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박정극,송계용,권순용,Kyung-Min Choi,Young-Kwon Seo,윤희훈,Hwa-Sung Lee 한국생물공학회 2007 Biotechnology and Bioprocess Engineering Vol.12 No.6
To support and enhance the in vitro growth and activity of mesenchymal stem cells (MSCs), the cell culture medium may be supplemented with various proteins and factors to mimic the physiological environment in which the cells optimally proliferate and differentiate. In this study, the effects of mechanical factors on cellular metabolic responses were investigated experimentally using a bioreactor. The effects of various chemical factors, such as growth factors, cytokines, and hormones, were also investigated. Based on previous reports demonstrating the important roles of mechanical factors in the growth and activity of MSCs, we sought to evaluate the effects of mechanical stimuli on the proliferation of bone marrow-derived MSCs using a cell training bioreactor that imposed cyclic mechanical stretch, with parameters of 240 min/day, 0.03 Hz, and 5~15% strain. The application of cyclic stretch (5~15% strain) to the MSCs enhanced their proliferation during the early stage (3 days), but not the late stage (14 days), of batch culture. Mechanical stretch did not increase the release of lactate dehydrogenase (LDH) from the MSCs during culture. Appropriate levels of mechanical stretch (5~10% strain) increased collagen synthesis, but did not alter MSC surface antigen expression. It is thought that the appropriate level of mechanical stretch was able to serve as a potent positive modulator of MSC proliferation during the initial stages of culture.
FTIR을 이용한 상용 흡착제의 바이오가스 실록산 흡착 특성에 관한 실험적 연구
박정극,허광범,이정근,이남훈 한국폐기물자원순환학회 2018 한국폐기물자원순환학회지 Vol.35 No.6
Removal of siloxane compounds is very important to protecting the biogas energy conversion system from decreased efficiency and parts damage. Among various siloxane removal technologies, adsorption towers are mostly used for performance and ease of operation. However, due to the difficulty of measuring the concentration of siloxane compounds in the gas stream and the complicated matrix of siloxane compounds, adsorption characteristics are not well known. In this study, the adsorption characteristics for multi siloxane components are experimentally studied. Four siloxane components are vaporized in the nitrogen stream supplied continuously to a lab-scale adsorption tank with commercially available silica gel or activated carbon and an FTIR (Fourier-transform infrared spectroscopy) analyzer was used for the online siloxane analysis to find out the adsorption characteristics. While a mixture of L2, L5, D4 and D5 adsorption capacity of silica gel and activated carbon are similar -11.13 and 11.56wt% respectively-adsorption characteristics of each adsorbent was well distinguished in terms of breakthrough behavior. Silica gel shows sequential breakthrough for each siloxane compound and a more noticeable unique time range for Rc > 1, while relatively simultaneous breakthrough was shown for activated carbon adsorbents.
박정극,김영진,양은경,장이섭,유보영,서영권,이두훈,신윤호,이경미,송계용,서성준,왕성주,박창서 한국생물공학회 2003 Biotechnology and Bioprocess Engineering Vol.8 No.2
Obtaining a sufficient amount of healthy keratinocytes from a small tissue is difficult. However, ORS cells can be a good source of epithelium since they are easily obtainable and patients do not have to suffer from scar formation at donor sites. Accordingly, the current study modified the conventional primary culture technique to overcome the low propagation and easy aging of epithelial cells during culturing. In a conventional primary culture, the average yield of human ORS cells is 2.1 x 103 cells/follicle based on direct incubation in a trypsin (0.1%)/EDTA (0.02%) solution for 15 min at 37oC, however, our modified method was able to obtain about 6.9 x 103 cells/follicle using a two-step enzyme digestion method involving dispase (1.2 U/mL) and a trypsin (0.1%)/EDTA (0.02%) solution. Thus, the yield of primary cultured ORS cells could be increasd three times higher. Furthermore, a total of 2.0 x 107 cells was obtained in a serum-free medium, while a modified E-medium with mitomycin C-treated feeder cells produced a total of 6.3 x 107 cells over 17 days when starting with 7.5 x 104 cells. Finally, we confirmed the effectiveness of our ORS cell isolation method by presenting their ability for reconstructing the bioartificial skin epithelium in vitro.
산소전달계수 및 경험적 기질공급방법이 Baker's Yeast 의 유가식배양에 미치는 영향
박정극,윤문영 한국화학공학회 1999 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.37 No.1
Baker's yeast 유가식배양에서 최적의 수율과 생산성을 위하여 K_La(산소전달계수)와 3가지 경험적 기질공급방법의 영향을 조사하였다. 발효기내의 교반속도(100에서 600rpm)와 통기속도(1.0, 1.5, 2.0vvm)를 변화시키면서 K_La값을 측정하였고, 통기속도는 1.5vvm으로 일정하게 유지하고 각각의 교반속도(300에서 600rpm)에서 유가식배양을 실시하여 수율과 생산성을 조사하였다. K_La값은 교반속도와 통기속도에 비례하여 빠르게 증가하였다. 기질공급 pattern은 sigmoidal한 공급이 최적으로 나타났고, 최적의 총 기질공급량과 생산성은 K_La값에 크게 의존하였으나 500rpm부터는 일정한 값을 유지하였고, 수율을 K_La값이 증가함에 따라 약간씩 감소하는 경향을 나타냈다. 이것은 molasses 투입량 증가에 의한 molasses내에 존재하는 저해작용물질축적과 발효대사산물의 축적, 점도의 증가, cell농도의 증가 등에 의해 cell 성장속도와 산소전달속도가 감소한 것으로 사료되고, 본 발효기는 500에서 600rpm부근에서 운전하는 것이 최적조건으로 판단된다. The effect of K_La(Oxygen Transfer Coefficient) and substrate feeding policy on the optimum cell yield and productivity was investigated in the baker's yeast fed-batch cultivation. K_La was measured at various agitation speed(100 to 600 rpm) and aeration rate (1.0, 1.5, 2.0 vvm), and the cell yield and productivity of fed-batch cultivation was determined at each agitation speeds (300 to 600 rpm) and constant aeration rate (1.5 vvm). K_La value was increased proportionally with increasing agitation speeds and aeration rate. Substrate feeding pattern was optimum in sigmoidal feeding. The optimum total fed-sugar and productivity was largely dependent on the K_La and did not change at above 500rpm, and the cell yield was decreased gradually as the K_La increased. It is considered that the increase of the accumulation of inhibitory substances in the molasses by the increase of molasses feeding, the accumulation of fermentation metabolites, the viscosity and cell concentration of fermentation broth, and so forth was decreased the cell growth rate and oxygen transfer rate. So, the optimum operation condition of this fermentor was estimated to near 500 to 600 rpm.
유기용매 추출법에 의한 포플라의 전처리 및 당화 조건의 최적화
박정극,전영삼 東國大學校 1990 論文集 Vol.29 No.-
The effect of the pretreatment by solvent extraction with various solvent on the saccharification of poplar (Populus euramericana)was studied. The solvent system was phenol/H_2O (uncatalyzed, HCl and NaOH catalyzed), butanol/H_2O, ethanol/H_2O and ethylendiamine/H_2O solvent system. When the poplar was pretreated by phenol/H_2O uncatalyzed system, the best result of the enzymatic saccharification was total of 43.87 g/L reducing sugar produced and 83.35% of carbohydrated conversion was obatined at 190℃, 60 minutes. Total wood yield and the lignin removal were 46.3% and 96.17%, respectively. The use of acid, base catalyst and the others solvents was unsuitable to increase the efficiency of saccharification.
박정극,송계용,김기호,이희구,양은경,안재일,장인근,이두훈,Young-Kwon Seo,Hee-Hoon Yoon,Youn-Ho Shin,Jae-Chan Kim 한국생물공학회 2005 Biotechnology and Bioprocess Engineering Vol.10 No.3
Many researchers have employed cryopreserved amniotic membrane (CAM) in the treatment of a severely damaged cornea, using corneal epithelial cells cultured on an amniotic membrane (AM). In this study, two Teflon rings were made for culturing the cells on the LAM and CAM, and were then used to support the AM, which is referred to in this paper as an Ahns AM supporter. The primary corneal epithelial cells were obtained from the limbus, using an explantation method. The corneal epithelium could be reconstructed by culturing the third-passage corneal epithelial cells on the AM. A lyophilized amniotic membrane (LAM) has a higher rate of graft take, a longer shelf life, is easier to store, and safer, due to gamma irradiation, than a CAM. The corneal epithelium reconstructed on the LAM and CAM, supported by the two-Teflon rings, was similar to normal corneal epithelium. However, the advantages of the LAM over that of the CAM make the former more useful. The reconstruction model of the corneal epithelium, using AM, is considered as a good in vitro model for transplantation of cornel epithelium into patients with a severely damaged cornea.