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장지환,최권영 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Yarrowia lipolytica is well known for fatty acids and fatty alkanes biotransformation. it has 12 kinds of Alk monooxygenase enzymes and some are known to be responsible for fatty alkane ω-oxidation. Oxyfunctionalization of fatty alkanes, especially at ω-position, generates very interesting oxidative metabolites which could be converted further into various biopolymer monomers such as polyamide. One of the most important oxidation enzymes is alcohol dehydrogenase enzymes (ADHs) which could convert ω-hydroxyfatty acids into ω -oxofatty acids. However, not much information about Y. lipolytica ADHs were not elucidated. Thus, in this study, we cloned and expressed Y. lipolytica ADHs in E. coli. In order to solubilize the ADH enzymes, several optimization strategies like inducer concentrations, co-expression with molecular chaperones were investigated. The E. coli cells which expressed Y. lipolitica ADH could produce dodecanal up to 37.27 mg/L in whole cell biotransformation of dodecanol.
장지환,최권영 한국생물공학회 2021 Biotechnology and Bioprocess Engineering Vol.26 No.2
In this study, alcohol dehydrogenases (ADH) enzymes from Yarrowia lipolytica were investigated for the cloning, soluble expression, and biotransformation of 1-dodecanol to 1-dodecanal, which reaction was thermodynamically unfavorable. Sole expression of ADHs in Escherichia coli did not produce soluble form of cytosolic protein, in spite of the effort to solubilize ADH protein by optimizing IPTG concentration, temperature, and auto-induction medium. Eventually, the active form of soluble ADH proteins was successfully obtained through the co-expression of ADH with chaperone protein in pG-KJE8 vector. After analyzing the individual sets of optimization, it was determined that pET-28a(+)::adh coexpression with the pG-KJE8 molecular chaperone in LB medium with 0.1 mM IPTG, 4 mg/mL arabinose, and 2 ng/mL tetracycline achieved optimum expressions against all of the five ADH proteins. Finally, the whole cell biotransformation activity of ADH2 was determined in 1-dodecanol oxidation to 1-dodecanal, followed by further oxidation to 1-dodecanoic acid.
Predictors of 30-day Mortality and 90-day Functional Recovery after Primary Pontine Hemorrhage
장지환,송윤규,김영준 대한의학회 2011 Journal of Korean medical science Vol.26 No.1
The factors related to death and functional recovery after primary pontine hemorrhage (PPH) in Koreans has not been well defined. The authors sought to identify independent predictors of death and functional recovery after PPH using data obtained at a single institute. Data were collected retrospectively on 281 patients with PPH admitted to the Stroke Unit at our hospital between January 1, 2000 and December 31, 2009. Multivariate logistic regression analysis was used to evaluate the associations between selected variables and 30-day mortality and 90-day functional recovery after PPH. One-hundred and ten patients (39.1%) died within 30 days of PPH and 27 patients (9.6%) achieved functional recovery within 90 days. By multivariate analysis, unconsciousness, dilated pupils,abnormal respiration, systolic blood pressure < 100 mmHg, hydrocephalus, and conservative treatment were found to be predictors of 30-day mortality, whereas consciousness, intact motor function, no history of hypertension or diabetes mellitus,intact eye movement, a hematoma volume of < 5 mL, no ventricular hemorrhage, and normally sized ventricle were found to be predictors of 90-day functional recovery. The present findings suggest that systolic hypotension of less than 100 mmHg may predict 30-day mortality and a history of underlying hypertension and diabetes mellitus may predict 90-day functional recovery.
CFD 를 이용한 CMP 의 Groove Sizing 최적화
장지환(Jihwan Jang),이도형(Dohyung Lee) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
In this paper, slurry fluid motion, abrasive particle motion, and effects of groove sizing on the pads are numerically investigated in the 2D geometry. Groove depth is optimized in order to maximized the abrasive effect. The simulation results are analyzed in terms of shear stress on pad, groove and wafer, streamline and velocity vector. The change of groove depth entails vortex pattern change, and consequently affects material removal rate. Numerical analysis is very helpful for disclosing polishing mechanism and local physics.