• Membrane Journal
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• v.23 no.2
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• pp.144-150
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• 2013

In order to increase the permeabilities of $N_2$, $O_2$, $CH_4$, $CO_2$, $SO_2$, Poly (ether block amides) (PEBAX) 3533 and its blended membranes with Poly (ethylene glycol) (PEG) of molecular weight 400 were prepared. The contents of PEG400 were 20%, 40%, and 50% and this membranes were characterized in terms of permeability for $N_2$, $O_2$, $CH_4$, $CO_2$, $SO_2$ gases and also diffusivity and solubility as well by using the time-lag gas separation apparatus. As expected, the permeabilities incerased as the contents of PEG400 increased. For the ideal selectivity, there is no big difference in values of between PEBAX 3533 and PEBAX/PEG400 membranes. The increase of permeabilities is due to the increases of solubilities of gases in question and this will be explained in more detail.

• Journal of the East Asian Society of Dietary Life
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• v.24 no.6
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• pp.739-747
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• 2014

The aim of the study was to determine the effects of Ixeris dentata extract (IDE) on anticancer activity in human breast cancer MDA-MB-231 cells at both cellular and molecular levels. The cells were cultured in the presence of 0, 20, 30 and $40{\mu}g/mL$ Ixeris dentata extract for 24 hours, respectively. At the end of culture, cytochemical analyses for MTT activity, trypan blue dye exclusion, Annexin V-FITC Apoptosis, and radical oxygen species (ROS) were conducted. RT-PCR was also performed to determine whether or not alterations in cell viability affect the Bax/Bcl-2 ratio. MTT assay showed that relative cell viability decreased in a dose-dependent manner (p<0.05). Reduction of cell viability matched well with increased cell membrane permeability as determined by trypan blue dye exclusion test (p<0.05). The rates of intracellular ROS also increased in a similar manner to those of TB-stained cells. There was an associated shift of apoptotic cells from early to late apoptosis between the 30 and $40{\mu}g/mL$. Bax/Bcl-2 ratio significantly increased along with significant decreases in Bcl-2 expression between 30 and $40{\mu}g/mL$ groups (p<0.05). In conclusion, anticancer activity of Ixeris dentata extract is modulated by a reduction in cell viability along with increased membrane permeability, leading to ROS accumulation within cells, and subsequently cell death through an apoptotic pathway that involves Bax and Bcl-2 in human breast cancer MDA-MB-231 cells.

• Korean Journal of Metals and Materials
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• v.48 no.6
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• pp.523-532
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• 2010

Co-application of organic coating and cathodic protection has not provided enough durability to low-alloyed steels inseawater ballast tank (SBT) environments. An attempt has made to study the effect of alloy elements (Al, Cr, Cu, Mo, Ni, Si, W) on general and localized corrosion resistance of steels as basic research to develop new low-allowed steels resistive to corrosion in SBT environments. For this study, we measured the corrosion rate by the weigh loss method after periodic immersion in synthetic seawater at $60^{\circ}C$, evaluated the localized corrosion resistance by an immersion test in concentrated chloride solution with the critical pH depending on the alloy element (Fe, Cr, Al, Ni), determined the permeability of chloride ion across the rust layer by measuring the membrane potential, and finally, we analyzed the rust layer by EPMA mapping and compared the result with the E-pH diagram calculated in the study. The immersion test of up to 55 days in the synthetic seawater showed that chromium, aluminium, and nickel are beneficial but the other elements are detrimental to corrosion resistance. Among the beneficial elements, chromium and aluminium effectively decreased the corrosion rate of the steels during the initial immersion, while nickel effectively decreased the corrosion rate in a longer than 30-day immersion. The low corrosion rate of Cr- or Al-alloyed steel in the initial period was due to the formation of $Cr_2FeO_4$ or $Al_2FeO_4$, respectively -the predicted oxide in the E-pH diagram- which is known as a more protective oxide than $Fe_3O_4$. The increased corrosion rate of Cr-alloyed steels with alonger than 30-day exposure was due to low localized corrosion resistance, which is explained bythe effect of the alloying element on a critical pH. In the meantime, the low corrosion rate of Ni-alloyed steel with a longer than 30-day exposure wasdue to an Ni enriched layer containing $Fe_2NiO_4$, the predicted oxide in the E-pH diagram. Finally, the measurement of the membrane potential depending on the alloying element showed that a lower permeability of chloride ion does not always result in higher corrosion resistance in seawater.

• The Korea Journal of Herbology
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• v.32 no.2
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• pp.87-95
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• 2017

Objectives : Infectious diseases by Methicillin-Resistant Staphylococcus aureus (MRSA) are a growing problem worldwide. Characteristic of MRSA is endlessly mutation to resist antibiotics. Daehwanggo (DHG) is one of the oriental medicine prescriptions contained in Principles and Practice of Eastern Medicine. Daehwanggo was mainly used for external preparation from old times. The purpose of this study is to confirm possibility as supplementary drug of DHG about antibiotics through observation of synergy effect between DHG and commercial antibiotics and to observe restriction on growth of MRSA on any pathway through observation of mechanism. Methods : The minimum inhibitory concentration (MIC) of DHG against MRSA is $500{\sim}2000{\mu}g/m{\ell}$ by broth dilution method. In the checkerboard method, the combinations of DHG with antibiotics has partial synergistic effect or synergy effect and DHG markedly reduced the MICs of the antibiotics oxacillin (OX), gentamicin (GT) against MRSA. In the inhibition of resistance mechanism of DHG against MRSA, the expression of resistance gene and protein about ${\beta}-lactam$ antibiotic was reduced. Also, we observed the effect of DHG about cell membrane permeability against MRSA, and confirmed that DHG suppressed growth of strains by increasing cell membrane permeability. Results : Basis on the result, we speculate that DHG increase antibacterial activity of antibiotics against MRSA by changing the structure of cell wall of MRSA. Conclusions : These data suggest that Daehwanggo possesses possibility as supplementary drug about antibiotics against MRSA.

• Journal of the Korean Applied Science and Technology
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• v.29 no.3
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• pp.478-485
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• 2012

Polymers are widely used as membrane material for performing the separation of various gaseous mixtures due to their attractive permselective properties and high processability. The separation characteristics of $CH_4$ and $CO_2$ mixed gas using polyamide composite membrane has been studied in this work. The sample gas was prepared by mixing pure methane and carbon dioxide. Permeation tests were carried out at different operation conditions. Feed flow rates were varied between 800~1000 $cm^3/min$, and the stage cuts were varied between 50~60%. The gas inlet pressure and the temperature were varied as 6 bar and $30{\sim}70^{\circ}C$, respectively. The effects of the above mentioned parameters were investigated to estimate the permeability of $CH_4$ and $CO_2$, and the selectivity of $CO_2$ was also calculated for all conditions. The Arrhenius plots were also performed to obtaine the activation energies of $CH_4$ and $CO_2$ permeabilities.

• Membrane Journal
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• v.13 no.4
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• pp.246-256
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• 2003

For the olefin recovery from polyolefin off-gas, the permeation behaviors of olefins and nitrogen were investigated through three kinds of PDMS membranes - cross-linked PDMS membranes, a polysiloxaneimide membrane, and oligo-PDMS modified PDMS membranes. Their pure gas permeabilities were measured as a function of operation temperature(-20 to $50^{\circ}C$) and pressure(1 to 25 atm) with ethylene($C_2\;H_4$), propylene($C_3\;H_6$), butylene($C_4\;H_8$), and nitrogen($N_2$) gases. The permeabilities of olefins and nitrogen highly depended upon the nature of PDMS membranes. Among these membranes, cross-linked PDMS membranes showed stable and high olefin/nitrogen selectivities over a wide operation pressure range and further study in various test conditions. Their permeability of olefin and nitrogen were governed by the condensation temperature(solubility selectivity) and plasticization, not the order of the size(diffusivity selectivity) of gases, which matched well with the general permeation behavior of rubbery polymeric membranes for condensable and non-condensable gases. With increasing feed pressure or decreasing feed temperature, the permeabilities of more condensible olefins increase highly, presumably due to high solubility and plasticization, but that of non-condensible nitrogen decreases slightly and thus, the selectivities of olefin/nitrogen increase highly.

• Membrane Journal
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• v.18 no.4
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• pp.282-293
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• 2008

Partially sulfonated poly(aryl ether sulfone) membranes were prepared from the sulfonated sulfone monomer, which was synthesized by a nucleophilic substitution, non-sulfonated monomers and potassium carbonate by a direct polymerization method and a subsequent solution casting technique with mixed solvents of N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc). To investigate the effect of mixed solvent, the volume ratios of NMP and DMAc were varied in the range of $0{\sim}100%$ and the degrees of sulfonation of the copolymers were fixed as 50%. The surface properties of the resulting membranes were examined by scanning electron microscope (SEM) and atomic force microscope (AFM), and a comparative study of the morphology changes and the physicochemical properties such as proton conductivity and methanol permeability was achieved. It was found that proton conductivities depend on the volume ratio of NMP-DMAc mixed solvents, and the proton conductivity determined at the condition of $25^{\circ}C$ and 100% relative humidity was $1.38{\times}10^{-1}\;S/cm$ for the membrane prepared in the 50:50 v/v-% of NMP : DMAc mixed solvent.

• Journal of the Korean Ceramic Society
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• v.42 no.3 s.274
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• pp.165-170
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• 2005

Sol-gel methods offer many advantages over conventional slip-casting, including the ability to produce ceramic membranes. They are purer, more homogeneous, more reactive and contain a wider variety of compositions. We produced ormosil sol using sol-gel process under various molecular weight of polymer species[polyethylene glycol(PEG)] in total system [Tetraethyl ortho silicate(TEOS)-polyethylene glycol(PEG)]. The properties of as-prepared ormosil sol such as viscosity and gelation time are characterized. Also, the ceramic membrane was prepared by dip-coating with synthetic sol and its microstructure was observed by scanning electron microscopy. The permeability and rejection efficiency of membrane for oil/water emulsion were evaluated as cross­flow apparatus. The ormosil sol coated membrane was easily formed by steric effect of polymer and it improved flux efficiency because infiltration into porous support decreased. Its flux efficiency was elevated about $200\;l/m^2h$ compared with colloidal sol coated membrane at point of five minutes from starting test.

• Membrane Journal
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• v.18 no.1
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• pp.65-74
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• 2008

NOM and fine particles are the main target materials in water treatment using membranes. Particularly, humic substances extracted from soils are frequently used in many fundamental studies representing natural organic matter in raw water for drinking water treatment. In this study, ultrafiltration (UF) of artificial humic water and natural river water was conducted and the characteristics of removal efficiency and permeability were compared. In the UF of river water, the transmembrane pressure increased in the same pattern with that of 5 mg/L humic water. For the removal of organic matter and fine particles, however, two types of feed water had shown different trends. Kaolin particles and humic acids added to artificial water were better removed, while colloids and organics in natural water were relatively poorly removed. From the $UV_{254}$ and GPC analyses, it seemed that the hydrophobicity and size of humic substances contributed to the greater removal of organic matter. The UF membrane applied for humic water also showed a higher flux recovery by caustic chemical cleaning than that for river water.

• Membrane Journal
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• v.28 no.4
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• pp.221-232
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• 2018

The silica containing carbon ($C-SiO_2$) membranes were fabricated using poly(imide siloxane)(Si-PI) and polyvinylpyrrolidone (PVP) blended polymer. The characteristics of porous carbon structures prepared by the pyrolysis of polymer blends were related with the micro-phase separation behaviors of the two polymers. The glass transition temperatures ($T_g$) of the mixed polymer blends of Si-PI and PVP were observed with a single $T_g$ using differential scanning calorimetry. Furthermore, the nitrogen adsorption isotherms of the $C-SiO_2$ membranes were investigated to define the characteristics of porous carbon structures. The $C-SiO_2$ membranes derived from Si-PI/PVP showed the type IV isotherm and possessed the hysteresis loop, which was associated with the mesoporous carbon structures. For the molecular sieving probe, the $C-SiO_2$ membranes were prepared with the ratio of Si-PI/PVP and the pyrolysis conditions, such as the pyrolysis temperature and the isothermal times. Consequently, the $C-SiO_2$ membranes prepared by the pyrolysis of Si-PI/PVP at $550^{\circ}C$ with the isothermal time of 120 min showed the $O_2$ permeability of 820 Barrer ($1{\times}10^{-10}cm^3(STP)cm/cm^2{\cdot}s{\cdot}cmHg$) and $O_2/N_2$ selectivity of 14.