• Journal of Microbiology and Biotechnology
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• 제32권1호
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• pp.126-140
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• 2022

Stem cells can be applied usefully in basic research and clinical field due to their differentiation and self-renewal capacity. The aim of this study was to establish an effective novel therapeutic cellular source and create its molecular expression profile map to elucidate the possible therapeutic mechanism and signaling pathway. We successfully obtained a mesenchymal stem cell population from human embryonic stem cells (hESCs) cultured on chemically defined feeder-free conditions and treated with connective tissue growth factor (CTGF) and performed the expressive proteomic approach to elucidate the molecular basis. We further selected 12 differentially expressed proteins in CTGF-induced hESC-derived mesenchymal stem cells (C-hESC-MSCs), which were found to be involved in the metabolic process, immune response, cell signaling, and cell proliferation, as compared to bone marrow derived-MSCs(BM-MSCs). Moreover, these up-regulated proteins were potentially related to the Wnt/β-catenin pathway. These results suggest that C-hESC-MSCs are a highly proliferative cell population, which can interact with the Wnt/β-catenin signaling pathway; thus, due to the upregulated cell survival ability or downregulated apoptosis effects of C-hESC-MSCs, these can be used as an unlimited cellular source in the cell therapy field for a higher therapeutic potential. Overall, the study provided valuable insights into the molecular functioning of hESC derivatives as a valuable cellular source.

• 한국미생물·생명공학회지
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• 제17권2호
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• pp.85-87
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• 1989

토양으로부터 분리한 Xylose 발효효모 X-6-41 (Candida sp.)의 xylanase 효소생성 조건을 조사해 본 결과, 본 실험에 사용한 X-6-41 균주는 배지조성중 yeast extract 혹은 polypeptone이 첨가되면 xylanase 효소생성이 없었다. 즉 특정 아미노산인 isoleucine에 의해서는 그 생성이 억제되었고, tryptophan 25$\mu$g/$m\ell$ 농도의 존재하에서는 xylanase 생성이 증가했다.

• Journal of Microbiology and Biotechnology
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• 제2권2호
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• pp.129-134
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• 1992

Segregational instability of a recombinant plasmid, pDML6, encoding extracellular $\beta$-lactamase in Streptomyces lividans PD6 was characterized by growth kinetic analysis. The quantitative determination of the plasmid harbored in the mycelia was evaluated with mycelia fragmented mechanically, and also with colonies regenerated from protoplasts. Conditions for the formation of protoplasts and regeneration of protoplasts were established. The maximal specific growth rates of the host strain and the plasmid-harboring strain in a chemically defined medium without selection pressure were the same. The probability of plasmid loss from the harbouring cells was higher at higher growth rates. Mathematical models for the prediction of cell growth, substrate uptake, and accumulation of the cloned gene product were developed.

• 펄프종이기술
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• 제39권5호
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• pp.7-11
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• 2007

Kraft pulping of Trema orientalis (Nalita) was studied in order to find kinetic data for delignification. Pulping runs were carried out in the temperature range of $160-180\;^{\circ}C$ under constant and well-defined conditions. The delignification was found to be first order with respect to residual lignin and was chemically controlled. The rate of delignification reaction was increased 1.11-1.23 for $10\;^{\circ}C$ temperature increase in the range of $160-180\;^{\circ}C$ range. A mean value of 93% of lignin was removed at the transition between bulk and residual delignification. The influence of cooking temperature on the rate constant was expressed by an Arrhenius-type equation. The obtained activation energy of the delignification reaction was 6,164 cal/mol. The transition point between bulk and residual phase was shifted to lower lignin and carbohydrate yield with the increase of temperature.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.90.1-90.1
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• 2010

The design and fabrication of a metallic bipolar plate-gasket assembly for polymer electrolyte fuel cells (PEMFCs) is defined. This bipolar plate-gasket assembly was prepared by inserting a previously prepared bipolar plate in the specially designed gasket mold. For this aim, a proprietary fluoro-silicone based rubber was injected directly into the bipolar plate borders. Gaskets obtained like this showed the chemically / physically stable and the good sealibilty in typically operating PEM fuel cell conditions. And also, this bipolar plate-gasket assembly shows lots of advantages with respect to traditional PEMFCs stack assembling systems: useful application to automative stacking due to easy handling, reduced fabrication time, possibility of quality control and failed elements substitution. This bipolar plate-gasket assembly was evaluated in the short fuel cell stack and met the leakage requirement for normal operation both in short-term and in long-term operation. Especially, it was confirmed that this gasket could be applied successfully even in the high pressure FEM fuel cell systems(over 2.0 bar in absolute pressure).

• 한국정밀공학회지
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• 제25권6호
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• pp.40-46
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• 2008

Ultraprecision cutting of steels with geometrically defined single crystal diamond tools is handicapped by excessive tool wear. This paper presents a new approach to suppress the wear of single crystal diamond tool in cutting of steels. In general, it is said that the wear of diamond tool is caused by chemically reactive wear under high temperature and high pressure conditions. In order to suppress such chemical reactions, the time of contact between the diamond tool and the steel work in cutting was controlled by employing the intermittent cutting method such as fly-cutting. Series of intermittent cutting experiments have been carried out to control the tool-work contact time by changing one cycle of cutting length and cutting speed. The experimental results were shown that the tool wear was much dependent on the contact time regardless of the cutting speed, and that the wear was much suppressed by reducing the tool-work contact time. It is expected that the steels can be successfully cut with a single crystal diamond tool by controlling the contact time.

• Membrane and Water Treatment
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• 제4권1호
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• pp.27-51
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• 2013

During cleaning steps, ultrafiltration membranes are mechanically and chemically stressed. This may result in membrane degradations and failures. In this paper, polysulfone membranes were used to evaluate membrane deteriorations by commercial detergents in static conditions. Ageing of the membrane was simulated by immersing samples in solutions containing commercial detergents with various concentrations, temperatures and times defined by experimental designs. Indeed, an innovative approach in the chemical membranes ageing researches, based on methodological tools, was used in order to achieve significant ageing experiments without using an accelerated ageing protocol. The macroscopic changes were monitored by permeability measurements and mechanical strength tests coupled with a microscopic characterization by ATR-FTIR and HRSEM. The present work details results obtained for three commercial detergents: an alkaline, an acidic and an enzymatic detergent. It was found that the detergents used in the industrial advised conditions (concentration, temperature and time of contact) were not detrimental for membrane properties (permeability and elongation at break) and so for the quality of the produced water. Over the industrial cumulated time of contact, different ageing effects can be observed and compared with the ones induced by NaOCl.

• Journal of Microbiology and Biotechnology
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• 제23권9호
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• pp.1327-1338
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• 2013

The humanized anti-hepatocyte growth factor (HGF) monoclonal antibody (mAb) YYB-101 is a promising therapeutic candidate for treating various cancers. In this study, we developed a bioprocess for large-scale production of YYB-101 and evaluated its therapeutic potential for tumor treatment using a xenograft mouse model. By screening diverse chemically defined basal media formulations and by assessing the effects of various feed supplements and feeding schedules on cell growth and antibody production, we established an optimal medium and feeding method to produce 757 mg/l of YYB-101 in flask cultures, representing a 7.5-fold increase in titer compared with that obtained under non-optimized conditions. The optimal dissolved oxygen concentration for antibody production was 70% $pO_2$. A pH shift from 7.2 to 7.0, rather than controlled pH of either 7.0 or 7.2, resulted in productivity improvement in 5 L and 200 L bioreactors, yielding 737 and 830 mg/ml of YYB-101, respectively. The YYB-101 mAb highly purified by affinity chromatography using a Protein A column and two-step ion exchange chromatography effectively neutralized HGF in a cell-based assay and showed potent tumor suppression activity in a mouse xenograft model established with human glioblastoma cells.

• 한국균학회지
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• 제25권2호통권81호
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• pp.133-142
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• 1997

Phellinus igniarius의 화학합성배지 조성 및 배양조건의 최적화 실험을 실시하였다. 또한 곡물에서 담자균사체를 배양하는 고체재료 발효방법을 개발함으로써, 기능성식품의 이용 가능성을 검토한 결과는 다음과 같다. Phellinus igniarius의 최적 영양배지로는 malt extract 7.0%, bacto soytone 0.3%, yeast extract 0.2%의 조합이었다. 그러나 대부분의 버섯 영양배지에 공통으로 첨가되는 무기염류$(KH_2PO_4,\;0.046%,\;K_2HPO_4\;0.1%,\;MgSO_4{\cdot}7H_2O\;0.05%)$의 첨가는 균사생장에 별 영향을 미치지 않는 것으로 나타났다. 균사생장의 최적 배양온도는 $28^{\circ}C$였으며, 균사생장 최적 pH는 7.0으로 나타났다. 담자균사체의 대량배양 조건 실험을 실시한 결과, 냉침에 의해 최대수화에 도달한 곡물을 배양용기에 담고, 액체배양 후 균질화한 담자균사체를 곡물에 접종함으로써 접종초기 짧은 시간에 균사가 완전히 활착 되도록 할 수 있었다. 또한 균사 배양중기에 멸균 증류수를 첨가함으로써 균사의 활력을 유지시킬 수 있었다. Phellinus igniarius가 배양된 곡물에서 균사체량을 나타내는 glucosamine의 함량은 율무>보리>흑태>밀>메주콩>현미>수수>찹쌀의 순이었다.

• 암석학회지
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• 제10권3호
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• pp.157-171
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• 2001

다검출기 유도결합 플라즈마 질량분석기(Multi-Collector Inductively Coupled Plasma Mass Spectrometer; MC/ICP/MS; AXIOM MC 모델)를 이용한 Pb동위원소 분석 시 고려 사항인 Pb/Ti 비율, Pb농도 영향, 기질 원소 영향을 살펴보고, NBS 981 용액을 2001년 3월부터 8월까지 42번 측정하여 정확도 및 재현성 을 검토하였다. 그리고 암석, 청동기 및 퇴적물 시료의 Pb 동위원소를 분석하여 열 이온화 질량분석기(TIMS) 자료와 비교하였다. NBS 981 Pb 200 ng으로 동위원소 비율을 측정하였을 때 $^{206}$ $Pb^{204}$ , $Pb^{207}$ //$Pb^{204}$ , $Pb^{208}$ $Pb^{204}$ Pb 비율은 약 500 ppm(2sd), $^{/}$$207^{206}$ Pb 및 $Pb^{208}$ $Pb^{206}$Pb 비율은 100~200 ppm(2sd)의 재현성을 얻을 수 있었다. Pb등위원소 분석의 정확도 및 재현성 측면에서 최적 조건은 1) Pb/Tl농도 비가 10 이고 2) Pb농도가 100 ng/ml 이상이며 3) 질량 분별 효과는 지수 법칙에 따라 보정하고 이 때 사용된 Tl의 동위원소 비율($^{205}$ $Tl^{203}$ Tl)은 2.3887이며 질량 분별 인자는 측정된 $208^{Pb}$ $^{206}$ 및 $Pb^{205}$ $Tl^{203}$ Tl 비율로부터 경험적으로 구해진 Pb의 인자를 이용하는 것이었다. 시료 중의 기질 원소들(matrix elements)에 의한 Pb 동위원소 비율의 영향은 없는 것으로 판단되며, TIMS와 비교된 시료들에 대하여 Pb 등위원소들은 측정 오차 범위 내에서 잘 일치하였다. 즉, MC/ICP/MS에 의한 Pb 동위원소 분석은 시료 전처리 단계를 줄여도 WS와 유사한 정밀도를 얻을 수 있어 신속한 분석방법이라 할 수 있다.다.