• Carbon letters
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• v.9 no.1
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• pp.23-27
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• 2008

The adsorption and reduction of Cr (VI) to Cr (III) by surface modified activated carbon (AC) in an aqueous solution was studied. The effects of surface modifications on the properties of the carbons were investigated by the analysis of specific surface area, carbon surface pH, acid/base surface values and functional groups. In order to understand the Cr(VI) adsorption and reduction ratio from Cr(VI) to Cr(III), the Cr adsorption capacity of AC was also measured and discussed by using inductively coupled plasma and UV spectrophotometer. The modifications bring about substantial variation in the chemical properties whereas the physical properties such as specific surface area, pore volume and pore size distribution nearly were not changed. Total Cr adsorption efficiency of as-received activated carbon (R-AC) and nitric acid treated activated carbon (N1-AC and N2-AC) were recorded on 98.2, 99.7 and 100%. Cr(III) reduction efficiency of R-AC increased largely from 0.4% to 28.3% compared to N1-AC and N2-AC.

• Microbiology and Biotechnology Letters
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• v.45 no.1
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• pp.51-56
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• 2017

Cellulosic biomass is a renewable source for biofuel production from non-edible biomass. An optimized pretreatment process is required for the efficient utilization of cellulosic biomass. Among various pretreatment processes, the use of ionic liquids has been reported recently. However, the residual ionic liquid after pretreatment acts as an inhibitor of microbial fermentation. Recently, we isolated mutant Saccharomyces cerevisiae strains resistant to the ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM][Ac]) by using a directed evolutionary approach. When 3% [EMIM][Ac] was added to a medium containing 80 g/l of glucose, mutants D452-B2 and D452-S3 produced 35.6 g/l and 36.3 g/l of ethanol, respectively, for 18 h while the parental strain (S. cerevisiae D452-2) produced 1.3 g/l of ethanol. Thus, these mutant S. cerevisiae strains might prove advantageous when ionic liquids are used for biofuel production from cellulosic biomass.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.1
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• pp.27-34
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• 2002

In this paper, characteristics of the ac and dc flashover voltage in the horizontal air gap of a needle-needle electrode system were investigated when the combustion flame was present near the high-voltage electrode. In order to examine the flashover phenomena and the corona inception voltages caused by flame we measured the voltage and current waveforms when the corona and the flashover was occurred. We also observed, as increasing the applied voltages, the deflection or fluctuation phenomena in the shape of flames caused by the corona wind and the coulomb's force. As the results of an experimental investigation, we found that the reduction of flashover voltages, in comparison with the no-flame case, are 62.7[%] for k=1.0, 34.2[%] for h=5[cm], 27.3[%] for h=7[cm] and 21.4[%] for h=9[cm] when ac voltage is applied.

• Journal of Pharmaceutical Investigation
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• v.26 no.2
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• pp.71-82
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• 1996

This study has been undertaken to evaluate hydrophobic cyclodextrin(CD) derivatives as a sustained release carrier of azidothymidine(AZT), AZT, which has potent activity against AIDS and AIDS-related complex as thymidine analogue, has been reported that it has significant toxicity and short half life. Therefore, it is necessary to design sustained release oral dosage form to avoid undesirable side effects attributable to an excessive plasma concentration and to reduce the frequency of administration of AZT. Inclusion complexes of AZT with $acetyl-{\beta}-cyclodextrin\;(AC{\beta}CD)$ and $triacetyl-{\beta}-cyclodextrin(TA{\beta}CD)$ were prepared by solvent evaporation method. Interactions of AZT with CD were investigated by Differential Scanning Calorimetry(DSC) and Infrared Spectrophotometry(IR). The decreasing order of water solubilities of AZT and AZT-CD inclusion complexes were as follows; $AZT\;(27.873{\pm}0.015,mg/ml)\;>\;AZT-AC{\beta}CD\;(3.377{\pm}0.003)\;>\;AZT-TA{\beta}CD\;(2.528{\pm}0.001)$. Partition coefficients of $AZT-AC{\beta}CD\;and;\AZT-TA{\beta}CD$ inclusion complexes were increased by 1.27-fold, 1.54-fold in pH 1.2 and 1.32-fold, 1.47-fold in pH 6.8 in comparison with that of AZT. The mean dissolution time (MDT, min) which represents the rapidity of dissolution rate of AZT, $AZT-AC{\beta}CD,\;AZT-TA{\beta}CD$ were 5.12, 14.02 and 19.38 min in pH 1.2 and 2.52, 15.19 and 18.19 min in pH 6.8. AZT was very rapidly and completely dissolved in pH 1.2 and pH 6.8 within 5 minutes. But AZT-CD inclusion complexes showed the sustained release pattern in comparison with AZT alone. The simultaneous in situ nasal and jejunal recirculation study to compare the intrinsic absorptivity and the property of absorption sites revealed that the absorption of $AZT-TA{\beta}CD\;(N:35.35{\pm}1.08%,\;J:27.47{\pm}1.18%)$ was more than that of $AZT\;(N:16.89{\pm}2.25%,\;J:15.86{\pm}2.33%)$. The above results suggest that $TA{\beta}CD$ which is a hydrophobic cyclodextrin may serve as sustained release carrier with absorption enhancing effect.

• Journal of Microbiology and Biotechnology
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• v.27 no.1
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• pp.92-100
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• 2017

Acetoin (AC) is a volatile platform compound with various potential industrial applications. AC contains two stereoisomeric forms: (3S)-AC and (3R)-AC. Optically pure AC is an important potential intermediate and widely used as a precursor to synthesize novel optically active materials. In this study, chiral (3R)-AC production from meso-2,3-butanediol (meso-2,3-BD) was obtained using recombinant Escherichia coli cells co-expressing meso-2,3-butanediol dehydrogenase (meso-2,3-BDH), NADH oxidase (NOX), and hemoglobin protein (VHB) from Serratia sp. T241, Lactobacillus brevis, and Vitreoscilla, respectively. The new biocatalyst of E. coli/pET-mbdh-nox-vgb was developed and the bioconversion conditions were optimized. Under the optimal conditions, 86.74 g/l of (3R)-AC with the productivity of 3.61 g/l/h and the stereoisomeric purity of 97.89% was achieved from 93.73 g/l meso-2,3-BD using the whole-cell biocatalyst. The yield and productivity were new records for (3R)-AC production. The results exhibit the industrial potential for (3R)-AC production via whole-cell biocatalysis.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.303-309
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• 2017

This study investigated the potential use of steel slag (SS) (0.5~2.0 g/200 mL) for the removal of phosphate from wastewater compared with activated carbon (AC) (3.0~6.0 g/200 mL). The adsorption equilibrium data were best represented by Langmuir isotherm and its calculated maximum adsorption capacity was 91 mg/g for SS, 27 mg/g for AC. The adsorption kinetics was found to follow the pseudo-second order kinetics model and its rate constant was $0.0232{\sim}0.1357g/mg{\cdot}min$ for SS, $0.0247{\sim}0.1221g/mg{\cdot}min$ for AC. The overall uptake for the SS and AC was maximum at pH 2. Therefore, it can be concluded that steel slag could play an effective role in reducing phosphate concentration compared with activated carbon.

• Journal of Microbiology and Biotechnology
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• v.27 no.1
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• pp.189-196
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• 2017

Kaposi's sarcoma-associated herpesvirus (KSHV) is associated with formation of Kaposi's sarcoma, multicentric Castleman's disease, and primary effusion lymphoma. Replication and transcription activator (RTA) genes are expressed upon reactivation of KSHV, which displays a biphasic life cycle consisting of latent and lytic replication phases. RTA protein expression results in KSHV genome amplification and successive viral lytic gene expression. Transcriptional activity of viral lytic genes is regulated through epigenetic modifications. In Raji cells latently infected with Epstein-Barr virus, various modifications, such as acetylation and methylation, have been identified at specific lysine residues in histone H4 during viral reactivation, supporting the theory that expression of specific lytic genes is controlled by histone modification processes. Data obtained from chromatin immunoprecipitation and quantitative real-time PCR analyses revealed alterations in the H4K8ac and H4K20me3 levels at lytic gene promoters during reactivation. Our results indicate that H4K20me3 is associated with the maintenance of latency, while H4K8ac contributes to KSHV reactivation in infected TREx BCBL-1 RTA cells.

• The Journal of Pediatrics of Korean Medicine
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• v.27 no.1
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• pp.69-81
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• 2013

Objectives In this study, effects of Macmundongtang (MMT) on ATP or TNF-${\alpha}$ or PMA or EGF induced MUC5AC mucin production and gene expression from human airway epithelial cells and the increase in airway epithelial mucosubstances of rats were investigated. Materials and Methods Confluent NCI-H292 cells were pretreated for 30min in the presence of MMT and treated with ATP ($200{\mu}M$) or PMA (10 ng/ml) or EGF (25 ng/ml) or TNF-${\alpha}$ (0.2 nM) for 24hrs, to assess the effect of MMT both on ATP- or PMA- or EGF- or TNF-${\alpha}$-induced MUC5AC mucin production using enzyme-linked immunosorbent assay (ELISA) and on gene expression by the same inducers using reverse transcription-polymerase chain reaction (RT-PCR). At the same time, hypersecretion of airway mucus was induced by exposure of rats to SO2 during 3 weeks. Effect of orally-administered MMT during 2 weeks on increase in airway epithelial mucosubstances from tracheal goblet cells of rats was assesed using histopathological analysis after staining the epithelial tissue with PAS-alcian blue. Possible cytotoxicity of MMT was assessed by investigating the potential damage of kidney and liver functions by measuring serum GOT/GPT activities and serum BUN concentration of rats and the body weight gain during experiment, after administering MMT orally. Results (1) MMT did not only inhibit but also increased MUC5AC mucin productions and expression levels of MUC5AC gene from NCI-H292 cells. (2) MMT did not decrease the amount of intraepithelial mucosubstances of trachea of rats. (3) MMT did not show renal and hepatic toxicities and did not affect body weight gain of rats during experiment. Conclusions The result from the present study suggests that MMT might normalize the production and gene expression of airway mucin observed in various respiratory diseases accompanied by yin-deficiency, without in vivo toxicity to liver and kidney functions after oral administration.

• Journal of the Korean Chemical Society
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• v.61 no.3
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• pp.89-96
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• 2017

This study proposed adsorption of Pb(II) ions from aqueous solution using activated carbon prepared from areca catechu shell (ACS AC) using Timphan Method. The effects of independent variables on adsorption kinetic and isotherm have been investigated by conducting experiments in batch mode at neutral pH. The structural characterization of adsorbent was done by FT-IR and SEM analysis. The Pb(II) adsorption was correlated very well with the pseudo second-order kinetic (PSOKM) and Langmuir isotherm models (LIM). Increasing NaOH mass for activation and adsorption temperature increased weakly all the parameters of adsorption kinetic and isotherm. The Pb(II) ions adsorption capacity of the ACS AC at 27 and $45^{\circ}C$ was 50.51 and 55.25 mg/g, respectively. Thermodynamic parameters were determined, and the results confirmed the Pb(II) ions adsorption should be endothermic and spontaneous process, and both physical and chemical adsorption should be taken place.

• Bulletin of the Korean Chemical Society
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• v.26 no.7
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• pp.1065-1070
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• 2005

$[Mn_{12}O_{12}(O_2CPh-4-SMe)_{16}(H_2O)_4]{\cdot}7CH_2Cl_2$ (1), a new single-molecule magnet complex has been successfully synthesized by substitution of acetate ligand of Mn12ac with 4-(methylthio)benzoic acid. Complex 1 crystallizes into triclinic P$\overline{1}$ with a = 18.321(3) $\AA$, b = 19.011(3) $\AA$, c = 27.230(4) $\AA$, $\alpha$ = 86.973(3)$^{\circ}$, $\beta$ = 76.919(3)$^{\circ}$, $\gamma$ = 87.613(3)$^{\circ}$, and Z = 2. In complex 1, one Mn(III) ion has an abnormal Jahn-Teller elongation axis oriented at an oxide ion. Complex 1 has two out-of-phase ac susceptibility peaks in the 2-4 K and 4-7 K regions. Effective anisotropy energy barrier and pre-exponential factor are $U_{eff}$ = 45.95 K, 1/$\tau$0 = 8.6 ${\times}\;10^9s^{-1}\;for\;{\chi}_M$'' peaks in the lower temperature region and $U_{eff}$ = 59.45 K, 1/$\tau_0$ = 2.2 ${\times}\;10^8\;s^{-1}$ for $\chi_M$'' peaks in the higher temperature region. The parameters of S = 10, g = 1.87, D = -0.40 $cm^{-1}$, and E = 0.00034 $cm^{-1}$ were obtained from the M/N${\mu}_B$ vs. H/T plot of complex 1.