• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.93-96
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• 2009

In the cathode channel of a PEM fuel cell, the local concentration of oxygen near the gas diffusion layer (GDL) decreases in streamwise direction due to chemical reactions, which degrades the efficiency of the oxygen consumption and overall fuel cell efficiency. We numerically studied the influence of the swirling flow generated by a slanted groove mixer (SGM) on the concentration distribution of oxygen. We found that the swirling flow can increase the concentration of oxygen near the GDL, and subsequently improves the oxygen consumption rate.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.181-184
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• 2001

The biological fixation of carbon dioxide using microalgae have many advantages over chemicals and remove carbon dioxide simultaneously. A ketocarotenoid astaxanthin is hyper-accumulated in the green freshwater microalga, Haematococcus pluvialis. In the present study, the combine effects of carbon dioxide concentration and light intensity on the growth of H. pluvilais were investigated. The carbon dioxide concentration above 10% caused a severe inhibition and around 5% is optimal for growth. Adaptation to high concentration of carbon dioxide enhanced the $CO_2$ tolerance. Specific growth rate calculated differently based upon cell number or dry weight because of the distinctive life cycle patterns of H. pluvialis : small-sized motile green cell and thick cell walled red cyst cell. Based on the light dependence of H. pluvialis, internally illuminated air-lift photobioreactor was designed and operated. Gradual increase of light supply gave more active growth and more effective productivity of astaxanthin than constant light supply.

• KSBB Journal
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• 제13권5호
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• pp.585-592
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• 1998

The effect of intracellular Ca2+ level on the hybridoma cell growth and monoclonal antibody(MAb) production was examined. For the manipulation of intracellular Ca2+ concentration, the cells were treated with A23187, ryanodine, and thapsigargin at about 1x106 cells/mL. The treated cells were recultivated by using the Iscove's Modified Dulbecco's Medium(MDM) containing 1.49mM CaCl2. The ryanodine-treated cells showed better cell growth, MAb concentration, and specific MAb productivity than others. In comparison with control, the maximum cell concentration, MAb concentration, and specific MAb productivity were increased by 40.6%, 48.1% and 83.3%, respectively. Confocal microscopic images of Fura-2/AM loaded cells indicate that the increase in intracellular Ca2+ level can enhance the MAb productivity by allowing the calcium influx into the endoplasmic reticulumn.

• Journal of Microbiology and Biotechnology
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• 제20권12호
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• pp.1677-1680
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• 2010

The harmful effects of succinic acid and oxidative stress on cell growth were determined during batch fermentation with Mannheimia succiniciproducens LPK7, a powerful succinic acid-producing strain, and conditions were optimized to minimize these effects. In terms of toxicity, the cell concentration decreased as the concentration of succinic acid increased. By changing the pH from 6.5 to 7 during fermentation, the cell concentration increased by about 10%, and the level of succinic acid production was 6% higher than that of the control. In addition, by introducing protectants, the cell concentration increased by about 10%, and the level of succinic acid produced was increased by 3%.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권6호
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• pp.603-606
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• 2005

Ralstonia eutropha NCIMB 11599 and ATCC 17699 were grown, and their productions of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] compared. In flask cultures of R. eutropha NCIMB 11599, cell concentration, P(3HB-co-4HB) concentration and polymer content decreased considerably with increases in the ${\gamma}-butyrolactone$ concentration, and the 4HB fraction was also very low (maximum 1.74 mol%). In fed-batch cultures of R. eutropha NCIMB 11599, glucose and ${\gamma}-butyrolactone$ were fed as the carbon sources, under a phosphate limitation strategy. When glucose was fed as the sole carbon source, with its concentration controlled using an on-line glucose analyzer, 86% of the P(3HB) homopolymer was obtained from 201g/L of cells. In a two-stage fed-batch culture, where the cell concentration was increased to 104g/L, with glucose fed in the first step and constant feeding of ${\gamma}-butyrolactone$, at 6g/h, in the second, final cell concentration at 67h was 106g/L, with a polymer content of 82%, while the 4HB fraction was only 0.7mol%. When the same feeding strategy was applied to the fedbatch culture of R. eutropha ATCC 17699, where the cell concentration was increased to 42 g/L, by feeding fructose in the first step and ${\gamma}-butyrolactone$ (1.5g/h) in the second, the final cell concentration, polymer content and 4HB fraction at 74h were 51g/L, 35% and 32 mol%, respectively. In summary, R. eutropha ATCC 17699 was better than R. eutropha NCIMB 11599 in terms of P(3HB-co-4HB) production with various 4HB fractions.

• 대한한방부인과학회지
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• 제21권3호
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• pp.18-33
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• 2008

Purpose: The research is to investigate the effect of TFE on apoptosis of human-derived breast cancer cells, to find out the relationship with apoptosis. Methods: Human-derived breast adenocarcinoma cell line, MCF-7 cells were treated by TFE with various concentration. The inducement effect of TFE on cell apoptosis was observed with MTT assay and the relationship between the treatment and apoptosis was investigated with FACS analysis, TUNEL assay and DNA laddering assay and the change in the protein levels of PARP and caspase-3 activities were also observed. The release of cytochrome-c was observed to find out the pathway of apoptosis induced by TFE. Results: The cell apoptosis was significantly induced in MCF-7 cells treated with TFE in concentration-dependent and time-dependent manner. It was verified by FACS analysis, TUNEL assay, DNA laddering assay that cell-death was caused not by necrosis but by apoptosis. The activity of PARP and caspase were increased concentration-dependently. The release of cytocrome-c was decreased in proportion to the concentration of the fruit extract. It therefore demonstrated that mitochondria were involved in apoptosis induced by TFE. The appearance of Bcl-2 protein was decreased concentration-dependently. Conclusion: The treatment by TFE induced apoptosis of human breast adenocarcinoma cell line, MCF-7. It seems likely that cell-death was caused by apoptosis and mitochondria were involved in it. The mechanism of protein change causing apoptosis seems related to the inhibition of Bcl-2 protein, the promotion of inversion from cytochrome-c into cytosol, the activation of caspase and the promotion of PARP cleavage.

• 대한약침학회지
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• 제25권4호
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• pp.390-395
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• 2022

Objectives: Sweet bee venom (sBV) is purified from Apis mellifera, containing a high level of melittin-its main component. It has been used as a therapeutic agent for pain relief and anti-inflammation, as well as for treating neuronal abnormalities. Recently, there have been studies on the therapeutic application of sBV for anticancer treatment. In the present study, we investigated the pharmacological effect of sBV treatment in A549 human lung cancer cells. Methods: We used microscopic analysis to observe the morphological changes in A549 cells after sBV treatment. The MTT assay was used to examine the cytotoxic effect after dose-dependent sBV treatment. Molecular changes in sBV were evaluated by the expression of apoptosis marker proteins using western blot analysis. Results: Microscopic analysis suggested that the growth inhibitory effect occurred in a dose-dependent manner; however, cell lysis occurred at a concentration over 20 ㎍/mL of sBV. The MTT assay indicated that sBV treatment exhibited a growth inhibitory effect at a concentration over 5 ㎍/mL. On fluorescence activated cell sorting analysis, G0 dead cells were observed after G1 arrest at treatment concentrations up to 10 ㎍/mL. However, rapid cell rupture was observed at a concentration of 20 ㎍/mL. Western blot analysis demonstrated that sBV treatment modulated the expression of multiple cell death-related proteins, including cleaved-PARP, cleaved-caspase 9, p53, Bcl2, and Bax. Conclusion: sBV induced cell death in A549 human lung cancer cells at a pharmacological concentration, albeit causing hemolytic cell death at a high concentration.

• KSBB Journal
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• 제8권5호
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• pp.478-482
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• 1993

LSM을 이용하여 KA112 균주의 고농도 배양을 시도하였다. Separator로는 hollow fiber를 사용하였고 reactor로는 Celligen을 이용하였다. Wroking volume 1리터로 10일간 배양하여 최고 세포농도가 회분식 배양에 비하여 10배 이상 증가한 $2.1\times10^7$ cells/ml이었고, 항체의 농도는 4.5배 정도 높았다. 최고 feed rate에서 항체생산속도는 회분식 배양보 다 9배 높았으며 배양 중 glucose농도가 Ig/e 이상일 때 specific productivity가 증가하였고, 1 g/6 이하얼 때 세포성장은 영향을 받지 않으냐 spe­c cific prodictivity는 감소하였다.

• 한국미생물·생명공학회지
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• 제26권2호
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• pp.167-172
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• 1998

의료용 아미노산인 오르니틴을 생산하는, 용존산소농도와 pH가 일정하게 유지되는 회분식 배양에서 산화환원전위의 시간에 따른 변화를 주요 발효 상태변수들(균체, 포도당, 오르니틴 농도)과 함께 관찰하였다. 산화환원전위는 배양상태를 반영하는 네 개의 다른 구간을 나타내었으며 특히 균체농도의 변화와 밀접한 관계가 있으며 오르니틴 농도에 의해서도 영향을 받음을 알 수 있었다. 산화환원전위와 발효상태변수들과의 상관관계를 구하기 위해 먼저 오르니틴 및 포도당이 산화환원전위에 미치는 영향을 별도의 실험을 통해 알아보았다. 이들 실험 결과들을 바탕으로 하여 산화환원전위의 발효상태변수에 대한 상관관계를 제시하였다. 이 상관관계는 산화 환원전위, 포도당 농도, 균체농도의 on-line data로부터 오르니틴 농도를 on-line 추정하는데 이용될 수 있을 것으로 기대된다.

• 한국수소및신에너지학회논문집
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• 제24권6호
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• pp.495-509
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• 2013

In this study, we develop a one-dimensional (1-D), two-phase, transient-thermal DMFC model to investigate the effect of methanol concentration fluctuation that usually occurs in active-type direct methanol fuel cell (DMFC) systems. 1-D transient simulations are conducted and time-dependent behaviors of DMFCs are analyzed under various DMFC operating conditions such as anode/cathode stoichiometry, cell temperature, and cathode inlet humidification. The simulation results indicate that the effect of methanol concentration fluctuation on DMFC performance can be mitigated by proper control of anode/cathode stoichiometry, providing a guideline to optimize operating conditions of active DMFC systems.