• Membrane Journal
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• v.27 no.6
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• pp.528-535
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• 2017

In this study, halogen element was introduced into polyphenylene oxide polymer using bromination reaction, and then halogen element was replaced with imidazolium. Imidazolium corporated polyphenylene oxide polymer was synthesized and the synthesis was confirmed by various instrumental characterization. In addition, gas permeation properties of $O_2$, $N_2$, $CO_2$ were studied with different imidazolium contents. As the content of imidazolium increased, the ion exchange capacity increased and the mechanical strength decreased. The gas permeance showed a tendency to decrease slightly with increaing imidazolium contents. Whereas, it was confirmed that the tendency of $CO_2/N_2$ ideal selectivity increased as the imidazolium contents increased.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.5
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• pp.437-447
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• 2012

Ceria ($CeO_2$) was used to scavenge free radicals which attack the membrane in the polymer electrolyte membrane water electrolysis (PEMWE) circumstance and to increase the duration of the membrane. In order to improve the electrochemical, mechanical and electrocatalytic characteristics, engineering plastic of the sulfonated polyether ether ketone (SPEEK) as polymer matrix was prepared in the sulfonation reaction of polyether ether ketone (PEEK) and the organic-inorganic blended composite membranes were prepared by sol-gel casting method with loading the highly dispersed ceria and cesium-substituted tungstophosphoric acid (Cs-TPA) with cross-linking agent contents of 0.01 mL. In conclusion, CL-SPEEK/Cs-TPA/ceria (1%) membrane showed the optimum results such as 0.130 S/cm of proton conductivity at $80^{\circ}C$, 2.324 meq./g-dry-membrane of ion exchange capacity and mechanical characteristics, and 65.03 MPa of tensile strength which were better than Nafion 117 membrane.

• Macromolecular Research
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• v.16 no.6
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• pp.549-554
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• 2008

Proton conducting crosslinked membranes were prepared using polymer blends of polystyrene-b-poly(hydroxyethyl acrylate)-b-poly(styrene sulfonic acid) (PS-b-PHEA-b-PSSA) and poly(vinyl alcohol) (PVA). PS-b-PHEA-b-PSSA triblock copolymer at 28:21:51 wt% was synthesized sequentially using atom transfer radical polymerization (ATRP). FT-IR spectroscopy showed that after thermal ($120^{\circ}C$, 2 h) and chemical (sulfosuccinic acid, SA) treatments of the membranes, the middle PHEA block of the triblock copolymer was crosslinked with PVA through an esterification reaction between the -OH group of the membrane and the -COOH group of SA. The ion exchange capacity (IEC) decreased from 1.56 to 0.61 meq/g with increasing amount of PVA. Therefore, the proton conductivity at room temperature decreased from 0.044 to 0.018 S/cm. However, the introduction of PVA resulted in a decrease in water uptake from 87.0 to 44.3%, providing good mechanical properties applicable to the membrane electrode assembly (MEA) of fuel cells. Transmission electron microscopy (TEM) showed that the membrane was microphase-separated with a nanometer range with good connectivity of the $SO_3H$ ionic aggregates. The power density of a single $H_2/O_2$ fuel cell system using the membrane with 50 wt% PVA was $230\;mW/cm^2$ at $70^{\circ}C$ with a relative humidity of 100%. Thermogravimetric analysis (TGA) also showed a decrease in the thermal stability of the membranes with increasing PVA concentration.

• Preventive Nutrition and Food Science
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• v.1 no.1
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• pp.111-116
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• 1996

Polyphenol oxidase(PPO) isolated from the crude extract of ascidian, Halocynthia roretzi, showed higher affinity for catechol than tyrosine or DL-DOPA. Successful enzyme assay could be performed at $25^{\circ}C$, 10min. by mixing 0.2ml of crude enzyme extract with 2.8ml of 0.13M catechol in 0.1M sodium phosphate buffer(pH 6.4). The specific activity of PPO which had been purified with a combination of ammonium sulfate treatment, ion exchange chromatography on DEAE-cellulose, and gel filtration on Sepharose 6B was 13-fold disc gel electrophoresis. The activity of PPO was stable from pH 5.0 to 8.0 and showed the peak activity at pH 6.4 .The optimum reaction temperature for PPO oxidation on catechol was 35$^{\circ}C$ and those enzyme were heat stable up to 4$0^{\circ}C$. Molecular weigth of the enzyme was estimated about 170kDa. One molecule was found to be composed of gour subunits. Two of them had molecular weigh of 55kDa and the others 30kDa. The {TEX}$K_{m}${/TEX} values, {TEX}$V_{max}${/TEX} and catalytic efficiency({TEX}$V_{max}${/TEX}/{TEX}$K_{m}${/TEX}) for catechol were 0.12mM, 2.5mM/liter/min. and {TEX}$0.18min^{-1}${/TEX} respectively. The substrate affinity and electrophorectic pattern suggested that the enzyme of ascidian was considered to be not tyosine but catechol oxidase.

• Membrane and Water Treatment
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• v.9 no.2
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• pp.95-104
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• 2018

Copper pollution around the world has caused serious public health problems recently. The heavy metal adsorption on traditional membranes from wastewater is limited by material properties. Different adsorptive materials are embedded in the membrane matrix and act as the adsorbent for the heavy metal. The carbonized leaf powder has been proven as an effective adsorbent material in removing aqueous Cu(II) because of its relative high specific surface area and inherent beneficial groups such as amine, carboxyl and phosphate after carbonization process. Factors affecting the adsorption of Cu(II) include: adsorbent dosage, initial Cu(II) concentration, solution pH, temperature and duration. The kinetics data fit well with the pseudo-first order kinetics and the pseudo-second order kinetics model. The thermodynamic behavior reveals the endothermic and spontaneous nature of the adsorption. The adsorption isotherm curve fits Sips model well, and the adsorption capacity was determined at 61.77 mg/g. Based on D-R model, the adsorption was predominated by the form of physical adsorption under lower temperatures, while the increased temperature motivated the form of chemical adsorption such as ion-exchange reaction. According to the analysis towards the mechanism, the chemical adsorption process occurs mainly among amine, carbonate, phosphate and copper ions or other surface adsorption. This hypothesis is confirmed by FT-IR test and XRD spectra as well as the predicted parameters calculated based on D-R model.

• Journal of the Korean Electrochemical Society
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• v.22 no.3
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• pp.122-127
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• 2019

In this study, we investigate the electrochemical performance of lithium terephthalate (LTA) battery using graphite coated metal current collector to overcome the disadvantages of organic batteries which is high interfacial resistance between current collector and electrode. The LTA anode material is synthesized by acid-based ion exchange reaction without impurities. The contact properties between stick-type LTA-based electrode and graphite coated current collector are estimated by the cross-section SEM and EIS. The graphite coated current collector significantly reduced the interfacial resistance of the LTA battery. The second discharge capacities of bare current collector LTA and graphite coated current collector LTA batteries are 107.6 mAh/g and 148.8 mAh/g at 0.1C, respectively. The graphite coated current collector LTA batteries show higher cycle life, higher discharge capacity, and higher rate-capability than bare LTA batteries.

• Journal of Life Science
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• v.11 no.2
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• pp.111-115
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• 2001

This study was designed to clone the SNF2/SW12 helicase-related genes from the fission yeast Schizosaccha-romyces pombe and thereafter to elucidate the common functions of the proteins in this family. The $hrp^{2+}$gene was cloned by polymerase chain reaction amplification using degenerative primers from conserved SNF2 motifs within the ERCC6 gene, which encodes a protein involved in DNA excision repair. Like other SNF2/SW12 family proteins, the deduced amino acid sequence of Hrp2 contains DNA-dependent ATPase/7 helicase domains as well as the chromodomain and the DNA binding domain. This configuration is similar to that of mCHD1 (mouse chromo-ATPase/helicase-DNA-dinding protein 1), suggesting that Hrp2 is a S. pombe homolog of mCHD1, which is thought to function in altering the chromatin structure to control the gene expression. To characterize the function of Hrp2, 4 Uracil-Hrp2 fusion protein, it was purified near homogeneity by affinity chromatography on $Ni^{2+}$-NTA agarose, DEAE-Sepharose ion exchange arid Sephacryl S-200 gel filtration chromatographies. The purified fusion protein exhibited DNA-dependent ATPase activity, which was stimulated by both double-stranded and single-stranded DNA. To determine the steady-state level of $hrp^{2+}$ transcripts during growth, cells were cultured in medium and collected at every 2hr to prepare total RNAs. The northern blot analysis showed that the level of $hrp^{2+}$ transcripts reached its maximum before the cells entered the exponential growth phase and then decreased gradually, This result implies that Hrp2 may be required at early stages of cell growth.h.

• Tuberculosis and Respiratory Diseases
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• v.43 no.1
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• pp.30-37
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• 1996

Background: The extraction methods of DNA from clinical samples are the major obstacle to use the PCR(polymerase Chain Reaction) in routine labortary for early detection of M. tuberculosis. We tried to improve the extraction method of DNA from sputum for establishment of the PCR in routine labortary by reducing the possibility of cross contamination and performing it easily and safely. Methods: We used the $InstaGene^{TM}$ DNA extraction kit(BioRad Co.) using Chelex 100 ion exchange resin for preparation of DNA. We compared InstaGene method in 100 cases of sputum from proteinase K method which is known as the most commonly used method for DNA purification(Experiment 1). And we compared InstaGene method in 98 cases of sputum from Microwave method developed by a company in Korea(Experiment 2). In experiment 1,245bps of IS6110 were amplified and then 188bps were amplified by nested PCR. In experiment 2,536bps in primary PCR and 276bps in nested PCR were amplified and analysed by agarose gel electrophoresis and EtBr staining. Results: When we chose AFB smear, culture, or AFB smear and culture as a standard test, PCR had low specificity and positive predictive value in both experiments. The InstaGene method has higher value in sensitivity and negative predictive value significantly than proteinase K method. The InstaGene method and the Microwave methods were similar in sensitivity, specificity, positive predictive value and negative predictive value. Conclusion: Even though both methods had lower possibility of cross contamination, shorter time requirement, simplicity, and economic advantages than Proteinase K method, the InstaGene method was a little simpler than the Microwave method. Therefore, in terms of usefulness in clinical application, the Instagene method seems to be the most useful method in DNA extraction for detection of M. tuberculosis using PCR. The reliability of this method will be clarified by further studies with enough clinical samples.

• Economic and Environmental Geology
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• v.38 no.3 s.172
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• pp.207-219
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• 2005

The physical and chemical characteristics of soils in a small watershed were investigated and the effect of geology and land use on soil quality were examined by using multivariate statistical methods, principal components analysis and discriminant analysis. The soil developed from andesite had finer texture and higher contents of water extractable inorganic components, clay, and mafic minerals than the soil developed from granite. It is considered that the accumulation of salts in the farmland soils indicated by electrical conductivity, contents of cations and anions and pH was caused by fertilizer input during cultivation. The low contents of organic matter in the farmland soils was due to the enhanced oxidation of organic matter by tillage and by the harvest of crops. The contents of inorganic components are increased as following order: upland > orchard > paddy field > forest. The high contents of water soluble $SO_4\;^{2-}$ of paddy soils is due to the oxidation of sulfides mineral formed during the flooding period during the air-dry and extraction. The results of principal components analysis show the difference of soil quality was controlled by geology and land use. PCI indicate the input of fertilizer, mineral weathering and ion exchange reaction by application of nitrogenous fertilizers. The results of two discriminant analyses using water extractable inorganic components and their ratios by land use were also clearly classified by discriminant function 1 and 2. In discriminant analysis by components, discriminant function 1 indicated the effect of fertilizer application and increased as following order: upland > orchard > paddy field > forest soil. The investigated and predicted data for land use from discriminant analysis showed similar results. The discriminant analysis can be used as a useful method certifying the change of land use.

• Journal of Dairy Science and Biotechnology
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• v.15 no.1
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• pp.1-9
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• 1997

This study was conducted to efficiently separate the Ig from Korean native cattle colostrum and to utilize them as an immunogen for the production of antibodies aginst rabbit. The results obtained were as follows : 1. About 84% of Ig G could be separated from Korean native cattle colostrum by·gel filtration using Superose 12 column on HPLC. The separation profile of Korean native cattle colostral immunoglobulin was similar that of Holstein colostral Ig. 2. Separation of Korean native cattle colostral Ig by anion exchange chromatography using Mono Q column on HPLC was poor resolution chromatographic pattern. 3. Hi-Trap Protein G column showed better results than the Protein A Sepharose CL-4B column in the Ig G binding capacity from Korean native cattle colostral Ig. 4. Protein G Sepharose Fast Flow system resulted in higher Ig g binding capacity as the industrial size scale-up approach. 5. Sufficient titer reaction of antibody to Korean native cattle colostral Ig G was confirmed by ELISA.