• Journal of Life Science
• /
• v.21 no.11
• /
• pp.1558-1564
• /
• 2011

Cytochrome P450 2J2 (CYP2J2) plays important roles in the metabolism of endogenous metabolites such as arachidonic acid as well as therapeutic drugs. CYP2J2 is overexpressed in human cancer tissues and cancer cell lines, as well as in epoxyeicosatrienoic acids (EETs) and CYP2J2-mediated metabolites, and prevent apoptosis of cancer cells. This study aimed to screen marketed drugs for inhibitory potential on CYP2J2 isoforms using human liver microsomes. The initial screen isolated 4 compounds, from 120 marketed drugs, that inhibited the CYP2J2-mediated astemizole O-demethylation more than 50% in the following the order: haloperidol (75%) > terfenadine (56%) > aripiprazole (55%) > miconazole (52%). Miconazole strongly inhibited CYP2J2-mediated ebastine hydroxylation ($IC_{50}$=11.2 ${\mu}M$) and terfenadine hydroxylation ($IC_{50}$=2.2 ${\mu}M$), and terfenadine also inhibited CYP2J2-mediated ebastine hydroxylation ($IC_{50}$=13.6 ${\mu}M$) in a dose dependent manner. The present data suggest that these drugs are potential candidates for further evaluation for their anti-cancer activities.

• Journal of Life Science
• /
• v.21 no.3
• /
• pp.444-450
• /
• 2011

Perchlorate ($ClO_4^-$) is a contaminant found in surface water and soil/ground water. Autotrophic perchlorate-reducing bacteria (PRB) use hydrogen gas ($H_2$) as an electron donor to remove perchlorate. Since iron corrosion can produce $H_2$, feasibility of autotrophic perchlorate-removal using zero-valent iron (ZVI) was examined in this study using activated sludge that is easily available from a wastewater treatment plant. Batch test showed that activated sludge microorganisms could successfully degrade perchlorate in the presence of ZVI. The perchlorate biodegradation was confirmed by molar yield of $Cl^-$ as perchlorate was degraded. Scanning electron microscope revealed that rod-shaped microorganisms on the surface of iron particles used for the autotrophic perchlorate-removal, suggesting that iron particles could serve as supporting media for the formation of biofilm as well. DGGE analyses revealed that microbial profile of the inoculum (activated sludge) was different from that of biofilm sample obtained from the ZVI-added enrichment culture used for $ClO_4^-$-degradation. A major band of the biofilm sample was most closely related to the class Clostridia.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2012.05a
• /
• pp.84-84
• /
• 2012

소자가 고집적화 됨에 따라, 비저항이 낮고 electro migration (EM), Stress Migration (SM) 특성이 우수한 구리(Cu)를 배선재료로서 사용하고 있다. 그러나, 구리는 Si과 $SiO_2$의 내부로 확산이 빠르게 일어나, Si 소자 내부에 deep donor level을 형성하고, 누설 전류를 증가시키는 등 소자의 성능을 저하시킬 수 있는 문제점을 가지고 있다. 그러나, electroplating 을 이용하여 증착한 Cu 박막은 일반적으로 확산 방지막으로 쓰이는 TiN, TaN, 등의 물질과의 접착 (adhesion) 특성이 나쁘다. 따라서, Cu CMP 에서 증착된 Cu 박막의 벗겨지거나(peeling), EM or SM 저항성 저하 등의 배선에서의 reliability 문제를 야기하게된다. 따라서 Cu 와 접착 특성이 좋은 새로운 확산방지막 또는 adhesion layer의 필요성이 대두되고 있다. 본 연구에서는 이러한 Cu 배선에서의 접착성 문제를 해결하고자 Metal organic chemical vapor deposition (MOCVD)을 이용하여 제조한 코발트(Co) 박막을 $Cu/TaN_x$ 사이의 접착력 개선을 위한 adhesion layer로 적용하려는 시도를 하였다. Co는 비저항이 낮고, Cu 와 adhesion이 좋으며, Cu direct electroplating 이 가능하다는 장점을 가지고 있다. 하지만, 수소 분위기에서 $C_{12}H_{10}O_6(Co)_2$ (dicobalt hexacarbonyl tert-butylacetylene, CCTBA) 전구체에 의한 MOCVD Co 박막의 경우 탄소, 산소와 같은 불순물이 다량 함유되어 있어, 비저항, surface roughness 가 높아지게 된다. 따라서 구리 전착 초기에 구리의 핵 생성(nucleation)을 저해하고 핵 생성 후에도 응집(agglomeration)이 발생하여 연속적이고 얇은 구리막 형성을 방해한다. 이를 해결하기 위해, MOCVD Co 박막 증착 시 수소 반응 가스에 암모니아를 추가로 주입하여, 수소/암모니아의 분압을 1:1, 1:6, 1:10으로 변화시켜 $Co/TaN_x$ 박막의 특성을 비교 분석하였다. 각각의 수소/암모니아 분압에 따른 $Co/TaN_x$ 박막을 TEM (Transmission electron microscopy), XRD (X-ray diffraction), AES (Auger electron spectroscopy)를 통해 물성 및 조성을 분석하였고, AFM (Atomic force microscopy)를 이용하여, surface roughness를 측정하였다. 실험 결과, $Co/TaN_x$ 박막은 수소/암모니아 분압 1:6에서 90 ${\mu}{\Omega}-cm$의 낮은 비저항과 0.97 nm 의 낮은 surface roughness 를 가졌다. 뿐만 아니라, MOCVD 에 의해 증착된 Co 박막이4-6 % concentration 의 탄소 및 산소 함량을 가지는 것으로 나타났고, 24nm 크기의 trench 기판 위에 약 6nm의 $Co/TaN_x$ 박막이 매우 균일하게 형성된 것을 확인 할 수 있었다. 이러한 결과들은, 향후 $Co/TaN_x$ 박막이 Cu direct electroplating 공정이 가능한 diffusion barrier로서 성공적으로 사용될 수 있음을 보여준다.

• Journal of the Korean Chemical Society
• /
• v.37 no.8
• /
• pp.765-772
• /
• 1993

Two-dimensional potassium tetratitanate ($K_2Ti_4O_9$) and three-dimensional potassium hexatitanate ($K_2Ti_6O_{13}$) fibers have been prepared by the combined method consisting of the flux melting (1150$^{\circ}C$)-slow cooling (cooling rate = 5$^{\circ}C$/h) process from the starting raw materials of $K_2CO_3$, and $TiO_2$ with the flux of $K_2MoO_4$. It was found that the fiber growth reaction is strongly dependent upon the mole ratio of flux (F) to raw material (R), which is 7 : 3 (F : R) as for the optimum growth condition. Relatively long fibers (average length ${\thickapprox}$ 4 mm) with a mixture of $K_2Ti_4O_9$ (major) and $K_2Ti_6O_{13}$ (minor) could be obtained when the reaction was carried out for the $K_2MoO_4-$K_2O{\cdot}4TiO_2$ (F : R = 7 : 3) system, but for the $K_2$MoO_4$-$K_2O{\cdot}6TiO_2$ (F : R = 7: 3) one, only the short fibers with ${\thickapprox}$ 2 mm long could be grown as the mixed phase of $K_2Ti_6O_{13}$ and $K_2Ti_4O_9$.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.24 no.2
• /
• pp.59-64
• /
• 2014

Crystallographic phases of Plasma electrolytic oxidized Al alloy, A1050, were investigated. The electrolyte of PEO was $Na_2Si_2O_3$ and KOH. Unipolar pulse, $ 2000{\mu}sec$ with $400{\mu}sec+420V$ impulse, were applied for 2 min, 5 min, 15 min, and 30 min. ${\gamma}-Alumina$, as well as ${\alpha}-alumina$, was main crystal phase. ${\gamma}-Alumina$ was appeared in the beginning, then the amount of ${\alpha}-alumina$ was increased with time, but the amount of ${\gamma}-Alumina$ remained constant without any increasing. So, it is concluded that plasma gas produce ${\gamma}-Alumina$ at the first, and then ${\gamma}-Alumina$ transform ${\alpha}-alumina$ finally. During the transformation, high temperature of micro plasma gives transformation energy.

• Korean Chemical Engineering Research
• /
• v.51 no.5
• /
• pp.561-567
• /
• 2013

Mixed hardwood chips were pre-pulping extracted with green liquor prior to kraft pulping in order to recover hemicelluloses for use as biofuels. This green liquor solution containing mainly sodium sulfide and sodium carbonate was applied at different alkali charges (expressed as $Na_2O$) of 0, 1, 3, and 5% on dry wood weight. The extractions were performed at $160^{\circ}C$ for residence times ranging from about 1-2 h to determine the effect of extraction severity on composition of the pre-pulping extract. The severity of hemicellulose extraction time and green liquor charge controls the concentration of acetic acid and monosaccharide sugars available for downstream processing, the accumulation of degradation products such as organic acids and furans in the extract. As the alkali charge was increased, the amount of acetate side chains on the hemicelluloses and the dissolved lignin in the extract increased but the carbohydrate and sugars in the extract decreased appreciably. Hot water extraction (0% alkali addition) released the greatest amount of carbohydrates, up to 29.80 g/L measured as component sugars, but resulted in the greatest decrease in pulp yield. Meanwhile, pre-pulping extraction with 3% green liquor increased the pulp yield while greatly reducing the component sugars to 7.08 g/L. Fundamental data obtained in this study will allow selection of optimum hemicellulose extraction conditions for integrating the extraction operation into the Kraft pulping process.

• Composites Research
• /
• v.29 no.1
• /
• pp.40-44
• /
• 2016

Nuclear fuel cladding used in a nuclear power plant must possess superior oxidation resistance in the coolant atmosphere of high temperature/high pressure. However, as was the case for the critical LOCA (loss-of-coolant accident) accident that took place in the Fukushima disaster, there is a risk of hydrogen explosion when the nuclear fuel cladding and steam reacts dramatically to cause a rapid high-temperature oxidation accompanied by generation of a huge amount of hydrogen. Hence, an active search is ongoing for an alternative material to be used for manufacturing of nuclear fuel cladding. Studies are currently aimed at improving the safety of this cladding. In particular, ceramic-based nuclear fuel cladding, such as SiC, is receiving much attention due to the excellent radiation resistance, high strength, chemical durability against oxidation and corrosion, and excellent thermal conduction of ceramics. In the present study, cladding with $SiC_f/SiC$ protective films was fabricated using a process that forms a matrix phase by polymer impregnation of polycarbosilane (PCS) after filament-winding the SiC fiber onto an existing Zry-4 cladding tube. It is analyzed the oxidation and microstructure of the metal cladding with $SiC_f/SiC$ composite protective films using a drop tube furnace for thermal shock test.

• Journal of the Korean Magnetics Society
• /
• v.7 no.5
• /
• pp.243-248
• /
• 1997

The effect of $O_2$ partial pressure on microstructure and soft magnetic properties of as-deposited Fe-Hf-O thin film alloys, which are produced by rf magnetron sputtering method in $Ar+O_2$ mixed gas atmosphere, are investigated. Saturation magnetization ($4{\pi}M_s$) of Fe-Hf-O film were decreased with increasing $O_2$ partial pressure, the best soft magnetic properties exhibit at $O_2$ partial pressure of 10%. With further increase of $O_2$ partial pressure, soft magnetic properties decreased continuously. The $Fe_{82}Hf_{3.4}O_{14.6}$ film with $P_{O2}=10%$ exhibits good soft magnetic properties with $4{\pi}M_s=17.7kG$, $H_c=0.7Oe$ and ${\mu}_ {eff}$ (1~100 MHz)=2,500, respectively. The addition of O is effective in grain refinement. In case of $P_{O2}=15%$, it is observed that $Fe_3O_4$ compound is formed and high frequency soft magnetic properties are decrease. The electrical resistvity($\rho$) of Fe-Hf-O film is increased with increasing $O_2$ partial pressure. Electrical resistivity of $Fe_{82}Hf_{3.4}O_{14.6}$ film was 5 times higher than that of the film without oxygen. Thus, it is considered that the good magnetic properties of $Fe_{82}Hf_{3.4}O_{14.6}$ film results from decreasing the $\alpha$-Fe grain size by precipitates (Hf and O), high electrical resistivity.

• Journal of the Korean Chemical Society
• /
• v.34 no.1
• /
• pp.51-62
• /
• 1990

Pentadentate Schiff base cobalt(II) complexes; Co(II)(Sal-DET) and Co(II)(Sal-DPT) were synthesized and these complexes were allowed to react with dry to form oxygen adducts of cobalt(II) complexes such as [Co(III)(Sal-DET)]$_2O_2$ and [Co(III)(DPT)]$_2O_2$ in aprotic solvents. These complexes have been identified by IR spectra, TGA, DSC, magnetic susceptibility measurements, and elemental analysis. It has been found that the oxygen adadduct complexes of $\mu$-peroxo type have hexaccordinated octahedral configuration with pentadentate schiff base cobalt(II) and oxygen, but the mole ratio of oxygen to cobalt(III) complexes of first step for oxygen adduct formation reaction of cobalt(II) complexes in aprotic solvents are 1:1. The redox reaction processes of Co(II)(Sal-DET), Co(II)(Sal-DPT), and oxygen adduct of cobalt(II) complexes were investigated by cyclic voltammetry and DPP method with glassy carbon electrode in 0.1M TEAP-DMSO and 0.1M TEAP-pyridine. As a result the reduction reaction processes of Co(III)/Co(II) and Co(II)/Co(I) for cobalt(II) complexes and oxygen adducts of cobalt(II) complexes are two irreversible steps of one eletron process, and reaction processes of oxygen for oxygen adducts complexes were quasireversible and redox range of potential was $E_{pc}$ = -0.97V∼-0.86V and $E_{pa}$ = -0.87V ∼ 0.64V.

• Journal of Life Science
• /
• v.16 no.4
• /
• pp.605-611
• /
• 2006

To investigate the possible use of probiont in fish farming industry, a bacterium with inhibitory effect against Vibrio anguillarum was isolated from gastrointestinal tract of the marine fish of yellow tail. It was identified to be Bacillus amyloliquefaciens H41 based on biochemical and physiological characterization. The optimal growth conditions of the isolated strain were 1% peptone, 1.5% yeast extract, 1% sucrose, 0.5% NaCl, 0.05% $MgSO_4{\cdot}7H_20$, pH 7.0-8.0, and 20 hr of incubation between $28-35^{\circ}C$ under aeration. The culture supernatant of the isolated strain showed inhibition activity against V. anguillarum. Inhibition activity was cleared by forming a clear zone by a paper-disk method. The maximal production of growth inhibition factor was induced by cultivation under 1% peptone, 1.5% yeast extract, 1% sucrose, 1% NaCl, 0.05% $MgSO_4{\cdot}7H_20$, pH 7.5 and at $35^{\circ}C$. The highest growth inhibition factor production was observed after 16-24 hr cultivation under aeration. The culture supernatant of the isolated strain showed inhibition activity whereas no inhibition activity was shown from the standard B. amyloliquefaciens KCTC 1724 strain. The growth inhibition affected only against V. anguillarum among other pathogenic Vibrios tested here.