• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.345-351
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• 1998

In an effort to develop a potent system for the production of various dp (degree of polymerization) chitooligosaccharides, 32 enzymes or microbial systems were screened for chitosanolytic acitivity using chitosan as a substrate. The efficiency of each enzyme system was evaluated by the changes of turbidity and viscosity of chitosan solution, the amount of precipitate and the reducing sugar-producing activity in the enzymatic reaction mixture. Based on these assay methods for the chitosanase activity, Bacillus sp. P2l out of 32 screened systems showed highly potent endochitosanase, which was comparable with a commercially available enzyme (E7). Chitooligosaccharides of dp 3-7 were separated by TLC as major enzymatic reaction products, suggesting that the chitosanase from Bacillus sp. P2l be endo-splitting type.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.393-400
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• 2005

A novel evaluation method was investigated for measuring the ability of acid amplification of acid amplifier. The method was based on the measurement of conductivity change by the acid generation according to UV radiation. It was found that the decrease of conductivity was caused by photopolymerization of epoxy monomer during UV curing process of ink film and by the rate of UV curing. In this paper, the novel acid amplifiers were synthesized and measured thermal stability by means of DSC. It was found that mono-type acid amplifiers were more stable than di-type. It was possible to make the dynamical evaluation of the curing rate of UV curable ink in curing process by this method.

• Development and Reproduction
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• v.11 no.2
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• pp.85-96
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• 2007

Mesenchymal stem cells (MSC) are promising candidates for cell-based therapies. One major obstacle for their clinical use is the unsafety of fetal bovine serum (FBS), which is a crucial part of all media currently used for the culture of MSC. We investigated the effect of human cord serum (HCS) on the growth response, mRNA and protein expressions of human amnion-derived stem cells (HAM). HAM were isolated from the amnion after a Caesarean section and cultured in DMEM supplemented with 10% FBS, 5% HCS or 10% HCS. During culture, their biological characteristics at earlier and later passages were analyzed using RT-PCR and immunocytochemistry. Regardless of serum sources, HAM showed the prominent expression of Oct-4, Rex-1, SCF, FGF-5, BMP-4, nestin, GATA-4, NCAM and HLA ABC genes. The expression profile was observed even at later passages. Similarly, HAM cultured in either FBS or HCS exhibited the distinct protein expression of collagen I, II, III and XII, fibronectin, $\alpha$-smooth muscle actin, vimentin, CK18, CD54, FSP, TRA-1-60, SSEA-3, -4 and HLA ABC. However, desmin expression was only observed in HAM cultured in medium supplemented with FBS and vWF expression was only found in HAM cultured in medium supplemented with HCS. Overall pattern of gene and protein expression of HAM was typical of known adult stem cells such as bone marrow-derived MSC. In conclusion, HCS could be as effective as FBS for the culture of HAM.

• Polymer(Korea)
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• v.29 no.5
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• pp.433-439
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• 2005

The copolymers were prepared by the emulsion copolymerization of fluoroalky lacrylate-stearylacrylate-m-isopropenyl-${\alpha},\;{\alpha}'$-dimethylbenzyl isocyanate (TMI) in order to obtain water repellent polymers. The respective copolymerization rates of the three monomers considerably depended upon the use of the nonionic emulsifier and the nonionic-cationic mixed emusifier, and the optimum conditions were obtained. The particle sizes of the copolymers were in the range of 105 to 222nm. The particle sizes of the copolymers prepared by the use of the mixed emulsifiers were smaller than those of the copolymers prepared by the use of the nonionic emulsifier. The reactions of both TMI-N-methyl acetamide and TMI-cellobiose did not take place. However, the reaction of TMI-n-butylamine occurred. The water contact angles before and after washing three times for nylon and poly(ethylene terephthalate) (PET) fabrics coated with the copolymer prepared by the use of mixed emulsifier were about $139^{\circ}\;and\;133^{\circ}$ Therefore, the copolymer showed good durable repellency for nylon and PET.

• Korean Journal of Plant Taxonomy
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• v.35 no.3
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• pp.161-174
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• 2005

In order to presume the relationships between two species of P. ternata and P. tripartia, and their populations of the Korean Pinellia, RAPD analysis was performed. The length of the amplified DNA fragments ranged from 300 to 2,500bp. Seventy scorable RAPD makers were found from the PCR reactions with 7 random oligoprimers and were analyzed by Nei-Li's genetic coefficient. Also, some regional groups instead of same taxa were clustered from the phenogram of UPGMA analysis and NJ tree. Populations within each species were clustered at low genetic distance, there had the closed relationship. According to the regional individuals, Pinellia ternata was showed the variation pattern of morphological (leaf shape and flower color) and cytological characters(somatic chromosome numbers). So we suggested to difference of characteristic variety based on variety of habitat. According to this study, new species (Pinellia sp.) was affiliated with Pinellia and had the closest relationship with Hallasan and Japan population. The RAPD data was very useful to define the genetic variation and to discuss the relationships among the intraspecific taxa and their populations of the Korean Pinellia.

• Polymer(Korea)
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• v.39 no.1
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• pp.56-63
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• 2015

The object of this study is to prepare microcapsules containing a diisocyanate compound, apply them to self-healing protective coating, and evaluate the self-healing capability of the coating by atmospheric moisture. Isophorone diisocyanate (IPDI) polymerized under humid atmosphere, indicating that IPDI can be used as a healing agent. Microencapsulations of IPDI were conducted via interfacial polymerization of a polyurethane prepolymer with diol compounds. The formation of microcapsules was confirmed by Fourier-transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The mean diameter, size distribution, morphology and shell wall thickness of microcapsules were investigated by optical microscopy and scanning electron microscopy (SEM). The properties of microcapsules were studied by varying agitation rates and diol structure. The self-healing coatings were prepared on test pieces of CRC board. When scratch was generated in the coatings, the core material flew out of the microcapsules and filled the scratch. The self-healing coatings were damaged and healed under atmosphere with 68~89% relative humidity for 48 h, and SEM and impermeability test for the specimens showed that the scratch could be healed by atmospheric moisture.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.539-544
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• 2020

A three-dimensional (3D) porous polyaniline (PANI) film was fabricated by a combined photo-and soft-lithography technique based on a large-area nanopillar array, followed by a controlled chemical dilute polymerization. The as-obtained 3D PANI film consisted of hierarchically interconnected PANI nanofibers, resulting in a 3D hierarchical nanoweb film with a large surface and open porous structure. Using electrochemical measurements, the resulting 3D PANI film was demonstrated as a flexible pH sensor electrode, exhibiting a high sensitivity of 60.3 mV/pH, which is close to the ideal Nernstian behavior. In addition, the 3D PANI electrode showed a fast response time of 10 s, good repeatability, and good selectivity. When the 3D PANI electrode was measured under a mechanically bent state, the electrode exhibited a high sensitivity of 60.4 mV/pH, demonstrating flexible pH sensor performance.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.3
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• pp.234-240
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• 2007

Purpose: In this study we propose a block-iterative method for reconstructing Compton scattered data. This study shows that the well-known expectation maximization (EM) approach along with its accelerated version based on the ordered subsets principle can be applied to the problem of image reconstruction for Compton camera. This study also compares several methods of constructing subsets for optimal performance of our algorithms. Materials and Methods: Three reconstruction algorithms were implemented; simple backprojection (SBP), EM, and ordered subset EM (OSEM). For OSEM, the projection data were grouped into subsets in a predefined order. Three different schemes for choosing nonoverlapping subsets were considered; scatter angle-based subsets, detector position-based subsets, and both scatter angle- and detector position-based subsets. EM and OSEM with 16 subsets were performed with 64 and 4 iterations, respectively. The performance of each algorithm was evaluated in terms of computation time and normalized mean-squared error. Results: Both EM and OSEM clearly outperformed SBP in all aspects of accuracy. The OSEM with 16 subsets and 4 iterations, which is equivalent to the standard EM with 64 iterations, was approximately 14 times faster in computation time than the standard EM. In OSEM, all of the three schemes for choosing subsets yielded similar results in computation time as well as normalized mean-squared error. Conclusion: Our results show that the OSEM algorithm, which have proven useful in emission tomography, can also be applied to the problem of image reconstruction for Compton camera. With properly chosen subset construction methods and moderate numbers of subsets, our OSEM algorithm significantly improves the computational efficiency while keeping the original quality of the standard EM reconstruction. The OSEM algorithm with scatter angle- and detector position-based subsets is most available.

• Development and Reproduction
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• v.11 no.3
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• pp.167-177
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• 2007

In the present study, we isolated three human adult stem cells including adipose tissue-derived stem cells(HAD), umbilical cord-derived stem cells(HUC), and amnion-derived stem cells(HAM) and analysed their characteristics. And we examined whether HAD could be used as therapeutical cells for the heart diseases. Both HAM and HUC appeared very similar morphology but HAD was different. Doubling time of HUC was most fast, but total doubling numbers of HUC was same with HAM. Total doubling numbers of HAD was much more than others. Expression patterns of genes and proteins of three human adult stem cells were very similar. Also they were differentiated into adipocytes, osteocytes, and chondrocytes. In addition, they expressed many cardiomyocyte-related genes. But expression pattern of genes is a little different. When HAD were cultivated in the presence or absence of various combinations of BMP and FGF after 5-azacytidine expose for 24 h, expression of Cmlc-1, and ${\alpha}1c$ genes was significantly increased. However, expression of troponin T, troponin I and Kv4.3 genes was not changed. Based on these observations, it is suggested that HAD, HUC, and HAM might be used as potentially therapeutical cells for clinical application.