• Journal of Pharmaceutical Investigation
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• 제41권3호
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• pp.173-178
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• 2011

Injectable chitosan hydrogels have attracted great potential due to sustained-release property and safety. Here, palmityl-acylated glycol chitosan (Pal-GC) was used to generate physically cross-linked hydrogels by virtue of hydrophobic attraction of linear fatty carbons. Glycol chitosan was chemically modified with N-hydroxysuccinimide-activated palmitic acid in dimethylsulfoxide (DMSO) containing dimethylaminopyridine. Through a series of preparation steps of (i) dialysis with DMSO, (ii) addition of palmityl-acylated exendin-4 (Ex4-C16), and (iii) dialysis with water, Pal-GC was self-assembled to form physically cross-linked hydrogels entrapped with Ex4-C16. The Pal-GC derivative was analyzed by using 1H NMR, and the surface morphology of Pal-GC hydrogels formed was examined by scanning electron microscopy. Also, the hypoglycemic effect induced by Pal-GC hydrogels containing Ex4-C16 (250 nmol/kg) was evaluated in non-fasted type 2 diabetic db/db mice and compared with GC hydrogels containing native Ex4 at the same dose. Results showed that palmityl group was successfully conjugated with the amines of glycol chitosan, and that Pal-GC efficiently generated the hydrogels formation. Moreover, Pal-GC hydrogels containing Ex4-C16 was found to greatly prolong the hypoglycemia duration (~ 4 days). This was due to the dual-functions of the palmityl groups present in both GC and exendin-4 such as hydrophobic attraction and plasma albumin-binding. We consider this new type of self-assembled GC hydrogels loaded with Ex4-C16 would be a promising long-acting sustained-release system with anti-diabetic property.

• 대한의용생체공학회:의공학회지
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• 제40권5호
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• pp.143-150
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• 2019

To evaluate the toxicity of ophthalmic drug, the Draize test and Bovine Corneal Opacity and Permeability (BCOP) test commonly used. In Draize test, experimental animals were under stress and pain due to long-term exposure of drug. In addition, regarding physiological functions, animal model is not perfectly reflected a human eye condition. Although some models such as $EpiOcular^{TM}$, HCE model, LabCyte Cornea-Model, and MCTT $HCE^{TM}$ were already presented advanced cornea ex-vivo model to replace animal test. In this sense, cornea tissue structure mimicked ex-vivo toxicity model was fabricated in this study. The corneal epithelial cells (CECs) and keratocytes (CKs) isolated from rabbit eyeball were seeded on non-patterned silk film (n-pSF) and patterned silk film (pSF) at $32,500cells/cm^2$ and $6,500cells/cm^2$. Sequentially, n-pSF and pSF were stacked to mimic a multi-layered stroma structure. The thickness of films was about $15.63{\mu}m$ and the distance of patterns was about $3{\mu}m$. H&E stain was performed to confirm the cell proliferation on silk film. F-actin of CKs was also stained with Phalloidin to observe the cytoskeletal alignment along with patterns of the pSF. In the results, CECs and CKs were shown the good cell attachment on the n-pSF and pSFs. Proliferated cells expressed the specific phenotype of cornea epithelium and stroma. In conclusion, we successfully established the ex-vivo cornea toxicity model to replace the eye irritation tests. In further study, we will set up the human ex-vivo cornea toxicity model and then will evaluate the drug screening efficacy.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.15-16
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• 2008

This paper describes the on-site PSS Tuning Test of EX2000 excitation of Dangin T/P #4. The on-line 2% AVR step test in 500MW was performed by setting PSS gain from 0 to 15 by 3 increasement. The time-domain measured data was also analyzed by DFT analysis. Finally, the measured data was replicated and verified by running the time-domain dynamic simulation.

• Journal of Species Research
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• 제9권3호
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• pp.210-217
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• 2020

Microseira wollei (Farlow ex Gomont) G.B.McGregor and Sendall ex Kennis, a mat-forming filamentous harmful cyanobacterium, has historically been found in the United States. Microseira wollei produces neurotoxins and hepatotoxins which affect declining water quality. In the present research, we report of unrecorded M. wollei with morphology, TEM anatomy, molecular phylogeny on the Korean population. Based on 16S rRNA gene sequences, Korean population were different by 0.02% (2 bp) to the Japanese population, 1.2-1.3% to the Australian population, and 2.5-3.7% to the United States populations. nifH gene sequences were 8.4-8.7% different to Australian ones and 3.5-3.8% to other population, however molecular phylogenetic analysis of M. wollei living in Korea revealed monophyly with the geographical populations of U.S.A., Australia, and other geographical populations. Since the mat of M. wollei has been reported to be maintained for several years in other countries, it is necessary further investigate the seasonal and regional distribution of this species in Korea.

• 한국자기학회지
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• 제9권4호
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• pp.196-202
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• 1999

본 연구에서는 마그네트론 스퍼터링 법으로 제작한 Mn-Ir/Ni-Fe/Buffer/Si 다층막에서 다양한 하지층과 적층구조에 따른 교환이방성과 미세구조에 대하여 고찰하였다. Ni-Fe 위에 Mn-Ir을 증착한 Top 구조의 경우에서는 (111) 우선방위에 상관없이 165 Oe 이상의 높은 Hex 값을 얻을수 있었다. 또한 Mn-Ir/Ni-Fe 계면에서 grain-to-grain epitaxy가 발생함을 알 수 있었다. 따라서 Mn-Ir/Ni-Fe 다층박막의 Hex는 Mn-Ir/Ni-Fe 계면에서의 Mn-Ir의 결정립 크기와 grain-to-grain epitaxy에 의존하며 Hc는 Mn-Ir/Ni-Fe의 계면거칠기에 의존한다는 것을 알 수 있었다.

• Molecules and Cells
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• 제42권6호
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• pp.460-469
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• 2019

Bacterial ${\alpha}-type$ carbonic anhydrase (${\alpha}-CA$) is a zinc metalloenzyme that catalyzes the reversible and extremely rapid interconversion of carbon dioxide to bicarbonate. In this study, we report the first crystal structure of a hyperthermostable ${\alpha}-CA$ from Persephonella marina EX-H1 (pmCA) in the absence and presence of competitive inhibitor, acetazolamide. The structure reveals a compactly folded pmCA homodimer in which each monomer consists of a 10-stranded ${\beta}-sheet$ in the center. The catalytic zinc ion is coordinated by three highly conserved histidine residues with an exchangeable fourth ligand (a water molecule, a bicarbonate anion, or the sulfonamide group of acetazolamide). Together with an intramolecular disulfide bond, extensive interfacial networks of hydrogen bonds, ionic and hydrophobic interactions stabilize the dimeric structure and are likely responsible for the high thermal stability. We also identified novel binding sites for calcium ions at the crystallographic interface, which serve as molecular glue linking negatively charged and otherwise repulsive surfaces. Furthermore, this large negatively charged patch appears to further increase the thermostability at alkaline pH range via favorable charge-charge interactions between pmCA and solvent molecules. These findings may assist development of novel ${\alpha}-CAs$ with improved thermal and/or alkaline stability for applications such as $CO_2$ capture and sequestration.

• 한국표면공학회지
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• 제26권1호
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• pp.3-9
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• 1993

Chemical vapor deposited tungsten films were formed in a cold wall reactor at pressures higher (10~120torr) than those conventionally employed (<1torr). SiH4, in addition to H2, was used as the reduction gas. The effects of pressure and reaction temperature on the deposition rate and morphology of the films were ex-amined under the above conditions. No encroachment or silicon consumption was observed in the tungsten de-posited specimens. A high deposition rate of tungsten and a good step coverage of the deposited films were ob-tained at 40~80 torr and at a temperature range of $360~380^{\circ}C$. The surface roughness and the resistivity of the deposited film increased with pressure. The deposition rate of tungsten increased with the total pressure in the reaction chamber when the pressure was below 40 torr, whereas it decreased when the total pressure ex-ceedeed 40 torr. The deposition rate also showed a maximum value at $360^{\circ}C$ regardless of the gas pressure in the chamber. The results suggest that the deposition mechanism varies with pressure and temperature, the surface reac-tion determines the overall reaction rate and (2) at higher pressures(>40 torr) or temperatures(>36$0^{\circ}C$), the rate is controlled by the dtransportation rate of reactive gas molecules. It was shown from XRD analysis that WSi2 and metastable $\beta$-W were also formed in addition to W by reactions between WF6 and SiH4.

• BMB Reports
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• 제44권4호
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• pp.244-249
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• 2011

The quality of a phage-displayed antibody library deteriorates with clonal variations, which are caused by differentially expressed Escherichia coli antibody genes. Using the human Fab SP114 against the pyruvate dehydrogenase complex-E2 (PDCE2), we created four E. coli TOP10F' clones with a pCMTG phagemid encoding Fab-pIII (pCMTG-Fab), Fd ($V_H+C_{H1}$)-pIII (pCMTG-Fd), or light chain (L) (pCMTG-L), or the vector only (pCMTG-${\Delta}Fab$) to investigate the effect of clonal variations in a defined manner. Compared to the others, the E. coli clone with pCMTG-Fab was growth retarded in liquid culture, but efficiently produced phage progenies by Ex12 helper phage superinfection. Our results suggest that an antibody library must be cultured for a short duration before helper phage superinfection, and that the Ex12 helper phage helped to alleviate the detrimental effect of clonal variation, at least in part, by preferentially increasing functional phage antibodies during phage amplification.

• 한국환경복원기술학회지
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• 제10권5호
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• pp.31-39
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• 2007

This study was carried out to evaluation the recycled waste soils from construction site for planting soil. For this purpose, the concentrations of polluted materials and the physico-chemical properties were measured at recycled soil samples of an industrial waste treating company in the Metropolitan landfill area. The concentrations of polluted materials did not exceed to the standard critical levels of soil pollution in all analyzed items. The measures of the samples soil texture (loamy sand), bulk density (1.09~1.32g/$cm^3$), saturated hydraulic conductivity ($1.6{\times}10^{-3}{\sim}1.8{\times}10^{-3}$cm/sec), solid phase distribution (0.4~0.5$m^3/m^3$), porosity (0.5~0.6$m^3/m^3$), Ex. $K^+$ (1.0~1.2cmol/kg), Ex. $Mg^{2+}$ (0.2~0.6cmol/kg) were identified as not worse than those of conventional planting soil. But the sample soils have serious problems for planting soil such as high levels of pH (9.6~11.5), EC (0.78~1.84ds/m) and Ex. $Ca^{2+}$ (25.6~34.5cmol/kg), low level of organic matter (0.2~0.3%). It is required to improve pH, EC and Ex. $Ca^{2+}$ of sample soils. Consequently, the results suggested a high potential of recycling of the wastes soils for planting soil.

• 한국조경학회지
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• 제26권2호
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• pp.91-100
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• 1998

This paper is to study on rating system of some shrubs for pedestrian control with concentrate upon the density of branch. It was usd that Hibiscus syricacus L., Spiraea prunifolia var. simpliciflora Nak, Ligustrum obtusifolium S. et Z., Callicarpa dichotoma Raeusch., Rhoododendron mucrionulatum Turcz., Syringa vulgaris L., Weigela subsessilis L. H. Bailey, Cercis chinensis bunge, Forsythia koreana Nak., Euonymus alatus Sieb, Chaenomeles speciosa Nak., orbaria sorbifolia var. stellipila Max., Deutzia parviflora Bunge, Kerria japonica De Candolle, Prunus tomentosa Thunberg ex Murray, Purunus grandulosa for. albiplena Koehne. Shrubs are invesitgated ito the density of branch, the power of sprout, height, a rate of growth, hardness of naturalizaton, crown width and existence of thorns. Shrubs belonged to high group of rating system for pedestrian control were Euonymus alatus Sieb, Purunus grandulosa for. albiplena Koehne, Chaenomeles speciosa Nak., Spiraea prunifolia var. simpliciflora Nak., Prunus tomentosa Thunberg ex Murray, Rhododendron mucronulatum Turcz., Hibiscus syricacus L., Ligustrum obtusifolium S. et Z., Syringa vulgaris L., Weigela subsessilis L.H.Bailey.