• Korean Journal of Materials Research
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• v.13 no.4
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• pp.251-258
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• 2003

The effects of the salt and the precursor pH on the synthesizing behavior and the morphology of mullite have been studied. Two kinds of mullite precursor sols were prepared by the dissolution of two kinds of salt (aluminum nitrate enneahydrate, Al($NO_3$)$_3$ㆍ$9H_2$O; type I and aluminum sulfate 14∼18 water, (SO$Al_4$)$_3$$\cdot$$14∼18H_2$O; type II) into the mixture of colloidal silica sol, respectively. Precursor pH of the sols was controlled to the acidic (pH= 1.5∼2) and basic (pH= 8.5∼9) conditions. The co-products with nitrate and sulfate were completely eliminated at $500^{\circ}C$ and $850^{\circ}C$, respectively, which was confirmed by TG/DTA results. The synthesizing temperature of mullite phase was found to be above $1200^{\circ}C$ for pH= 1.5∼2 and above $1300^{\circ}C$ for pH= 8.5∼9 in type I. However, in type II, the synthesizing temperature of mullite was decreased to $850^{\circ}C$ for pH= 1.5∼2 and $1100^{\circ}C$ for pH= 8.5∼9. The grain size of the mullite synthesized at pH= 8.5∼9 was larger than that at pH= 1.5∼2 in overall heat-treated temperatures, showing smaller grain size in type II. Aspect ratio of the mullite grains was more increased at pH= 1.5∼2 than pH= 8.5∼9 in type I, showing similar aspect ratio at both pH conditions in type II. It was found that the synthesizing temperature and grain size were predominantly governed by the initial precursor pH and decomposition of the salt, with minor effect on the grain morphology.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.108-109
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• 2013

Mitochondria play key roles in the production of cell's energy. Their dominant function is the synthesis of adenosine 5'-triphosphate (ATP) from adenosine diphosphate (ADP) and phosphate (Pi) through the oxidative phosphorylation. Evaluation of drug-induced mitochondrial toxicity has become increasingly important since mitochondrial dysfunction has recently been implicated in numerous diseases including cancer and diabetes mellitus. Mitochondrial functions have been monitored via oxygen consumption, mitochondrial membrane potential, and more importantly via ATP synthesis since ATP synthesis is the most essential function of mitochondria. Various analytical methods have been employed to investigate ATP synthesis in mitochondria, including high performance liquid chromatography (HPLC), bioluminescence technique, and pH measurement. However, most of these methods are based on destructive analysis or indirect monitoring through the enzymatic reaction. Infrared absorption spectroscopy (IRAS) is one of the useful techniques for real-time, label-free, and direct monitoring of biological reactions [1,2]. However, the strong water absorption requires very short path length in the order of several micrometers. Transmission measurements with thin path length are not suitable for mitochondrial assays because solution handlings necessary for evaluating mitochondrial toxicity, such as rapid mixing of drugs and oxygen supply, are difficult in such a narrow space. On the other hand, IRAS in the multiple internal reflection (MIR) geometry provides an ideal optical configuration to combine solution handling and aqueous-phase measurement. We have recently reportedon a real-time monitoring of drug-induced necrotic and apoptotic cell death using MIR-IRAS [3,4]. Clear discrimination between viable and damaged cells has been demonstrated, showing a promise as a label-free and real-time detection for cell-based assays. In the present study, we have applied our MIR-IRAS system to mitochondria-based assays by monitoring ATP synthesis in isolated mitochondria from rat livers. Mitochondrial ATP synthesis and hydrolysis were in situ monitored with MIR-IRAS, while dissolved oxygen level and solution pH were simultaneously monitored with O2 and pH electrodes, respectively. It is demonstrated that ATP synthesis and hydrolysis can be monitored by the IR spectral changes in phosphate groups in adenine nucleotides and MIR-IRAS is useful for evaluating time-dependent drug effects of mitochondrial toxicants.

• Korean Journal of Medicinal Crop Science
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• v.18 no.6
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• pp.389-397
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• 2010

This work was to improve antimicrobial activities of horseradish by encapsulated with edible biopolymers such as lecithin and gelatin since it has been difficult to directly use horseradish extracts into foods and food containers due to its strong and undesirable flavors. It was shown that most of the nanoparticles containing the extracts were well formed in round shape with below 400 nm diameter as well as fairly stable and less odd flavors in various pH ranges by measuring zeta potentials. The encapsulation efficiencies of nanoparticles were estimated as 66.6% and 53.4% for lecithin and gelatin, respectively. Minimal Inhibitory Concentration (MIC) of both nanoparticles against G(+), Listeria monocytogenes and G(-), Salmonella typhimurium were also measured as 79 ppm based on AIT concentrations in the extracts, whose activities were about 65% higher than the case of adding crude extract. It was also found that the nanoparticles efficiently penetrated into the cell membrane and started to destruct the cells after 6 hours cultivation under Transmision Electron Microscopy observation. These results prove that the nano-encapsulation of the horseradish extracts can be employed to directly treat into the foods and food containers for antimicrobial purposes with the aids of aerosolization system, by using small amounts of the extracts and having less flavors due to masking effects of nanoparticles.

• Membrane Journal
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• v.17 no.4
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• pp.302-310
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• 2007

The effects of various system parameter on the absorption of sulfur dioxide into the absorbent liquid were investigated in a circulatory porous polymer membrane contactor. A feed gas and an absorbent used in the study were the gas mixture of air and $SO_2$ and the $Na_2SO_3$ aqueous solution, respectively. The separation of sulfur dioxide was measured in terms of the concentration of $Na_2SO_3$ absorbent, the concentration of sulfur dioxide, the feed flow rate, the absorbent velocity and the different membrane material. As the concentration of absorbent increased from 0.05 to 0.2 M, the removal efficiency increased from 74 to 100%. By increasing the concentration of sulfur dioxide from 700 to 2,500 ppm, the removal efficiency decreased from 100 to 75%. Also as the absorbent velocity increased from 2.5 to 15 mL/min, the removal efficiency increased from 85 to 100%. As the porosity of the membrane increased, the removal efficiency increased.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.771-776
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• 2005

In recent days, there is much interest in the biocidal activity of silver since silver is known to be safe and effective as disinfectant and biocidal material against coliforms and viruses. In particular, nano silted silver particles which can be used as effective biocidal material received more attention. Accordingly, it is important to investigate antimicrobial activity and mechanism of nano sized silver particles prepared in a cost-effective manner. In this study, nano sized silver particles were prepared via photoreduction of a silver salt ($AgNO_3$) in the bulk phase of $PEO_{20}-PPO_{70}-PEO_{20}$ (Pluronic 123) block copolymer The antimicrobial efficacy of silver nano particles against E. coli was investigated and compared with that of silver ion as the concentration of silver nano particles, pH ($5.6{\sim}8.2$), temperature ($4^{\circ}C{\sim}35^{\circ}C$) varied in aqueous system. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) was used to examine the nature of damaged microorganism with nano sized silver particles and silver ion. This study showed that antimicrobial efficacy of silver nano particles was approximately one twentieth than that of silver ion. It was more biocidal at higher pH in contrast with silver ion. In addition, nano silver particles was demonstrated to disrupt the outer membrane of E. coli, subsequently causing their aggregation. On the other hand, silver ion diffused into the cell damaging the cytoplasmic membrane without disrupting the outer membrane of E. coli.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.270-275
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• 2006

The cultivated pearls collected for the study were pretreated through the removal of contaminants and the surface bleaching for easy dyeing. Coloring of pearls are necessary after selecting dyes adsorbable to the Conchiolin layer, a kind of hard protein formed in the seawater, covering the surface of the pretreated pearls. Dyes adsorbable to the Conchiolin layers are mostly basic dyes such as Rhodamine 6G(R6G), Rhodamine B(RB), Methylene Blue(MB) etc. and the binary and ternary competitive adsorption were performed by mixing two or three dyes together. The multi-dye adsorption data were compared with the predictions from the ideal adsorbed solution theory(IASI) combined with the single-dye adsorption model, the Langmuir or the Redlich-Peterson(RP) model. The quality of prediction was compared by using determination coefficient($R^2$) and standard deviation(SSE) values. Predictions from the IAST were found to be in good agreement with the data for the R6G/RB binary adsorption to the pearl layers not fractionated with their size, except for the adsorption data for RB at high concentrations. Among the three binary adsorption systems, R6G/RB, R6G/MB, and MB/RB, only the RB sorption data in the R6G/RB binary system was in poor agreement with the IAST prediction. Competitive adsorption data in ternay systems were in good agreement with the predictions from the IAST except for the RB data.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.125-131
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• 2009

Reductive dechlorination of polychlorinated dibenzo-p-dioxins (PCDDs) and its toxicity change were predicted by the linear free energy relationship (LFER) model to assess the zero-valent iron (ZVI) and anaerobic dechlorinating bacteria (ADB) as electron donors in PCDDs dechlorination. Reductive dechlorination of PCDDs involves 256 reactions linking 76 congeners with highly variable toxicities, so is challenging to assess the overall effect of this process on the environmental impact of PCDD contamination. The Gibbs free energies of PCDDs in aqueous solution were updated to density functional theory (DFT) calculation level from thermodynamic results of literatures. All of dechlorination kinetics of PCDDs was evaluated from the linear correlation between the experimental dechlorination kinetics of PCDDs and the calculated thermodynamics of PCDDs. As a result, it was predicted that over 100 years would be taken for the complete dechlorination of octachlorinated dibenzo-p-dioxin (OCDD) to non-chlorinated compound (dibenzo-p-dioxin, DD), and the toxic equivalent quantity (TEQ) of PCDDs could increase to 10 times larger from initial TEQ with the dechlorination process. The results imply that the single reductive dechlorination using ZVI or ADB is not suitable for the treatment strategy of PCDDs contaminated soil, sediment and fly ash. This LFER approach is applicable for the prediction of dechlorination process for organohalogen compounds and for the assessment of electron donating system for treatment strategies.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.10
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• pp.873-882
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• 2009

Sonolysis of TCE (Trichloroethylene) was performed in 584 kHz rectangular reactor. At first, the effect of acoustic power and aqueous temperature which are both important factors to operate ultrasound system on sonolysis of TCE were examined under one side irradiation condition. First degradation rate constants of TCE and chloride yields were increased with increasing acoustic power from 100 to 300 W. And increasing the aqeuous temperature resulted in the increase of first degradation rate constants of TCE and the decrease of chloride yield. Sonolysis of TCE was performed under multi ultrasound irradiation conditions that total acoustic power of 300 W was distributed according to the number of irradiation sides. First degradation rate constants of TCE followed the order 4 sides > 3 sides > 1 side > 2 sides (parallel) > 2 sides (orthogonal). When comparing the experimental results under parallel and orthogonal irradiation conditions of 2 sides with 300 and 450 W, first degradation rate constants of TCE were similar, while production rate constants of hydrogen peroxide were more higher at parallel conditions compared to orthogonal conditions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1239-1244
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• 2003

Microcapsules were prepared by coacervation method using acetone/liquid paraffin system to control the ripening of kimchi. Eudragit E100, which was soluble at below pH 5.0 in aqueous solution, was used to make microcapsules to be sensitive to acidity of kimchi. The microcapsules with Eudragit E100 containing grapefruit seed extract (GFSE) showed the highest yield of 92.13%, the size of microcapsules was decreasing as increasing the amount of aluminium stearate, a dispersing agent. Morphology of the microcapsules determined by scanning electron microscopy showed spherical forms. GFSE, encapsulated antimicrobial agents, was quickly released at acidic buffer (pH 4,5,6) within 1 storage day. However, 70% of encapsulated GFSE in Eudragit E100 microcapsules was continuously released at pH 7 till 3 days, and it was sustained till 9 days. Characteristics of kimchi containing microcapsules of GFSE were analysed with ripening period. Decease of pH in kimchi was retarded with the added GFSE microcapsules till 2 days of fermentation, but GFSE did not affect pH in kimchi after 3 days. Total numbers of microorganisms and lactic acid microorganisms in kimchi were decreased with increasing the amount of the added GFSE microcapsules, however, the effect of controlled released GFSE from pH sensitive Eudragit E100 microcapsules was hard to detect. These results suggest the possibility of pH sensitive microcapsules for high qualify of kimchi.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1703-1710
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• 2009

The single-crystal structure of |$Ca_{35.5}$|[$Si_{121}Al_{71}O_{384}$]-FAU, $Ca_{35.5}Si_{121}Al_{71}O_{384}$ per unit cell, a = 24.9020(10) $\AA$, dehydrated at 673 K and 2 ${\times}\;10^{-6}$Torr, has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd$\overline{3}$m at 294 K. The large single crystals of zeolite Y (Si/Al = 1.70) were synthesized up to diameters of ${\mu}m\;and\;Ca^{2+}$-exchanged zeolite Y were prepared by ion exchange in a batch method of 0.05 M aqueous Ca($NO_3)_2$ for 4 hrs at 294 K. The structure was refined using all intensities to the final error indices (using only the 971 reflections for which $F_o\;>\;4{\sigma}(F_o))\;R_1$ = 0.038 (based on F) and $R_2$ = 0.172 (based on $F^2$). About 35.5 $Ca^{2+}$ ions per unit cell are found at an unusually large number of crystallographically distinct positions, four. Nearly filling site I (at the centers of the double 6-rings), 14.5 octahedrally coordinated $Ca^{2+}$ ions (Ca-O = 2.4194(24) $\AA$ and O-Ca-O = 87.00(8) and 93.00($8^o$) are found per unit cell. One $Ca^{2+}$ ion per unit cell is located at site II’ in the sodalite cavity and extends 0.50 $\AA$ into the sodalite cavity from its 3-oxygen plane (Ca-O = 2.324(13) $\AA$ and O-Ca-O = 115.5(10)o). The remaining twenty $Ca^{2+}$ ions are found at two nonequivalent sites II (in the supercages) with occupancies of 10 and 10 ions, respectively. Each of these $Ca^{2+}$ ions coordinates to three framework oxygens, either at 2.283(3) or 2.333(5) $\AA$, respectively, and extends either 0.24 or 0.54 $\AA$, respectively, into the supercage from the three oxygens to which it is bound. In this crystal, site I is the most populated; sites II’ and II are only sparsely occupied.$Ca^{2+}$+ appears to fit the octahedral site I best. No cations are found at sites III or III’, which are clearly less favorable for $Ca^{2+}$ ions in dehydrated zeolite Y.