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Cellulose nanofibers for magnetically-separable and highly loaded enzyme immobilization
Je, Hwa Heon,Noh, Sora,Hong, Sung-Gil,Ju, Youngjun,Kim, Jungbae,Hwang, Dong Soo Elsevier 2017 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.323 No.-
<P><B>Abstract</B></P> <P>Cellulose nanofibers (CNFs) are one of attractive supporting materials for enzyme immobilization due to their unique properties such as high surface area, high porosity and surface carboxyl groups for chemical bonding. In this study, CNFs were prepared via TEMPO-mediated oxidation and physical grinding of cellulose, and further used for the immobilization of α-chymotrypsin (CT) enzyme via four different approaches such as covalent attachment (CA), enzyme coating (EC), enzyme precipitate coating (EPC), and magnetically-separable EPC (Mag-EPC). EPC approach consists of three steps: covalent enzyme attachment, enzyme precipitation and crosslinking, while EC represents a control without the step of enzyme precipitation. Amine-functionalized magnetic nanoparticles were added during the enzyme precipitation and crosslinking steps to produce magnetically-separable EPC. The activities of CA, EC, EPC and Mag-EPC were 0.067, 0.14, 1.3 and 2.6 units per mg CNFs, respectively, representing that the activity of Mag-EPC was 38-, 19- and 2-times higher than those of CA, EC and EPC, respectively. After incubation under shaking (200rpm) for 30days, CA, EC, EPC and Mag-EPC maintained 12%, 46%, 77% and 50% of their initial activities, respectively, while free CT showed only 0.2% of its initial activity even after 8days. Because CT is a tricky enzyme to stabilize due to its inactivation mechanism via autolysis, the present results of stable EPC and Mag-EPC on CNFs have demonstrated the great potential of CNFs as an environmentally-friendly and economical carrier of enzyme immobilization, which allows for magnetic separation as well as high enzyme activity/loading and stability.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cellulose nanofibers (CNFs) were used as a carrier of chymotrypsin (CT) immobilization. </LI> <LI> Four different CT immobilization approaches on CNFs were performed. </LI> <LI> CT, a tricky enzyme to stabilize, was stably and massively immobilized on CNFs. </LI> <LI> Magnetic separation of enzyme precipitate coating on CNFs was effective. </LI> <LI> Potential of CNFs for stable and recyclable enzyme immobilization was demonstrated. </LI> </UL> </P>
김제민(Je-Min Kim),권순현(Sun-Heon Kwon),최정화(Jung-Hwa Choi),박영택(Young-Tack Park) 한국정보과학회 2008 한국정보과학회 학술발표논문집 Vol.35 No.1
온톨로지가 대용량화됨에 따라, 구축 과정에 많은 인력이 투입되고, 그 과정 역시 복잡해지고 있다. 따라서 온톨로지 구축과정에서 발생하는 여러 가지 논리적 오류를 찾아내어 수정하는 작업은 중요하다. 또한 온톨로지 기반의 검색이나 온톨로지들을 통합할 때 온톨로지를 구성하는 개념간의 관계를 추론하는 것 역시 매우 중요하다. 본 연구의 목표는 온톨로지 구축 시 논리적 오류를 갖는 개념들을 찾아주고, 개념들 간에 관계를 추론하는 엔진을 구축하는 것이다. 본 논문에서 제안하는 Minerva는 OWL로 작성한 온톨로지 중 논리적 오류를 갖는 개념들을 찾아내어, 온톨로지 개발자들이 효과적으로 온톨로지를 구축하는 것과, 개념간의 관계를 추론해 줌으로써 온톨로지 기반의 서비스 어플리케이션 구축에 도움을 준다.
안구 돌출증을 동반한 만성 경막외 혈종 : 증례보고 Case Report
김도헌,황용순,조을제,문재곤,김한규,이화동 대한신경외과학회 1996 Journal of Korean neurosurgical society Vol.25 No.8
A case of chronic epidural hematoma in the left frontal region is presented. The patient presented with a unique neurologic sign, exophthalmos, which was not a result of the injury but of in-growth of granulation tissue of the hematoma capsule into the orbit through the orbital roof defect. The time interval between head injury and the operation was about 25 years. Our case represent the second most longest time interval among the reviewed literatures.
600W급 IPMSM의 형상 변경에 따른 온도 특성 해석 및 분석
고덕화(Duk-Hwa Go),박제헌(Je-Heon Park),박병준(Byung-Jun Park),김규탁(Gyu-Tak Kim) 대한전기학회 2018 대한전기학회 학술대회 논문집 Vol.2018 No.-
본 논문에서는 IPMSM(Interior permanent magnet synchronuos motor)의 효율 및 온도 특성 향상 설계를 수행하였다. 고정자 형상 변경을 통하여 자속 포화도 개선을 수행하였으며, 권선 사양 변경을 통한 동손 저감을 수행하였다. 전동기 특성 해석은 FEA를 이용하였으며, 집중정수법인열 등가회로망법을 적용하여 온도 특성 해석을 수행하였다. 이에 설계된 전동기에 대한 실험을 통한 검증을 수행하였다.
Effects and Optimization of Selection Pressure in Enzyme Production Using Recombinant E .
Park, Kwan Hwa,YOO, YOUNG JE,Lee, Jung Heon 한국화학공학회 1991 NICE Vol.9 No.3
Selection pressure is widely used in stabilizing the plasmid of the recombinant microorganism. The effects of selection pressure on enzyme production were investigated using recombinant E. coli harboring plasmid pTA322. Optimum ampicillin concentration. which maximizes the enzyme production was 150 pg /ml in flask culture and 50 pg/ml in the culture using 2-1 fermentor. Optimum concentration or selection pressure in a stirred fermentor was different from that in a flask due to different agitation effects. It was found from mathematical modelling that as the concentration of ampicitlin increased, the plasmid-harboring cells with low plasmid copy number were damaged severely, while the specific production rate increased due to the high plasmid copy number in flue microorganism.