• Journal of Microbiology and Biotechnology
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• 제27권11호
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• pp.1932-1941
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• 2017

DFC-2, a methyl 5-[2-(dimethylamino)ethoxy]-7,12-dioxo-7,12-dihydrodinaphtho[1,2-b:2',3'-d]furan-6-carboxylate, is reported to have antitubercular effects against Mycobacterium tuberculosis. At concentrations ranging from 0.19 to $0.39{\mu}g/ml$, DFC-2 inhibited both drugusceptible and -resistant strains of M. tuberculosis. Microarray analyses were employed to gain insights into the molecular mechanisms of DFC-2's action in M. tuberculosis. The most affected functional gene category was "lipid biosynthesis," which is involved in mycolic acid synthesis. The decrease in transcription of genes related to mycolic acid synthesis was confirmed by RT-PCR. Furthermore, we found that DFC-2 triggered a reduction in mycolic acid levels, showing a similar pattern to that of mycolic acid synthesis inhibitor isoniazid. These results may explain how this compound kills mycobacteria efficiently by inhibiting mycolic acid synthesis.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.490-490
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• 2011

Graphene, hexagonal network of carbon atoms forming a one-atom thick planar sheet, has been emerged as a fascinating material for future nanoelectronics. Huge attention has been captured by its extraordinary electronic properties, such as bipolar conductance, half integer quantum Hall effect at room temperature, ballistic transport over ${\sim}0.4{\mu}m$ length and extremely high carrier mobility at room temperature. Several approaches have been developed to produce graphene, such as micromechanical cleavage of highly ordered pyrolytic graphite using adhesive tape, chemical reduction of exfoliated graphite oxide, epitaxial growth of graphene on SiC and single crystalline metal substrate, and chemical vapor deposition (CVD) synthesis. In particular, direct synthesis of graphene using metal catalytic substrate in CVD process provides a new way to large-scale production of graphene film for realization of graphene-based electronics. In this method, metal catalytic substrates including Ni and Cu have been used for CVD synthesis of graphene. There are two proposed mechanism of graphene synthesis: carbon diffusion and precipitation for graphene synthesized on Ni, and surface adsorption for graphene synthesized on Cu, namely, self-limiting growth mechanism, which can be divided by difference of carbon solubility of the metals. Here we present that large area, uniform, and layer controllable graphene synthesized on Cu catalytic substrate is achieved by acetylene-assisted CVD. The number of graphene layer can be simply controlled by adjusting acetylene injection time, verified by Raman spectroscopy. Structural features and full details of mechanism for the growth of layer controllable graphene on Cu were systematically explored by transmission electron microscopy, atomic force microscopy, and secondary ion mass spectroscopy.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.64-64
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• 2000

Since its discovery in 1991, the carbon nanotube has attracted much attention all over the world; and several method have been developed to synthesize carbon nanotubes. According to theoretical calculations, carbon nanotubes have many unique properties, such as high mechanical strength, capillary properties, and remarkable electronical conductivity, all of which suggest a wide range of potential applications in the future. Here we report the synthesis in the catalytic decomposition of acetylene at ~65 $0^{\circ}C$ over Ni deposited on SiO2, For the catalyst preparation, Ni was deposited to the thickness of 100-300A using effusion cell. Different approaches using porous materials and HF or NH3 treated samples have been tried for synthesis of carbon nanotubes. It is decisive step for synthesis of carbon nanotubes to form a round Ni particles. We show that the formation of round Ni particles by heat treatment without any pre-treatment such as chemical etching and observe the similar size of Ni particles and carbon nanotubes. Carbon nanotubes were synthesized by chemial vapour deposition ushin C2H2 gas for source material on Ni coated Si substrate. Ni film gaving 20~90nm thickness was changed into Ni particles with 30~90nm diameter. Heat treatment of Ni fim is a crucial role for the growth of carbon nanotube, High-resolution transmission electron microscopy images show that they are multi-walled nanotube. Raman spectrum shows its peak at 1349cm-1(D band) is much weaker than that at 1573cm-1(G band). We believe that carbon nanotubes contains much less defects. Long carbon nanotubes with length more than several $\mu$m and the carbon particles with round shape were obtained by CVD at ~$650^{\circ}C$ on the Ni droplets. SEM micrograph nanotubes was identified by SEM. Finally, we performed TEM anaylsis on the caron nanotubes to determine whether or not these film structures are truly caron nanotubes, as opposed to carbon fiber-like structures.

• 한국식품과학회지
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• 제51권1호
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• pp.58-63
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• 2019

본 연구에서 자소엽 조다당 추출물의 미백 활성을 평가하기 위하여 tyrosinase 억제활성과 melanocyte 세포에서 멜라닌 함량 및 멜라닌 관련 단백질 발현 억제능을 수행하였다. 자소엽 조다당 추출물은 tyrosinase 억제능을 관찰한 결과 자소엽 조다당 추출물의 농도가 증가할수록 활성이 유의적으로 증가하는 것으로 나타났다. 이러한 미백 효과가 melanoma 세포인 B16F10 세포 내에서도 일어나는지 확인하기 위하여 세포내 멜라닌 함량 및 tyrosinase 억제능을 살펴보았다. 자소엽 조다당 추출물은 B16F10 세포에 대하여 세포독성이 없는 농도에서 진행 하였으며, 세포내 멜라닌 함량 및 tyrosinase 활성 저해를 보여주었다. 이는 자소엽 조다당 추출물이 세포 내 MITF 발현을 억제시킴으로서 tyrosinase, TRP-1 및 TRP-2 단백질 발현을 억제함에 따라 미백효과를 확인하였다. 이러한 결과로 자소엽 조다당 추출물의 미백 활성을 확인 할 수 있었으며, 미백 산업 분야 및 식품의 기능성 소재로 이용한다면 천연 미백 소재로써 활용될 수 있을 것으로 판단된다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.468-470
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• 2004

CNT pastes with different inorganic binder such as glass frit and spin on glass (SOG) were synthesized by using multi-walled nanotube (MWNT) grown by CVD. The uniformity of cathode layer after firing was enhanced and the emission current density at an applied field of 7.95V/${\mu}m$ increased from 133${\mu}A$/$cm^2$ to 265${\mu}A$/$cm^2$ when inorganic binder changed from glass frit to SOG. The emission properties of CNT pastes with SOG were stable and uniform although firing was carried out at relatively high temperature of 450$^{\circ}C$ under air. It is concluded that SOG is more suitable inorganic binder than glass frit for field emission application.

• 한국미생물·생명공학회지
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• 제23권6호
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• pp.641-646
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• 1995

During the screening of inhibitors of melanin biosynthesis from microbial secondary metabolites, a fungal strain MR304 which was capable of producing high level of an inhibitor was selected. Based on taxonomic studies, this fungus could be classified as Trichoderma harzianum. The active compound (MR304-1) was purified from culture broth by Diaion HP-20 column chromatography, ethylacetate extraction, Sephadex LH-20 column chromatographv and HPLC. The inhibitor was identified as 3-(1,5-dihvdroxy-3-isocyanocyclopent-(E)-3-envl)prop-2-enoate by spectroscopic methods of UV, ESIMS, $^{1}$H-NMR, $^{13}$C-NMR, NOE, HMQC and HMBC. MR304-1 showed strong mushroom tyrosinase inhibitory activity with IC$_{50}$ value of 0.25 $\mu $g/ml. It inhibited melanin biosynthesis with 15 mm inhibition zone at 30 $\mu $g/paper disc in Streptomyces bikiniensis, a bacterium used as an indicator organism in this work. It also inhibited melanin biosynthesis in B16 melanoma cells with a niinimum inhibitory concentration of 0.05 $\mu $g/ml.

• 한국세라믹학회지
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• 제47권2호
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• pp.183-188
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• 2010

$Ce_{0.8}Gd_{0.2}O_{1.9}$(GDC20) powder was synthesized by milling of $CeO_2$ slurry and Gd oxalate precipitation. The mixture of $CeO_2$ powder and Gd precipitates calcined at $600^{\circ}C$ for 2 h showed the particle size distribution similar to that of $CeO_2$ powder, which had been milled during the synthesis process. Attrition milling of the calcined powder with an average particle size of $0.36\;{\mu}m$ for 2 h resulted in a decrease in the particle size to $0.24\;{\mu}m$. Although the milled powder consisted of small particles(<$1\;{\mu}m$), a small amount of fine platy $Gd_2O_3$ particles, which had been survived in the milling process, was observed. Sintering of the powder compacts for 4 h showed relative densities of 80.7% at $1300^{\circ}C$ and 97% at $1400^{\circ}C$, respectively. Densification was found to almost complete at $1500^{\circ}C$, resulting in a dense and homogeneous microstructure with a relative density of 99.5%.

• KSBB Journal
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• 제32권3호
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• pp.187-192
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• 2017

In this study, we investigated the effect of Rumex axetosella, Sonchus oleraceus and Euphoibia jolkini extracts on tyrosinase activity and melanin production as natural products of whitening functional cosmetics. To measure the melanin production, 50, 100, $200{\mu}g/mL$ of Rumex axetosella, Sonchus oleraceus and Euphoibia jolkini extracts were treated on ${\alpha}-MSH$ treated B16F10 melanoma cells, respectively. Melanin contents in ${\alpha}-MSH$ treated B16F10 melanoma cells were decreased by 41.5, 51.11, and 61% in $200{\mu}g/mL$ treatment compared to none treatment, respectively. In addition, the intracellular tyrosinase activity was decreased after treatments with all extracts. Furthermore, $100{\mu}g/mL$ of Euphoibia jolkini extract was decreased 81.5% of melanin production in B16F10 melanoma cells. When the three extracts were compared, Euphoibia jolkini extract was considered to be the most functional material for whitening effect.

• Biomolecules & Therapeutics
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• 제9권3호
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• pp.183-187
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• 2001

Nitric oxide (NO) produced in large amounts by the inducible nitric oxide synthase (iNOS) is known to be responsible for the vasodilation and hypotension observed in septic shock and inflammation. The inhibitors of iNOS, thus, may be useful candidate for the treatment of inflammatory diseases accompanied by the overproduction of NO. We prepared alcoholic extracts of Chinese medicinal plants and screened their inhibitory activity against NO production in lipopolysaccharide (LPS)-activated macrophages. Among the 80 kinds of extracts of herbal drugs, 15 extracts showed potent inhibitory activity of NO production above 80% at the concentration o$50\mu\textrm{g}/ml$. These potent extracts showed dose dependent inhibition of NO production of LPS-activated macrophages at the concentration of 50, 30,$10\mu\textrm{g}/ml$. Especially, Rhus chinensis, Senecio scandens and Wikstroemia indica showed most potent inhibition above 50% at the concentration of $10\mu\textrm{g}/ml$. These plants are promising candidates for the study of the activity-guided purification of active compounds and would be useful for the treatment of inflammatory diseases and endotoxemia accompanying the overproduction of NO.

• Clinical and Experimental Reproductive Medicine
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• 제24권1호
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• pp.35-42
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• 1997

The present study was designed to define the role of prostaglandin in the development and hatching of mouse embryo. The effects of indomethacin, an inhibitor of prostaglandin synthesis, on the development and hatching of morula and blastocyst were examined. In early morula stage, embryos were degenerated significantly at 100 ${\mu}M$ and 200 ${\mu}M$ indomethacin. However, the viability of embryos was not influenced by concentration in any other embryonic stages. In all embryonic stages, the hatching was suppressed with concentration dependent manner, but expansion was not suppressed. Particularly, in 84h embryos post hCG injection, the hatching was suppressed significantly compared with post hCG 72h or 96h embryos. When embryos were treated with 100 ${\mu}M$ indomethacin for a specific time (12h) in according to the development stage, the hatching was suppressed all groups. These suppressional effect was decreased as embryonic development stage was progressed. However, the expansion was not affected in all treatment group. This study suggests that hatching-related metabolic substances are synthesized from morula stage and intraembryonic signaling mediated prostaglandin was important for development and hatching of mouse embryo.