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(PIM-co-Ellagic Acid)-기반의 이산화탄소 분리막의 개발
호세인 이크발,허스너 아스몰,김동영,김태현 한국막학회 2020 멤브레인 Vol.30 No.6
(PIM-1)과 ellagic acid로 만든 랜덤형 공중합체가 간단한 방법으로 합성되었으며, 이산화탄소 분리막에 대한 적용 가능성에 대해서 연구하였다. 이 공중합체의 경우 PIM (polymers with intrinsic microporosity) 고분자의 미세 기공 구조에 기 인한 높은 기체 투과도와 평면 구조와 친수성을 갖는 ellagic acid에 기인한 높은 이산화탄소에 대한 선택성에 의해 우수한 이 산화탄소 기체 분리 성능을 나타내었다. 즉, 이산화탄소에 대한 투과도 4516 Barrer와 CO2/N2 (> 23~26) 및 CO2/CH4 (> 18~19)의 높은 선택성으로 두 쌍의 가스 혼합물에 대해 Robeson 상한(2008)을 초과한 결과를 나타내었다. 이와 같이 PIM-1 에 평면구조를 갖는 ellagic acid을 혼입하면 PIM-1의 꼬인 구조를 방해하여 기체 투과성을 향상 시킬 뿐만 아니라 공중합체 의 강성과 극성이 증가하여 N2 및 CH4에 대한 CO2의 선택성을 증가시키는 결과를 확인하였다. Random copolymers made of both ‘polymer of intrinsic microporosity (PIM-1)’ and Ellagic acid were prepared for the first time by a facile one-step polycondensation reaction. By combining the highly porous and contorted structure of PIM (polymers with intrinsic microporosity) and flat-type hydrophilic ellagic acid, the membranes obtained from these random copolymers [(PIM-co-EA)-x] showed high CO2 permeability (> 4516 Barrer) with high CO2/N2 (> 23~26) and CO2/CH4 (> 18~19) selectivity, that surpassed the Robeson upper bound (2008) for both pairs of the gas mixture. Incorporation of flat-type ellagic acid into the PIM-1 not only enhances the gas permeability by disturbing the kinked structure of PIM-1 but also increases the selectivity of CO2 over N2 and CH4, due to an increase of rigidity and polarity in the resultant copolymer membranes.
Bisimidazolium-PEG으로 가교된 CO2 분리용 폴리이미드 고분자막
호세인 이쿠발,김태현 한국막학회 2016 한국막학회 총회 및 학술발표회 Vol.2016 No.05
A series of bisimidazolium-PEG mediated crosslinked polyimides with different PEG chain length have been prepared for gas separation membranes. The bisimidazolium-PEG was used both as crosslinkers and CO2-solubilizing groups. The crosslinked 6FDA-durene polyimide membranes prepared displayed excellent chemical, mechanical and thermal stabilities. Furthermore, high CO2/N2 and CO2/CH4 selectivity was obtained while keeping relatively high permeability. The preparation and the effect of the PEG chain length within the bisimidazolium-PEG groups on the structures and physicochemical properties of the polymers, as well as the gas separation properties of the corresponding membranes will be discussed.
사브리나 호세인,B.C.J. De Silva,S.H.M.P. Wimalasena,H.N.K.S. Pathirana,허강준 한국동물위생학회 2017 韓國家畜衛生學會誌 Vol.40 No.1
Salmonella enterica subsp. enterica is a common microbial flora in pet turtles, which could opportunisti-cally become pathogenic to human. Their possession of aminoglycoside resistance genes has important significance both in humans and animal medicine. In this study, twenty-one Salmonella enterica subsp. enterica were isolated from thirty-five individual turtles purchased from pet shops and online markets in Korea. In order to characterize the aminoglycoside susceptibility patterns, antimicrobial susceptibility tests were performed against gentamicin, amikacin and kanamycin of aminoglycoside antimicrobial group. Each of the isolates showed susceptibility to all tested aminoglycosides in disk diffusion and minimum inhibitory concentration (MIC) tests. PCR assay was carried out to determine aminoglycoside resistance genes, integron and integron mediated aminoglycoside genes. None of the isolates showed aac(3)-IIa, aac-(6′)-Ib, armA, aphAI-IAB aminoglycoside resistance genes. Only, five isolates (24%) har-bored class 1 integron related IntI1 integrase gene. The results suggest that Salmonella enterica subsp. enterica strains isolated from pet turtles are less resistance to aminoglycosides and don’t harbor any aminoglycosides resistance genes.
사브리나 호세인,허홍회,B.C.J. De Silva,S.H.M.P. Wimalasena,H.N.K.S. Pathirana,허강준 한국실험동물학회 2017 Laboratory Animal Research Vol.33 No.3
Pet turtles are well-known to harbor an array of bacterial pathogens which can cause zoonotic infections in humans as well as opportunistic infections in the turtles itself. Essential oils are the natural plant extracts which have been traditionally used for disease treatment. In the present study, the essential oil of lavender (EOL) was examined for its antibacterial activity against thirty-eight strains of turtle-borne pathogenic bacteria belonging to seven species; Aeromonas hydrophila, A. caviae, A. dhakensis, Citrobacter freundii, Proteus mirabilis, Salmonella enterica and Pseudomonas aeruginosa. Antibacterial activity of EOL was tested by means of disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) tests. In addition, the antimicrobial susceptibility pattern of 11 commonly used antimicrobials was examined and the multiple antibiotic resistance (MAR) index was calculated. The results revealed that EOL was active against all tested turtle-borne pathogenic bacteria except P. aeruginosa. The range of MIC and MBC values of EOL against isolates except P. aeruginosa were recorded as 0.5-1% (V/V) and 0.5-2% (V/V), respectively. The MBC/MIC ratio was detected as <4, revealing that the tested EOL was bactericidal. Besides, most of the isolates were resistant to different antimicrobials in antimicrobial disk diffusion test. MAR index values of the tested strains were ranging from 0.27 to 0.91. The outcomes indicate that EOL has a potential to be used as an antibacterial agent against pathogenic bacteria isolated from pet turtles.
Numerical Analysis of mixing performance with modified Tesla Structure
샤카왓 호세인,아매드 앤사리,김광용 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
In this study, mixing of fluids in a microchannel with modified tesla structure operating at wide range of Reynolds number from 0.0.5 to 40, has been investigated numerically using three dimension Navier-Srokes equations. Mixing in the channel has been analyzed with two working fluids. water and ethanol. Modified tesla structure produces transverse dispersion by using Coanda effect In the micromixer. one of the fluid streams is divided into two substreams and mixes with the main flow again at the exit of the testa unit. Mixing performance and pressure drop has been analyzed with two dimensionless design variables. i.e.. ratio of the diffuser gap to channel width θ(h/w) and ratio of the curved gap to the channel width Ф(s/w). Results reveal that mixing and pressure drop characteristics are very sensitive to the geometric. Results also reveal that. lower value of h/w and s/w or less constriction provides higher mixing performance as well as pressure drop. The sensitivity analysis represents that mixing is more sensitive s/w. than the h/w.