• Food Science of Animal Resources
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• v.37 no.6
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• pp.940-947
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• 2017

Goat milk has a protein composition similar to that of breast milk and contains abundant nutrients, but its use in functional foods is rather limited in comparison to milk from other sources. The aim of this study was to prepare a goat A2 ${\beta}$-casein fraction with improved digestibility and hypoallergenic properties. We investigated the optimal conditions for the separation of A2 ${\beta}$-casein fraction from goat milk by pH adjustment to pH 4.4 and treating the casein suspension with calcium chloride (0.05 M for 1 h at $25^{\circ}C$). Selective reduction of ${\beta}$- lactoglobulin and ${\alpha}_s$-casein was confirmed using sodium dodecyl sulphate-polyacrylamide gel electrophoresis and reverse-phase high-performance liquid chromatography. The hypoallergenic property of A2 ${\beta}$-casein fraction was examined by measuring the release of histamine and tumor necrosis factor alpha from HMC-1 human mast cells exposed to different proteins, including A2 ${\beta}$-casein fraction. There was no significant difference in levels of both indicators between A2 ${\beta}$-casein treatment and the control (no protein treatment). The A2 ${\beta}$-casein fraction is abundant in essential amino acids, especially, branched-chain amino acids (leucine, valine, and isoleucine). The physicochemical properties of A2 ${\beta}$-casein fraction, including protein solubility and viscosity, are similar to those of bovine whole casein which is widely used as a protein source in various foods. Therefore, the goat A2 ${\beta}$-casein fraction may be useful as a food material with good digestibility and hypoallergenic properties for infants, the elderly, and people with metabolic disorders.

• Journal of Korean Neurosurgical Society
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• v.63 no.6
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• pp.698-706
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• 2020

Objective : To study the physiochemical characteristics of podophyllotoxin (PPT) conjugated stearic acid grafted chitosan oligosaccharide micelle (PPT-CSO-SA), and evaluate the ability of the potential antineoplastic effects against glioma cells. Methods : PPT-CSO-SA was prepared by a dialysis method. The quality of PPT-CSO-SA including micellar size, zeta potential, drug encapsulation efficiency and drug release profiles was evaluated. Glioma cells were cultured and treated with PPT and PPT-CSO-SA. The ability of glioma cells to uptake PPT-CSO-SA was observed. The proliferation of glioma cells was determined by 3-[4, 5-dimethyl-2-thiazolyl]-2, 5-diphenyl-2H-tetrazolium bromide (MTT) assay. The apoptosis and morphology of U251 cells were observed by 4',6-Diamidino-2-phenylindole dihydrochloride (DAPI) dye staining. Cell cycle analysis was performed by flow cytometry. The migration ability of U251 cells was determined by wound healing test. Results : PPT-CSO-SA had nano-level particle size and sustained release property. The encapsulation efficiency of drug reached a high level. The cellular uptake percentage of PPT in glioma cells was lower than that of PPT-CSO-SA (p<0.05). The inhibitory effect of PPT-CSO-SA on glioma cells proliferation was significantly stronger than that of PPT (p<0.05). The morphologic change of apoptosis cell such as shrinkage, karyorrhexis and karyopyknosis were observed. The percentage of U251 cells in G2/M phase increased significantly in the PPT-CSO-SA group compared with PPT group (p<0.05). Compared with the PPT group, the cell migration ability of the PPT-CSO-SA group was significantly inhibited after 12 and 24 hours (p<0.05). Conclusion : PPT-CSO-SA can effectively enhance the glioma cellular uptake of drugs, inhibit glioma cells proliferation and migration, induce G2/M phase arrest of them, and promote their apoptosis. It may be a promising anti-glioma nano-drug.

• Applied Chemistry for Engineering
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• v.18 no.4
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• pp.376-380
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• 2007

Used polyurethane (PU) was chemically degraded by the treatment with flame retardants such as tris(1,3-chloro-2-propyl) phosphate (TCPP), triethyl phosphate (TEP), and trimethyl phosphate (TMP). Analysis of FT-IR and P-NMR showed that the degraded products (DEP) contained oligourethanes. Rigid polyurethane foam was produced using the DEP as flame retardants. The flammability and thermal stability of recycled rigid polyurethane were investigated. The mechanical properties such as compressive strength of recycled polyurethane were also studied. The recycled polyurethane reduced flammability and enhanced thermal stability over intrinsic polyurethane. Mechanical strength of recycled polyurethane also shows as high as that of intrinsic polyurethane. In order to evaluate flame retardant properties of the recycled polyurethane foams with various amounts of DEP, heat release rate (HRR) of the foam was measured by cone calorimeter. Scanning electron micrograph of recycled PU showed a uniform cell morphology as a intrinsic PU.

• Journal of the Korea Concrete Institute
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• v.24 no.2
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• pp.173-183
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• 2012

Recently, experimental studies to prevent explosive spalling based on spalling mechanism and addition of Polypropylene fiber in high strength concrete (HSC) are performed actively. However, with respect to ultra high strength concrete (UHSC), its compact internal structure is more difficult release vapor pressure at rapid rising temperature compared to HSC. Therefore, in this study, an experiment was conducted to evaluate spalling properties of UHSC using ${\Box}$ $100mm{\times}100{\times}H200mm$ rectangular specimen according to ISO-834 standard fire curve. With respect melting point of fiber, three fiber types of Polyethylene, Polypropylene, and Nylon fibers with melting temperature of $110^{\circ}C$, $165^{\circ}C$, and $225^{\circ}C$, respectively, were considered. Mixed fiber of 0.15% and 0.25% of concrete volume was used to consider spalling properties based on water vapor pressure release. Then, TGDTA test on fiber and FEM analysis were performed. The results showed that it is difficult to prevent initial spalling without loss of fiber mass even if fiber melting temperature is low. Also, in preventing thermal spalling, fiber that melts to rapidly create porosity within 10 minutes of fire is more effective than that of low melting temperature property of fiber.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.2
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• pp.264-279
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• 2005

Statement of problem. Intraoral corrosion not only affects the esthetic and function of metallic dental restoration, but also has biologic consequences as well. Therefore, corrosion is considered a primary factor when choosing the dental alloy and laboratory technique. Purpose. The objective of this study was to compare the effects of solder and laser weld on corrosion Material and methods. Test specimens were made of 2 types of gold alloys, Co-Cr and Ni-Cr alloy and fabricated 3 methods, respectively: as cast, solder, and laser weld. For the analysis of corroding properties, potentiodynamic polarization test and immersion test conducted. The potentiodynamic polarization scan curve were recorded in 0.9% NaCl solution(pH 7) using Potentiostat/Galyanostat Model 273A. All specimens were exposed to 0.9% NaCl solution(pH 2.3) during 14 days. Elemental release into corrosive solution was measured by atomic emission spectrometry Differences in corrosion potential and mass release were determined using ANOVA. Results and conclusion. Through analyses of the data, following results were obtained. 1. In Pontor MPF and Wiron 99, corrosion potential of the solder group was statistically lower than as cast and laser weld group (p<0.05) , but there was no difference between corrosion potential of solder group and laser weld group in Pontor MPF and no differences between as cast and laser weld group (p>0.05). In Jel-Bios 10 and Wirobond, there was no difference of corrosion potential according to joining methods(p>0.05). 2. In all tested alloys, the amount of released metallic ion was greatest in the solder group(p<0.05). There was no difference between as cast group and laser weld group in Jel-Bios 10 and Wirobond(p>0.05). 3. In scanning electron microscopic examination. except soldered Wiron 99 specimens, it is impossible to discriminate the corrosive property of solder and laser weld. 4. Under the this experimental circumstances, laser weld appears superior to the solder when corrosion is considered.

• The Korea Journal of Herbology
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• v.29 no.4
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• pp.83-89
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• 2014

Objectives : The purpose of this study was to investigate effects of Houttuyniae Herba water extract (HC) on calcium release and production of various inflammatory mediators such as nitric oxide (NO), interferon-inducible protein (IP)-10, platelet derived growth factor (PDGF)-BB, keratinocyte-derived chemokine (KC), vascular endothelial growth factor (VEGF), interleukin (IL)-4, and IL-5 in lipopolysaccharide (LPS)-induced RAW 264.7 mouse macrophages. Methods : NO production was measured by Griess reagent assay. Intracellular calcium level was measured with Fluo-4 assay. Levels of cytokines were measured by High-throughput multiplex bead array cytokine assay based on xMAP (multi-analyte profiling beads) technology. Results : HC significantly decreased NO production for 24 hrs incubation at the concentrations of 10, 25, 50, 100, and $200{\mu}/mL$ in LPS-induced RAW 264.7 (P < 0.05). HC significantly decreased production of IP-10, KC, VEGF, and PDGF-BB for 24 hrs incubation at the concentrations of 50, 100, and $200{\mu}/mL$ in LPS-induced RAW 264.7 (P < 0.05). HC also significantly decreased intracellular calcium release for 24 hrs incubation at the concentrations of 25, 50, 100, and $200{\mu}/mL$ in LPS-induced RAW 264.7 (P < 0.05). But HC did not show any significant effect on production of IL-4 and IL-5 in LPS-induced RAW 264.7. Conclusions : The results suggested that HC has anti-inflammatory property related with its inhibition on the production of NO, IP-10, KC, VEGF, and PDGF-BB in LPS-induced macrophages via calcium pathway.

• Polymer(Korea)
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• v.39 no.1
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• pp.23-32
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• 2015

Phase change materials based on ultra high molecular weight of polyethylene (UHMWPE) blended with paraffin wax (mp $65^{\circ}C$) were studied in this paper. In addition, this paper reviews recent studies on the preparation of shape stabilized phase change materials (SSPCM), such as SSPCM from UHMWPE and paraffin wax (mp $65^{\circ}C$), their basic properties and possible applications to latent heat storage. The preparation method was an absorption method. Also, SSPCM composites were prepared by using a hot press at $200^{\circ}C$ for 10 min. The analysis for the shape ability of SSPCM to improve heat efficiency was measured by FTIR, SEM, DSC, XRD, and ARES. UHMWPE composites with 30 wt% paraffin wax (mp $65^{\circ}C$) demonstrated less deterioration of physical property and effective thermal property compared with other conditions. As a result, these SSPCMs could be used for the heat storage and release materials for various products.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.404-409
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• 2017

Natural polymer chitosan has been widely applied to medical fields due to its biochemical activities such as anticancer, antibacterial and lowering cholesterol in addition to biocompatibility and biodegradability. Currently, researches are being actively conducted to develop various drug-encapsulated chitosan nanoparticles for curing different diseases by applying chitosan to a drug delivery system. The free amine ($-NH_2$) group present in chitosan can bind to various hydrophobic groups by physical and chemical modification and the chitosan with hydrophobic groups can form shell-core nanoparticles by self-assembly when dispersed in water. In addition, an insoluble drug can increase the solubility against water when it was encapsulated in the core of chitosan nanoparticles. Also, the therapy effect can be maximized by minimizing side effects of drugs such as proteins, anticancer drugs and vaccines when they were encapsulated in the core of chitosan nanoparticles. Moreover, it is possible to control the particle size and release rate according to the hydrophobic group introduced to chitosan, so that it can be applied to a wide range of medical fields. The purpose of this review is to discuss the preparation and property of chitosan nanoparticles modified with various hydrophobic groups, and the application to drug delivery systems according to their property.

• Journal of the Korean Wood Science and Technology
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• v.48 no.4
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• pp.431-449
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• 2020

Structural property of most hydrogels is soft, resulting in low mechanical performance that limits their usage in the biomedical applications. For overcoming the drawback, cellulose nanocrystals (CNCs) were adopted in this study. Effects of CNCs on characteristics and drug delivery performance of poly (vinyl alcohol) based hydrogels were explored. FT-IR results showed that the fabricated hydrogels had semi-IPN (semi-interpenetrating polymer network) by formation of acetal and aldehyde bridge. Water absorption and swelling ratio decreased with increasing CNCs content, and the hydrogels with CNCs showed better viscoelastic performance than the without CNCs. Also, CNCs mostly improved the ability of the hydrogel to absorb the drug and the sustainability of the drug release. These results demonstrated that incorporating CNCs into the hydrogel systems can be a good alternative to improve drug delivery performance and mechanical property of the hydrogels.

• Polymer(Korea)
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• v.29 no.6
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• pp.599-604
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• 2005

The hyaluronic acid (HA) with excellent biocompatibility has been combined with lactide, the ester dimer of polylactide, with good biodegradability to produce biocompatible materials which can control the period of degradation in a human body. By freeze frying method, HA and lactide were crosslinked with crosslinking agent, 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC). Degree of lactide and EDC reaction was determined by the analysis of nuclear magnetic resonance spectroscopy. Both lactyl group and EDC conversion increased as the mole ratio of lactide to HA increased from 5 to 13. The membrane swelled less and became more brittle with the more addition of lactyl group resulting from the higher mole ratio of lactide to HA. Swelling ratio decreased and tensile modulus increased due to the more addition of lactyl group as the EDC concentration increased or reaction temperature decreased. Drug release experiment from various membranes with different degree of crosslinking showed that permeability decreased with increasing degree of crosslinking. The degradation became slower with the more addition of lactyl group. Mechanical property and degradation rate of the synthesized membrane were shown to be controlled through adjusting operation parameters such as mole ratio, temperature, and crosslinking agent concentration.