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미세표면분석 기법을 이용한 미용 콘택트렌즈와 일반 콘택트렌즈의 표면거칠기와 세균부착성 비교
지용우,홍순호,정동룡,김응권,이형근,Yong Woo Ji,Soon Ho Hong,Dong Yong Chung,Eung Kweon Kim,Hyung Keun Lee 대한안과학회 2014 대한안과학회지 Vol.55 No.5
Purpose: To determine the surface roughness of cosmetic and conventional contact lenses (CLs) and their susceptibility to bacterial adhesion. Methods: Concave surface roughness of cosmetic and conventional hydrogel (Etafilcon A) CLs was measured by atomic force microscopy (AFM) and scanning electron microscopy (SEM). In particular, the surface of the color tinted area of cosmetic CLs was measured. CLs were immersed into a bacterial solution of Pseudomonas aeruginosa for 1, 12, or 24 hours and culture of P. aeruginosa that had adhered to the CLs was performed. Results: Concave surface roughness of cosmetic CLs significantly increased compared with conventional CLs by AFM (<em>p</em> < 0.05). Bacterial colony formation of <em>P. aeruginosa</em> adhering to cosmetic CLs within one hour significantly increased compared with conventional CLs (<em>p</em> = 0.047). Adhesions of <em>P. aeruginosa</em> to CLs within one hour was found to correlate significantly with the surface roughness of CL (r > 0.9, <em>p</em> < 0.05). By SEM, <em>P. aeruginosa</em> had adhered to the color-tinted area more than to the non-color-tinted area of cosmetic CLs. Conclusions: Surface of cosmetic CLs was significantly rougher and initial adhesion of bacteria was higher to cosmetic CLs than to conventional CLs. In particular, an increased number of bacteria was found to be adhered to the color-tinted area of cosmetic CLs. Initial bacterial adhesion is important because it is the first stage of bacterial attachment process to any surface. After then, the adherent bacteria can progress to form a biofilm. Increased surface roughness of CLs contributes to opportunities for the CL to come into contact with bacteria, and thus, initial bacterial adhesion increases. In this study, it is clear that cosmetic CLs are more vulnerable to bacterial adhesion. To avoid serious complications, such as bacterial keratitis, the manufacturing process for smoothing and treating the surface in order to inhibit bacterial adhesion should be developed in the future. J Korean Ophthalmol Soc 2014;55(5):646-655
Irisappan Ganesh,홍순호,SAMBANDAM RAVIKUMAR,박시재,Seung Hwan Lee 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.7
The malate-pyruvate conversion pathway is catalyzed by two malic enzyme isomers, MaeA and MaeB. qRT-PCR was carried out under malate and pyruvate supplemented conditions to understand the dynamics of maeA and maeB gene expression. maeA expression was elevated by malate, and maeB expression was inhibited by levels of both malate and pyruvate higher than 0.1 mM. Green fluorescent protein (GFP) reporter plasmids were also constructed by integration of the maeA/maeB promoter with the gfp gene. We showed that maeA driven GFP expression was positively and negatively correlated with extracellular malate and pyruvate induction. In contrast, no significant changes in maeB driven GFP expression were observed under both malate and pyruvate supplemented conditions.
유익근,Won Sik Lee,홍순호,정진석,류근갑 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.4
A single submerged membrane bioreactor (MBR) for nitrification of ammonium and a pre-denitrification MBR process for total nitrogen (TN) removal were investigated in comparison. A single nitrifying MBR was fed with syntheticammonium wastewater of up to 900 mgN/l without organics so that the MBR was maintained as a pure nitrifying system. A high nitrifying capacity around 1.8 kgNH4-N/m3/day was achieved while keeping the ammonium oxidation rate above 98%. Sludge volume index (SVI) gradually decreased down to less than 50 indicating good settleability of nitrifying sludge. The increase of suction pressure was less than 5 cm Hg over 7-months of operation. TN removal efficiency was determined in a pre-denitrification configuration with an anoxic reactor. Synthetic wastewater of 1200 mgCOD/l and 200 mgN/l was fed to the system at loads of 2.4 kgCOD/m3/day and 0.4 kgN/m3/day, respectively. As the internal recycle ratio from aerobic to anoxic zone increased from 2 to 6, TN removal efficiency was enhanced from 70 9 to 89 3%. With the sludge concentration of around 12,000 mg/l, SVI was highly fluctuated from 60 to 350 indicating the partial deterioration of sludge settleability. The suction pressure after 8 months of operation increased to above 10 cm Hg which is higher than that in a single nitrifying MBR. The concentration of extracellular polymeric substances (EPS), especially for carbohydrate content, was higher in the operation of a pre-denitrification MBR process than in a single nitrifying MBR. It is likely that the sludge characteristic such as settleability is related with membrane fouling but, further extensive study is needed. The performance of a pre-denitrification MBR process was also verified with real petrochemical nitrogen wastewater.