• KSBB Journal
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• 제10권2호
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• pp.170-175
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• 1995

Methylobacterium organophilum을 이용하여 메탄 올로부터 고점성 다당류의 생산에 대한 질소원 이용의 통력학척 분석을 유가식 배양에서 수행하였다. 발효중 세포는 배지 중에 첨가된 질소원이 고갈된 후에도 계속 성장하였고, 에틸란은 질소원 고갈조건 하에서만 생성되였다 세포 성장은 배양초기에 첨가 한 질소원인 암모니아의 농도에 비례적으로 이루어 졌으나, 에릴란 생산은 첨가한 암모니아 농도가 $0.75g/\ell$ 이상에서는 오히려 현저하게 감소하였다. 초기 암모니아 농도가 높아질수록, 비세포중식 속도, 비산물생성 속도, 비기질소비 속도가 감소하였다. 높 은 암모니아 농도의 발효 속도들에 대한 저해작용을 감소시키기 위해, 질소원을 일정농도(암모니아 농도=$0.15g/\ell$) 이하로 유지시키면서 공급하는 유가식 배양법으로 메틸란의 농도를 $12.5g/\ell$ 까지 증가시킬 수있었다.

• 한국결정성장학회지
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• 제10권4호
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• pp.324-329
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• 2000

상온에서 $Cs^+$ ion sputtering에 의해 발생된 탄소 음이온 빔과 Kaufmann type ion source를 이용하여 발생된 수소 양이온 빔을 Si기판 위에 동시에 증착함으로써 얻어지는 DLC 박막의 특성을 분석하여 DLC 박막의 증착에 미치는 수소 이온의 영향을 관찰하였다. 수소 가스의 flow rate을 0 sccm부터 12 sccm까지 변화 시킴에 따라 박막 내에 포함되는 수소의 양이 증가하였으며, 수소의 증가에 따라 박막 내에 $sp^2$구조가 증가하는 것을 알 수 있었다. 수소에 의한 $sp^2$결합이 증가되는 현상은 증착시 박막 내에 주입되는 수소의 양이 CVD에 비해 매우 적은 양이지만, 상대적으로 높은 에너지를 지니고 기판에 충돌하기 때문에 물리적 에너지 전달 효과가 DLC 박막의 형성에 크게 작용하였음을 알 수 있었다.

• KSBB Journal
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• 제11권3호
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• pp.329-339
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• 1996

The effects of ammonium ion on cell growth kinetics, monoclonal antibody productivity, and cell metabolism of hybridoma cells were investigated. The mouse-mouse hybridoma cell line VlIIH-8 producing mouse IgG2a was used as a model system. Ammonium ion showed an inhibitory effect on cell growth and monoclonal antibody production. New immobilized adsorbents were developed for the reduction of the inhibitory effect of ammonium ion. The ammonium ion selective zeolite, Phillipsite-Gismondine was entrapped in calcium alginate bead or in dialysis membrane and applied to the hybridoma cell culture system for the in situ removal of ammonium ion from culture media. The effects of ammonium the both serum supplemented and serum free media on the cell growth were studied by applying immobilized adsorbents of calcium alginate bead type. The results demonstrated a substantial enhancement in cell growth. Applying immobilized adsorbents of dialysis membrane type to serum supplemented media also resulted in the stimulation of cell growth, cell viability and monoclonal antibody production.

• Tribology and Lubricants
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• 제26권2호
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• pp.122-128
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• 2010

Focused Ion Beam (FIB) has been used for site-specific TEM sample preparation and small scale fabrication. Moreover, analysis on the surface microstructure and phase distribution is possible by ion channeling contrast of FIB with high resolution. This paper describes FIB applications and deformed surface structure induced by sliding. The effect of FIB process on the surface damage was explored as well. The sliding experiments were conducted using high purity aluminum and OFHC(Oxygen-Free High Conductivity) copper. The counterpart material was steel. Pin-on-disk, Rotational Barrel Gas Gun and Explosively Driven Friction Tester were used for the sliding experiments in order to investigate the velocity effect on the microstructural change. From the FIB analysis, it is revealed that ion channeling contrast of FIB has better resolution than SEM and the tribolayer is composed of nanocrystalline structures. And the thickness of tribolayer was constant regardless of sliding velocities.

• 한국세라믹학회지
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• 제32권10호
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• pp.1093-1102
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• 1995

Water-soluble phosphate glasses containing Ag or Cu ion were prepared through melting process. Then the powdered glass samples were dissolved in D.I. water at room temperature with changing the dissolution time. In terms with the glass composition, dissolution characteristics, bactericidal effects and cytotoxicities were investigated. Dissolved amounts increased uniformly with dissolution time, and the dissolution rate was higher for ternary glass than for binary glass and with less metal oxide amount. And the dissolution rate of the glass with Ag ion was higher than that with Cu ion, and the bactericidal effect of the glass with Ag ion was also greater. Solution with more than 25 ppm of Ag was observed to have strong cytotoxicity to L929, and solutions of lower Ag concentration or with Cu seemed to have little cytotoxicity.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 춘계학술대회논문집
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• pp.368-376
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• 2009

Studies on the effect of the wall-ion, wall-water, water-ion and ion-ion interaction on properties of water and ions in nano-channels have been performed through the use of different kinds of ions or different models of potential energy between wall-ion or wall-water. On this paper, we address the effect of water-wall interaction potential on the properties of confined aqueous solution by using the molecular dynamics (MD) simulations. As the interaction potential energies between water and wall we employed the models of the Weeks-Chandler-Andersen (WCA) and Lennard-Jones (LJ). On the MD simulations, 680 water molecules and 20 ions are included between uniformly charged plates that are separated by 2.6 nm. The water molecules are modeled by using the rigid SPC/E model (simple point charge/Extended) and the ions by the charged Lennard-Jones particle model. We compared the results obtained by using WCA potential with those by LJ potential. We also compared the results (e.g. ion density and electro-static potential distributions) in each of the above cases with those provided by solving the Poisson-Boltzmann equation.

• 분석과학
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• 제8권4호
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• pp.481-486
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• 1995

Quenching experiments by photoinduced electron transfer between a charged donor and a neutral acceptor were carried out in acetonitrile, dichloromethane and mixed solvents of acetonitrile and dichloromethane. Tris(2, 2'-bipyridine) ruthenium(II) ($[Ru(bpy)_3]^{2+}$) which has 2+ charge and dicyanobis (2, 2'-bipyridine) ruthenium(II) ($Ru(bpy)_2(CN)_2$) which has no charge were used as electron donors, and a series of tris(${\beta}$-diketonato) ruthenium (III) was used as acceptor. In dichloromethane, $[Ru(bpy)_3]^{2+}$ and its counter ions ($ClO{_4}^-$) form ion pair. In the estimate of ${\Delta}G$ of electron transfer, the electrostatic potential between counter ions and product ion pair produced by electron transfer must be taken into account. A similar effect of counter ions was found in mixed solvents of 10, 30, 50, 70 and 90% acetonitrile ratio in volume. The effect of counter ion on ${\Delta}G$ became smaller with the increase in acetonitrile ratio. The result in mixed solvents suggests that $[Ru(bpy)_3]^{2+}$ and its counter ions form ion pair even in 90% acetonitrile solution.

• 한국환경과학회지
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• 제16권8호
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• pp.907-912
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• 2007

Ion exchange resin was used to remove silica ion at ultralow concentration. The effects of temperature, type of ion exchange resin and single/mixed-resin systems on removal efficiency were estimated. As temperature increased, the slope of concentration profile became stiff, and the equilibrium concentration was higher. In the single resin system, the removal of silica was continued up to 400 min, but the silica concentration was recovered to initial concentration after 400 min due to the effect of dissolved $CO_2$. In the mixed-resin system it took about 600 min to reach equilibrium. Because of faster cation exchange reaction than anion exchange reaction, the effect of $CO_2$ could be removed. Based on the experimental results carried out in the mixed-resin system, the selectivity coefficients of silica ion for each ion exchange resin were calculated at some specific temperatures. The temperature dependency of the selectivity coefficient was expressed by the equation of Kraus-Raridon type.

• 약학회지
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• 제38권2호
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• pp.211-217
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• 1994

Copper intoxication and disturbance of copper metabolism induced various oxygen-derived free radicals related damages. The effect of copper ion on xanthine oxidase activity and type conversion of the enzyme which is concerned to generation of reactive oxygen species, was investigated, It was observed that xanthine oxidase activity was increased by addition of copper ion in the reaction mixture in proportional to the concentration of the metal ion until $60\;{\mu}M$, while the enzyme activity was inhibited in higher concentration of copper treatment. On the other hand, xanthine dehydrogenase activity was inhibited by copper ion addition with concentration dependently. Preincubation of enzyme source with $30\;{\mu}M$ of copper ion, which concentration marked increased the xanthine oxidase activity, unchanged the enzyme activity and type conversion compare to control in vitro system. It was also observed that copper induced xanthine oxidase activity and the enzyme type conversion was protected by dithiothreitol and penicillamine. These results indicate that the increment of the type conversion of xanthine oxidase necessarilly need the presence of copper ion in enzyme assay system.

• 대한한의학회지
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• 제28권4호
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• pp.104-113
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• 2007

Background : Amygdalin is abundant in Armeniacae semen, and it is recently reported to treat cancers and relieve pain. But modus operandi of amygdalin at the level of neuron has not been reported, yet. Objective : This study aimed to find out the effect of amygdalin on glycine- and glutamate-induced ion currents in periaqueductal gray (PAG) neurons. And it was investigated that amygdalin participates in the regulation of the descending pain control system in the level of PAG neurons. Method : We investigated that the changes of glycine- and glutamate-induced ion currents in PAG neurons through application of lipopolysaccharides (LPS) and application of amygdalin with LPS by using the nystatin-perforated patch clamp method. Result : Application of LPS on PAG neurons resulted in increased glycine-induced ion current, and in decreased glutamate-induced ion current. In contrast, application of amygdalin with LPS resulted in decreased glycine-induced ion current increased by LPS, and increased glutamate-induced ion current decreased by LPS. Conclusion : Amygdalin from Armeniacae semen controls glycine- and glutamate-induced ion current by LPS in PAG neurons, and it is suggested that amygdalin participates in the regulation of the descending pain control system in the level of PAG neurons.