• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.114-119
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• 2016

In this study, we tried to add the conductivity to natural polymer like bacterial cellulose (BC) coated with the conductive polymer PEDOT:PEG, graphene and silver nano-wire (AgNW). Sulfuric acid of 10 to 20% was previously mixed with PEDOT:PEG and then the solution was electron spin-coated on the BC membrane. And then, additive coating with graphene and AgNW were done to improve conductivity, which was examined by hall effect. As the result, we confirmed a considerable improvement of conductivity compared to BC-coated film without sulfuric acid treatment as $2.487{\times}10^{10}$ vs $8.093{\times}10^{15}$ ($1/cm^3$), showing higher electron density with $3.25{\times}10^5$ times. Also, we identified that changed particle type to the polymer type by sulfuric acid using SEM analysis. For FT-IR analysis, it was confirmed that S-O radical ($1200cm^{-1}$) increased in the sulfuric acid treatment than non-treated sulfuric acid. As the method used very small amount of PEDOT:PEG, its transparency could be kept, and pre-treatment process of sulfuric acid will be able to simplify the production process.

• Analytical Science and Technology
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• v.27 no.1
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• pp.66-77
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• 2014

This study was carried out to examine the authenticity discrimination of circulated vegetable oils by using carbon isotope ratio (${\delta}^{13}C$) and fatty acid composition. This analysis was applied to vegetable oils which we can buy in Korean markets, and the analytical instrument was measured by using EA-IR/MS for ${\delta}^{13}C$ and GC/FID for fatty acid composition. ${\delta}^{13}C$ was separated into 3 groups as $C_3$ plant including sesame oil, $C_4$ plant including maize oil, and rice bran oil. Fatty acid composition was significantly different among vegetable oils. In addition, the interval of low and high price vegetable oils was classified through the scatter plot analysis showing the correlation of the ${\delta}^{13}C$ and fatty acid composition. Therefore, through a simultaneous determination of the ${\delta}^{13}C$ and fatty acid composition, we are able to determine the majority of vegetable oils. It help to ensure food safety in Korean market by exclusion of economically modified adulteration in food.

• Membrane Journal
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• v.28 no.2
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• pp.121-128
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• 2018

Terpolymers, which are chemical compounds composed of three different chemical compounds, have rarely been utilized for gas separation membranes. In this study, we demonstrate a simple process to fabricate a composite membrane for $CO_2/N_2$ separation based on a terpolymer synthesized from poly(2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] ethylmethacrylate)(PBEM), poly(oxyethylene methacrylate)(POEM), and methyl methacrylate (MMA) via free radical polymerization. A solution of the as-synthesized PBEM-PMMA-POEM was coated onto a microporous polysulfone (PSf) support to form a composite membrane. The successful polymerization and the characteristics and morphology of the membrane were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FE-SEM). The gas permeance and $CO_2/N_2$ selectivity of the PBEM-PMMA-POEM terpolymer membrane were measured at $25^{\circ}C$. A maximum $CO_2/N_2$ selectivity of 30.2 was obtained at a $CO_2$ permeance of 57.4 GPU ($1GPU=10^{-6}cm^3$(STP)/($s\;cm^2\;cmHg$)).

• Korean journal of food and cookery science
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• v.25 no.2
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• pp.252-259
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• 2009

Ergosterol is the significant component of the cell wall of fungi. Its presence is regarded as evidence of fungi contamination in grain and other foods. Many studies on ergosterol detection have been carried out using chemical methods, but those methods required complicated pre-treatments and long analysis times. In this study, an amperometric biosensor was developed for fast and precise ergosterol detection. The biosensor system used the electron transfer of hydrogen peroxide produced from the reaction of ergosterol with cholesterol oxidase. The biosensor system consisted of a peristaltic pump, a syringe loading sample injector, an enzyme reactor, a fabricated flow-through cell containing a working electrode, a reference electrode and a counter electrode, and a potentiostat/recorder. The working electrode was prepared by coating modified multi-wall carbon nanotube (MWNT) on glassy carbon electrode. The $MWNT-NH_2$ coated glassy carbon electrode linearly responded to hydrogen peroxide in the range of $1{\times}10^{-5}{\sim}8{\times}10^{-5}$ M with a detection limit of $10^{-7}$ M in the basic performance test. The currents produced from the ergosterol biosensor showed the linearity in a range from $1.0{\times}10^{-6}$ M to $1.0{\times}10^{-5}$ M ergosterol.

• Membrane Journal
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• v.26 no.6
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• pp.480-489
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• 2016

In this study, the PVdF/MGO composite nanofiber membranes (PMGs) introducing Iron oxide-Graphene oxide ($Fe_3O_4/GO$, Metallic graphene oxide; MGO) was prepared via electrospinng method and its arsenic removal characteristics were investigated. The thermal treatment was carried out to improve the mechanical strength of nanofiber membranes and then the results showed that of outstanding improvement effect. However, in case of PMGs, the decreasing tendency of mechanical strength was indicated as increasing MGO contents. From the results of pore-size analysis, it was confirmed that the porous structured membranes with 0.3 to $0.45{\mu}m$ were prepared. For the water treatment application, the water flux measurement was carried out. In particular, PMG2.0 sample showed about 70% improved water flux results ($153kg/m^2h$) compared to that of pure PVdF nanofiber membrane ($91kg/m^2h$) under the 0.3 bar condition. In addition, the PMGs have indicated the high removal rates of both As(III) and As(V) (up to 81% and 68%, respectively). Based on the adsorption isotherm analysis, the adsorption of As(III) and As(V) ions were both more suitable for the Freundlich. From all of results, it was concluded that PVdF/MGO composite nanofiber membranes could be utilized as a water treatment membrane and for the Arsenic removal applications.

• Journal of Technology Innovation
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• v.24 no.4
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• pp.27-53
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• 2016

This case analyzed the efficiency of 79 R&D projects performed within one private research center in machine tools industry. DEA was used for efficiency analysis. Input variables were R&D investment expense and man-month. Output variables were achievement rate on target development period and expected net sales within 5-years. Samples are divided into product development, Prior technology development, and control technology development. The key result is that Prior technology showed the lowest efficiency because of high uncertainty. It was so difficult to determine its goals and to make its specific plans. With respect to scale, the proportions of CRS(constant returns to scale) were 34.6%, 14.3% and 38.9% for product development, prior technology, control technology respectively. As for IRS(increase returns to scale), they were 53.8%, 85.7% and 38.9% for product development, prior technology, control technology respectively. As for DRS(decrease returns to scale) they were 11.5%, 0% and 22.2% for product development, prior technology, control technology respectively. On the whole, in this case, insufficient input was more problematic than excessive input, which means the lack of investment in R&D. Prior technology can be the source of the future competitiveness of companies. To operate inefficient DMU efficiently, the optimal input should be managed and it is derived from comparison with the reference group.

• Journal of Pharmaceutical Investigation
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• v.25 no.1
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• pp.9-17
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• 1995

To stabilize omeprazole(OMP), ethylenediamine(ED) complex of omeprazole(OMPED) was prepared by reaction between OMP and ED in methanol, and the complex formation was confirmed by the instrumental analysis, i.e., IR, DSC, EA, NMR, MS and XRD. The rates of decomposition of OMP and OMPED in aqueous solution and the shelf lives at standard temperature were measured by accelerated stability analysis. The results are summarized as follows; The mole ratio of OMP and ED in OMPED complex is 1:1, the energy of formation within OMPED might be combined between polar imidazole group of OMP with induced a dipole amine group in the readily polarizable ED molecule. At standard temperature the degradation rate constant of OMP in aqueous solution is $2.540{\times}10^{-2}\;hr^{-1}$ and the shelf life is 4.15 hrs, and in the case of OMPED the degradation rate constant is $7.986{\times}10^{-4}\;hr^{-1}$ and the shelf life is 131.96 hrs. So, the OMPED has about 31 times longer shelf life than OMP. The activation energy of OMP and OMPED are 5.23 and 18.55 kcal $mole^{-1}$ respectively. The stability of OMP is dependent chiefly on pH in the solutions and it decomposes readily in acidic medium by hydrogen ion catalized reaction but becomes stable beyond pH 9.0. In case of the ED-complex, OMPED is stable in neutral as well as in dilute acidic solutions even in pH 6, OMPED is very stable to light(UV), that is, the rate constant and shelf life of OMP are $k=1.0188{\times}10^{-2}\;day^{-1}$, $T_{90%}=4.5 \;days$, on the other hand, the those of OMPED are $k=7.138{\times}10^{-4}\;day^{-1}$, $T_{90%}=64.1\;days$, respectively. From the above results, it is thought that new dosage forms could be developed by using the OMPED as a potential OMP complex.

• Microbiology and Biotechnology Letters
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• v.46 no.2
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• pp.120-126
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• 2018

As a basic study for environment-friendly production of bacterial cellulose (BC) dressing with antimicrobial activity, we isolated and identified acetic acid bacteria which are resistant to silver ions and can biosynthesize silver nanoparticles. Furthermore, conditions of BC production by selected strain were also investigated. Strain G7 isolated from decayed grape skin was able to grow in the presence of 0.1 mM $AgNO_3$ which was identified as Acetobacter intermedius based on 16S rRNA gene analysis. BC production was the highest in a medium containing 2% glucose as a carbon source, 2% yeast extract as a nitrogen source, and 0.115% acetic acid as a cosubstrate. Structural properties of BC produced in optimal medium were studied using Fourier-transform infrared spectroscopy and X-ray diffractometer, and it was found that BC produced was cellulose type I that was the same as a typical native cellulose. When strain G7 was cultured in an optimal medium containing 0.1 mM $AgNO_3$, the color of the culture broth turned into reddish brown, indicating that silver nanoparticles were formed. As a result of UV-Vis spectral analysis of the culture, it was found that a unique absorption spectrum of silver nanoparticles at 425 nm was also observed. Scanning electron microscopic observations showed that silver nanoparticles were formed on the surface and pores of BC membrane.

• Nutrition Research and Practice
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• v.9 no.4
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• pp.379-384
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• 2015

BACKGROUND/OBJECTIVE: Apolipoprotein A5 gene promoter region T-1131C polymorphism (APOA5 T-1131C) is known to be associated with elevated plasma TG levels, although little is known of the influence of the interaction between APOA5 T-1131C and lifestyle modification on TG levels. To investigate this matter, we studied APOA5 T-1131C and plasma TG levels of subjects participating in a three-month lifestyle modification program. SUBJECTS/METHODS: A three-month lifestyle modification program was conducted with 297 participants (Age: $57{\pm}8years$) in Izumo City, Japan, from 2001-2007. Changes in energy balance (the difference between energy intake and energy expenditure) and BMI were used to evaluate the participants' responses to the lifestyle modification. RESULTS: Even after adjusting for confounding factors, plasma TG levels were significantly different at baseline among three genotype subgroups: TT, $126{\pm}68mg/dl$; TC, $134{\pm}74mg/dl$; and CC, $172{\pm}101mg/dl$. Lifestyle modification resulted in significant reductions in plasma TG levels in the TT, TC, and CC genotype subgroups: $-21.9{\pm}61.0mg/dl$, $-20.9{\pm}51.0mg/dl$, and $-42.6{\pm}78.5mg/dl$, respectively, with no significant differences between them. In a stepwise regression analysis, age, APOA5 T-1131C, body mass index (BMI), homeostasis model assessment-insulin resistance (HOMA-IR), and the 18:1/18:0 ratio showed independent association with plasma TG levels at baseline. In a general linear model analysis, APOA5 T-1131C C-allele carriers showed significantly greater TG reduction with decreased energy balance than wild type carriers after adjustment for age, gender, and baseline plasma TG levels. CONCLUSIONS: The genetic effects of APOA5 T-1131C independently affected plasma TG levels. However, lifestyle modification was effective in significantly reducing plasma TG levels despite the APOA5 T-1131C genotype background.

• Journal of the Mineralogical Society of Korea
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• v.20 no.3
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• pp.223-229
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• 2007

The mechanism of hydrothermally synthesizing Na-A zeolite from siliceous mudstone at a $Na_2O/SiO_2$ ratio of 0.6, a $SiO_2/Al_2O_3$ 2.0 and a $H_2O/Na_2O$ 119 has been observed by IR, DTA, XRD and SEM. This mudstone is a tertiary periodic sedimentary rock and widely spreads around the Pohang area. In the early hydrothermal synthesis at $80^{\circ}C$ in an autoclave, sodium silicate and sodium aluminate were found to be preferentially reacted to generate Na-A type zeolite. Gibbsite and bayerite were also formed due to the presence of extra aluminum oxide in the feedstock. As reaction time in-creased up to 50 h, residual sodium aluminatewas reacted with siliceous mudstone, causing the Na-A zeolite crystal to grow and the hydroxylsodalite to generate. Therefore, in the $14{\sim}50\;h$ synthetic time, Na-A zeolite and hydroxylsodalite were formed. Also, if reaction time passed over 50 h, a part of the Na-A zeolite was finally redissolved and reacted with hydroxylsodalite to synthesize Na-P zeolite, generating porous surface of Na-A zeolite and disappearing hydroxylsodalite.