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Kim, Sang Gon,Park, Si Young,Chun, Jeong Hwan,Chun, Byung-Hee,Kim, Sung Hyun Balaban Publishers 2012 Desalination and Water Treatment Vol.43 No.1
<P> Sulfonated poly(arylene ether sulfone) containing sulfonic acid and amino groups (SDADPS) were successfully synthesized using direct-step polymerization as a novel thin-film composite (TFC) reverse osmosis (RO) membrane material for high chlorine resistance. TFC membranes were prepared using an interfacial polymerization (IP) reaction with trimesoyl chloride (TMC) and amine solution, containing m-phenylenediamine (MPDA) and SDADPS, on a polysulfone (PS) ultrafiltration (UF) support membrane. The synthesized SDADPS and fabricated TFC RO membranes were characterized by nuclear magnetic resonance spectroscopy and scanning electron microscope. Moreover, RO performances, salt rejection and water flux, were measured using a cross-flow cell instrument. Chlorine resistance was evaluated using sodium hypochlorite solution. The membrane fabricated with SDADPS was compared with a typical polyamide (PA) TFC membrane which was prepared by IP reaction with TMC and MPDA on a PS support membrane. The SDADPS RO membrane had much higher chlorine resistance than PA RO membrane and showed good RO performances, such as water flux (32L/m<SUP>2</SUP>h) and salt rejection (95%). </P>
Kim, Si Gon,Yang, Jong Yeun,Kim, Do Wan,Lee, Yeon Ju The Korean Pain Society 2013 The Korean Journal of Pain Vol.26 No.2
There have been reports of abnormalities in the lumbosacral region involving a lower-than-normal termination of the dural sac, which is caused by disease or anatomical variation. Inadvertent dural puncture or other unexpected complications can occur during caudal epidural block or adhesiolysis in patients with these variations, but only a small number of case reports have described this issue. We report a case of dural puncture by the introducer needle before attempting caudal epidural adhesiolysis, which occurred even though the needle was not advanced upward after penetrating the sacrococcygeal ligament. Dural puncture was caused by a morphological abnormality in the lumbosacral region, with no pathological condition; the dural sac terminal was located more distally than normal. However, dural puncture could have been prevented if we had checked for such an abnormality in the magnetic resonance imaging (MRI) taken before the procedure.
Optimization of Lab Scale Methanol Production by Methylosinus trichosporium OB3b
Kim, Hee-Gon,Han, Gui-Hwan,Kim, Si-Wouk 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.3
Methylosinus trichosporium OB3b is a methanotrophic bacterium containing particulate methane monooxygenase (MMO), which catalyzes the hydroxylation of methane to methanol. The methanol is further oxidized to formaldehyde by methanol dehydrogenase (MDH). We developed a novel compulsory circulation diffusion system for cell cultivation. A methane/air mixture (1:1, v/v) was prepared in a tightly sealed gas reservoir and pumped into a nitrate mineral salt culture medium under optimal conditions (5 ${\mu}M$ $CuSO_4$, pH 7.0, $30^{\circ}C$). Cells were harvested, washed, and resuspended (0.6 mg dry cells/mL) in a 500 mL flask in 100 mL of 10 mM phosphate buffer (pH 7.0) containing 100 mM NaCl and 1 mM EDTA as MDH inhibitors, and 20 mM sodium formate. A single 12 h batch reaction at $25^{\circ}C$ yielded a final concentration of 13.2 mM methanol. The use of a repeated batch mode, in which the accumulated methanol was removed after each of three 8 h cycles over a 24 h period, showed a productivity of 2.17 ${\mu}mol$ methanol/h/mg dry cell wt. Finally, a lab-scale reaction performed using a 3 L cylindrical reactor with a working volume of 1 L produced 13.7 mM methanol after 16 h. Our results identify a simple process for improving the productivity of biologically derived methanol and, therefore the utility of methane as an energy source.
Kim, Hee-Gon,Kim, Si-Wouk The Korean Society for Biotechnology and Bioengine 2006 Biotechnology and Bioprocess Engineering Vol.11 No.2
Methanotrophs are microorganisms that possess the unique ability to utilize methane as their sole source of carbon and energy. A novel culture system, known as the compulsory circulation diffusion system, was developed for rapid growth of methanotrophic bacteria. Methanol dehydrogenase (MDH, EC 1.1.99.8) from Methylomicrobium sp. HG-1, which belongs to the type I group of methanotrophic bacteria, can catalyze the oxidation of methanol directly into formaldehyde. This enzyme was purified 8-fold to electrophoretic homogeneity by means of a 4 step procedure and was found in the soluble fraction. The relative molecular weight of the native enzyme was estimated by gel filtration to be 120 kDa. The enzyme consisted of two identical dimers which, in turn, consisted of large and small subunits in an ${\alpha}_2{\beta}_2$ conformation. The isoelectric point was 5.4. The enzymatic activity of purified MDH was optimum at pH 9.0 and $60^{\circ}C$, and remained stable at that temperature for 20 min. MDH was able to oxidize primary alcohols from methanol to octanol and formaldehyde.
Kim, Hee-Gon,Kim, Yan,Lim, Heon-Man,Shin, Hyun-Jae,Kim, Si-Wouk The Korean Society for Biotechnology and Bioengine 2006 Biotechnology and Bioprocess Engineering Vol.11 No.4
Trimethylamine dehydrogenase (TMADH, EC 1.5.99.7), an iron-sulfur flavoprotein that catalyzes the oxidative demethylation of trimethylamine to form dimethylamine and formaldehyde, was purified from Methylophaga sp. strain SK1. The active TMADH was purified 12.3-fold through three purification steps. The optimal pH and temperature for enzyme activity was determined to be 8.5 and $55^{\circ}C$, respectively. The $V_{max}\;and\;K_m$ values were 7.9 nmol/min/mg protein and 1.5 mM. A genomic DNA of 2,983 bp from Methylophaga sp. strain SK1 was cloned, and DNA sequencing revealed the open reading frame (ORF) of the gene coding for TMADH. The ORF contained 728 amino acids with extensive identity (82%) to that of Methylophilus methylotrophus $W_3A_1$.
Characterization of Methylophaga sp. strain SK1 Cytochrome $c_L$ Expressed in Escherichia coli
Kim, Hee-Gon,Phan, Trongnhat,Jang, Tae-Sa,Koh, Moon-Joo,Kim, Si-Wouk The Microbiological Society of Korea 2005 The journal of microbiology Vol.43 No.6
Methylophaga sp. strain SK1 is a new restricted facultative methanol-oxidizing bacterium that was isolated from seawater. The aim of this study was to characterize the electron carriers involved in the methanol oxidation process in Methylophaga sp. strain SK1. The gene encoding cytochrome $c_L$ (mxaG) was cloned and the recombinant gene was expressed in Escherichia coli $DH5\alpha$ under strict anaerobic conditions. The recombinant cytochrome $c_L$ had the same molecular weight and absorption spectra as the wild-type cytochrome $c_L$ both in the reduced and oxidized forms. The electron flow rate from methanol dehydrogenase (MDH) to the recombinant cytochrome $c_L$ was similar to that from MDH to the wild-type cytochrome $c_L$. These results suggest that recombinant cytochrome $c_L$ acts as a physiological primary electron acceptor for MDH.