세균을 분리하였고, 분리한 세균을 실험실내에서 Trichothecium roseum과의 대치배양을 통해 균사생장억제율이 80% 내외로 우수한 길항력을 나타내는 균주를 선발하였다. I-plate에서 HK2균주와 T. roseum두 균을 격리하여 밀폐배양 시 모두 균사생장억제 효과는 없기 때문에 휘발 물질은 아닌 것으로 판단되었다. NB배지에 길항균주와 T. roseum을 액체배양 한 결과 88% 이상 균사생장억제 효과를 보였다. HK2균주를 동정하기 위해 16S rDNA 염기서열분석과 API 50 CHB Kit (BioMerieux, France)를 이용하여 생화학적 특성을 분석한 결과 Bacillus subtilis로 동정되었다. HK2 균주가 생산한 항진균물질을 butanol로 추출한 후 flash column chromatography를 이용하여 항진균물질을 정제한 결과 methanol 80%의 조건에서 잘 분리되었으며 향후 분리 순화를 통한 화학구조분석이 필요하다.

• 한국식품영양과학회지
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• 제18권3호
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• pp.247-254
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• 1989

튀김 식품에 사용되는 기름들은 반복적으로 높은 온도에서 계속하여 사용되므로 튀김기름이 산패 중합되어서 인체에 해를 끼칠 수가 있다. 그러나 현재 사용하던 기름에 대한 폐기처분이나 어떤 법적인 규제가 없다. 이 연구보고서는 일반시장에서 반복하여 사용된 기름에 새 기름을 첨가하여 사용한 기름과 가정용 기름을 시료로 하여 유지의 일반성 상과 가열시간에 따르는 유지의 변화를 조사하여 다음과 같은 결과를 얻었다. 일반시장에서 몇가지 튀김식품에 사용되는 기름은 가정용 튀김기름보다 그 품질면에서 열등하였다. 또한 가열하기전 신선한 기름 그 자체가 정제식용유의 규격기준에 미달되었다. 튀김기름은 튀김횟수가 증가하고 가열시간이 증가함에따라 유리지방산가, 과산화물가와 요오드가의 증가 또는 감소등으로 유지 산패의 전형적인 특징을 나타내다가 신선한 기름의 첨가로 가열전 기름의 수준으로 환원되어졌다. 튀김기름속에 잔존하는 비휘발성 극성성분의 함량은 가열시간이 증가함에 따라 신선한 기름의 첨가에 관계없이 증가하였으며 가열 22시간 후에는 극성성분의 함량이 산패된 기름의 수준까지 이르렀다. 튀김기름의 지방산 조성은 가열시간이 경과함에 따라 팔미친산, 스테아린산 함량의 비율은 증가하였고 리놀레인산, 리놀레닌산은 그 함량이 각각 감소하였다. 채종유중 고에루신산 채종유는 다량의 에루신산을 함유하고 있으므로 식용에 부적합하다고 할 수 있다.

• 한국식품과학회지
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• 제24권2호
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• pp.171-176
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• 1992

더덕(Codonopsis lanceolata)의 휘발성 향기성분을 분석하기 위해 gas co-distillation(GCD), solvent extraction/fractionation(SLF), headspace sampling(HSS) 방법을 사용하여 향기성분을 분리농축하고 분석 비교한 결과 SEF와 HSS 방법으로 얻은 농축물들의 향이 원래의 더덕향과 가장 유사했으며 gas chromatogram들의 양상도 비슷했으나 peak들의 크기에 있어서 차이를 보였다. SEF 농축물에서는 달콤한 향을 기리고 HSS 농축물에서는 풋내를 비교적 강하게 느낄 수 있었으나 GCD 농축물의 경우 일정 증류시간이 지나면 한악취를 느낄 수 있었다. SEF와 HSS 방법은 GCD에 비해서 적은 조작 단계로 손쉽게 빠른 시간내에 분리 농축이 가능했다. 농축한 향기성분은 GC-MS와 극성이 다른 두 column을 사용한 GC-RI system을 이용하여 확인하였다. 특히 GC-RI는 isomer의 확인에 효과적이었으며 극성 FFAP column은 극성 화합물의 확인에 보다 적합했다. 35가지의 향기성분들을 동정하였는데 그중 24개의 성분들은 simultaneous distillation extraction 농축물에서는$^{(5)}$ 확인되지 않았던 향기성분들이다. 화인된 성분들중 trans-2-hexenal, cis-3-hexen-1-ol, trans-2-hexen-1-ol, hexanol은 더덕의 풋내를, 1-octen-3-ol은 신선한 풍미를 그리고 amyl propionate를 비롯한 다수의 에스터 화합물 등은 더덕 특유의 달콤한 향에 복합적으로 작용할 것으로 추정된다.

• Applied Biological Chemistry
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• 제32권4호
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• pp.393-400
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• 1989

토양 중에서 3개월과 6개월간 $^{14}C-bentazon$을 숙성시키는 동안 방출된 $^{14}CO_2$의 량은 처리 방사능의 각각 6.1과 14.8%이었다. 토양중의 지렁이는 벼의 뿌리에 의한 $^{14}C-bentazon$의 흡수를 증가시켰다. 토양중의 $^{14}C-bentazon$으로부터 방출되는 $^{14}CO_2$량은 벼를 재배하거나 지렁이가 존재할 때 증가하였다. 벼에 의한 $^{14}C-bentazon$ 잔류물의 흡수는 토양중 지렁이의 유무에 관계없이 숙성기간이 증가함에 따라 현저히 감소하였다. 벼의 경우에는 옥수수를 이용한 연구와 비교해 볼 때 $^{14}C-$표지화합물의 훨씬 많은 량이 지상부로 이행되었다. 추출 불가능한 흡착잔류물의 량은 3개월까지는 숙성기간이 증가할수록 현저히 증가하였다. 토양으로부터 추출된 화합물의 극성은 숙성기간과 벼의 생육에 따라 증가하였으며 이는 극성 대사 산물의 형성을 시사해 준다.