• Proceedings of the Korean Society of Applied Pharmacology
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• 2001.11a
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• pp.106-106
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• 2001

Matrix metalloproteases (MMPs) 는 다양한 세포에서 전이와 침윤성에 중요한 역할을 한다. MMP의 내인성 저해제인 tissue inhibitor of motalloprotease-2 (TIMP-2) 는 MMP-2에 높은 특이성을 지닌다. MMP-2와 TIMP-2사이의 불균형은 침윤성과 전이와 같은 병리학적 과정과 관계되는 extracellular matrix (ECM)의 퇴화를 일으킨다. TIMPs는 분비되는 분자이기 때문에 특정한 암의 유전자 치료에 사용될 가능성을 지닌다. 본 연구에서는 MMP-2가 H-ras에 의해 유도된 침윤성에 책임지는 것으로 보여지는 H-ras MCF10A 세포에 TIMP-2 유전자를 함유하는 retrovirus를 이용하여 연구하였다. TIMP-2 유전자를 함유하는 재조합 retrovirus는 PG13 세포를 infection 시키는데 사용되었다. H-ras MCF10A 세포는 PGl3 세포의 conditioned media로 처리되었을 때, gelatin zymography에서 MMP-2의 분비가 농도의존적으로 저해되었다. 또한 retrovirus에 의한 TIMP-2의 과잉 발현은 농도의존적으로 H-ras MCF10A 세포의 침윤성과 이동성을 상당히 감소시킨다. 이와 같은 실험 결과는 TIMP-2가 H-ras MCF10A 세포에서 MMP-2 분비와 세포의 침윤성, 이동성을 감소시키는 역할을 지닌다는 것과 TIMP-2 유전자를 함유하는 retrovirus가 효과적으로 MMP-2 분비, 세포 침윤성, 세포 이동성을 감소시켰다는 것을 보여 준다. 이는 암의 예방과 치료를 위한 유전자 치료법의 적용에 상당한 가능성을 제시한다.

• Korean Journal of Metals and Materials
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• v.50 no.3
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• pp.218-223
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• 2012

Fe-(8.5, 18.5, 28.3, 36.9) wt% Cr alloys were corroded between 600 and $800^{\circ}C$ for up to 70 h in a 1 atm gas mixture that consisted of 0.0242 atm of $H_2S$, 0.031 atm of water vapor, and 0.9448 atm of nitrogen gas. Their corrosion resistance increased with an increment in the Cr content. The Fe-8.5%Cr alloy corroded fast, forming thick, fragile, nonadherent scales that consisted primarily of an outer FeS layer and an inner (Fe, Cr, O, S)-mixed layer. The outer FeS layer grew into the air by the outward diffusion of $Fe^{2+}$ ions, whereas the inner mixed layer grew by the inward diffusion of oxygen and sulfur ions. At the interface of the outer and inner scales, voids developed and cracking occurred. The Fe-(18.5, 28.3, 36.9)% Cr alloys displayed much better corrosion resistance than the Fe-8.5Cr alloy, because thin $Cr_2O_3$ or $Cr_2S_3$ scales formed.

• Korean Chemical Engineering Research
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• v.51 no.3
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• pp.297-302
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• 2013

Enhancement of photocatalytic activity of UV/photocatalysis was carried out to oxidize the gaseous $H_2S$ in a tubular reactor coated with photocatalyst of sol type $TiO_2$. EtOH was used as the standard material to select the photocatalyst, and it was confirmed that the reactor activity was dependent on the coated surface characteristics. The selected photocatalytic reactor, which coated with STS-01, showed about 80% conversion when the gas linear velocity was 0.01 m/s and relative humidity was 40%. However, the conversion level of the reaction decreased significantly with increasing gas linear velocity. Pt was loaded on the photocatalyst to enhance and maintain the performance of the reactor, which enhanced the conversion level of $H_2S$ more than 95% under the same experimental condition.

• Korean Journal of Materials Research
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• v.33 no.5
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• pp.189-194
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• 2023

This study uses first-principles calculations to investigate the mechanical properties and effect of strain on the electronic properties of the 2D material 1H-PbX₂ (X: S, Se). Firstly, the stability of the 1H Pb-dichalcogenide structures was evaluated using Born's criteria. The obtained results show that the 1H-PbS₂ material possesses the greatest ideal strength of 3.48 N/m, with 3.68 N/m for 1H-PbSe₂ in biaxial strain. In addition, 1H-PbS₂ and 1H-PbSe₂ are direct semiconductors at equilibrium with band gaps of 2.30 eV and 1.90 eV, respectively. The band gap was investigated and remained almost unchanged under the strain ε_xx but altered significantly at strains ε_yy and ε_bia. At the fracture strain in the biaxial direction (19 %), the band gap of 1H-PbS₂ decreases about 60 %, and that of 1H-PbSe₂ decreases about 50 %. 1H-PbS₂ and 1H-PbSe₂ can convert from direct to indirect semiconductor under the strain ε_yy. Our findings reveal that the two structures have significant potential for application in nanoelectronic devices.

• Bulletin of the Korean Chemical Society
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• v.18 no.3
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• pp.311-316
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• 1997

The synthesis and characterization of the mononuclear group 13 heterocyclic carboxaldehyde methyldithiocarbazate complexes Me2M[NC5H4CRNNC(S)SCH3] (M=Al, R=H(1); M=Ga, R=H(2); M=Al, R=CH3(3); M-Ga, R=CH3(4); M=In, R=CH3(5)) are described. Compounds 1-5 were prepared by the reaction of MMe3 (M=Al, Ga, In) with 2-formy or 2-acetylpyridine-S-methyldithiocarbazate in toluene. These compounds 1-5 have been characterized by microanalysis, NMR (1H, 13C) spectroscopy, mass spectra, and single-crystal X-ray diffraction. X-ray single-crystal diffraction analyses reveal that 4-5 are mononuclear metal compounds with coordination number of 5 and N,N,S coordination mode.

• 한국전기화학회:학술대회논문집
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• 2005.07a
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• pp.169-172
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• 2005

• Journal of the Chungcheong Mathematical Society
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• v.13 no.2
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• pp.87-98
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• 2001

In this paper, we study hash function, which will take a message of arbitrary length and produce a massage digest of a specified size. The message digest will then be signed. We have to be careful that the use of a hash function h does not weaken the security of the signature scheme, for it is the message digest that is signed, not the message. It will be necessary for h to satisfy certain properties in order to prevent various forgeries. In order to prevent various type of attack, we require that hash function satisfy collision-free property. In section 1, we introduce some definitions and collision-free properties of hash function. In section 2, we study a discrete log hash function and introduce the main theorem as follows : Theorem Suppose $h:X{\rightarrow}Z$ is a hash function. For any $z{\in}Z$, let $$h^{-1}(z)={\lbrace}x:h(x)=z{\rbrace}$$ and denote $s_z={\mid}h^{-1}(z){\mid}$. Define $$N={\mid}{\lbrace}{\lbrace}x_1,x_2{\rbrace}:h(x_1)=h(x_2){\rbrace}{\mid}$$. Then (1) $\sum\limits_{z{\in}Z}s_z={\mid}x{\mid}$ and the mean of the $s_z$'s is $\bar{s}=\frac{{\mid}X{\mid}}{{\mid}Z{\mid}}$ (2) $N=\sum\limits_{z{\in}Z}{\small{s_z}}C_2=\frac{1}{2}\sum\limits_{z{\in}Z}S_z{^2}-\frac{{\mid}X{\mid}}{2}$. (2) $\sum\limits_{z{\in}Z}(S_z-\bar{s})^2=2N+{\mid}X{\mid}-\frac{{\mid}X{\mid}^2}{{\mid}Z{\mid}}$.

• Korean Journal of Optics and Photonics
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• v.3 no.2
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• pp.111-116
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• 1992

ZnS:Sm, F TFEL devices with double insulating layer are prepared by e-beam evaporation method. Electroluminescence and luminous efficiency of the device fabricated at various conditions are investigated. The main transitions on the emission spectra for ZnS:Sm, F TFEL device occur at$^4G_{5/2}\to^6H_{9/2}^4G_{5/2}\to^6H_{7/2}, \;^4G_{5/2}\to^6H_{5/2}\to$.Among them, the dominant spectral line and its corresponding transition occur at $^4G_{5/2}\to^6H_{9/2}$(650 nm) and results in an orange-red emission color. The optimum concentration and substrate temperature for the ZnS:Sm, F TFEL device are around 1 wt% and $200^{\circ}C$. Luminous efficiency for the device is the largest at optimum condition.

• Journal of the Korean institute of surface engineering
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• v.49 no.4
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• pp.339-343
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• 2016

ASTM T23 steel with a composition of Fe-2.25%Cr-1.6%W corroded at 600 and $700^{\circ}C$ for 5-70 h in $N_2$/(0.5, 2.5)%$H_2S$-mixed gas at 1 atm. It corroded rapidly, forming the outer FeS scale and the inner (FeS, $FeCr_2O_4$)-mixed scale. The ensuing outward diffusion of $Fe^{2+}$ ions during corrosion led to the protrusion of FeS platelets over the outer FeS scale. The formation of FeS at the surface facilitated the oxidation of Cr to $FeCr_2O_4$ in the inner scale. Since the nonprotective FeS scale existed over the whole scale, T23 steel displayed poor corrosion resistance in the $H_2S$-containing atmosphere.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.1
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• pp.77-85
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• 2004

In this study, the concentrations of reduced S compounds (including hydrogen sulfide (H$_2$S); methyl mercaptan ($CH_3$SH); dimethyl sulfide (($CH_3$)$_2$S); carbon disulfide (CS$_2$); and dimethyl disulfide (($CH_3$)$_2$S$_2$) were determined from landfill gas (LFG) in three municipal landfill sites in the two cities of Gwang Ju (GJ) and Jeju (JJ), Korea. The S gas concentrations measured in these landfill sites were found to be dominated by H$_2$S with its mean concentration of 850 ppm from 10 LFG samples. Both absolute and relative dominance of H$_2$S was seen to be significant in most LFG samples, except those collected from very old and inactive landfills. Unlike the pattern of H$_2$S, other S gases were typically observed at much reduced concentration levels (a few ppm or less) as follows: DMS (3.5); $CH_3$SH (1.3); CS$_2$(1.2); and DMDS (0.02 ppm). If compared equally in mass concentration unit (mg m$^{-3}$ ), H$_2$S generally explained far above 90% of all S gas masses determined concurrently. Moreover, as its mass concentration commonly exceeds those of the major aromatic VOC components in LFG (like benzene and toluene), it appeared to be one of the most dominant gaseous components emitted as LFG in a quantitative sense.