• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.487-497
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• 2020

The study examined the effects, strength, and weakness of chemical peeling and physical peeling, which are some types of peelings that are commonly used for cosmetic skin management for women. For this study, of which the study period was from November 1 to December 27, 2011, 20 female subjects with the compound skin type were investigated. Ten women were assigned to the chemical peeling group, and the other 10 were assigned to the physical peeling group. The experiment continued for six weeks, with one test session per week, totaling six tests. During each session, a skin measurement instrument was used to measure the oil, keratin, pore, wrinkles, and pigments. The results of the tests showed that, in the case of chemical peeling, both glycolic acid peeling and lactic acid peeling were effective in preserving the skin moisture. With physical peelings, crystal peeling was more effective on wrinkles, while diamond peeling was more effective in keratin and pigment improvement. A comparison of the peeling with different media revealed physical peelings to have more effect on more items, but chemical peeling was more effective in moisture and oil changes.

• Journal of Pharmaceutical Investigation
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• v.25 no.3
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• pp.33-35
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• 1995

Microspheres containing tetracaine or bupivacaine with poly-lactic-glycolic acid were prepared with a range of compositions. Using the rat scicatic nerve model in vivo it was found that prolonged blockade for periods of 2-7 days. depending on composition variables. Polymer-local anesthetics microspheres are feasible delivery vehicle for prolonged regional nerve blockade.

• Proceedings of the PSK Conference
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• 2000.04a
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• pp.216.2-216.2
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• 2000

• Journal of Pharmaceutical Investigation
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• v.39 no.3
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• pp.167-171
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• 2009

Poly(lactic-co-glycolic acid) (PLGA) microspheres have been a useful tool as a controlled drug delivery system for peptides and proteins. Recently, porous microspheres have gained great attention as inhalation drug delivery system due to their low aerodynamic densities. Here, we report highly porous PLGA microspheres, which were prepared by using a single o/w emulsification/solvent evaporation method. Two types of porogen, i.e., (i) extractable Pluronic F127 and (ii) gas foaming salt of ammonium bicarbonate, were used to induce pores on the surface of PLGA microspheres. The respective preparation conditions on dp/cp ratio and porogen concentration were determined by the previous preliminary experiments, and other preparation factors were further optimized on the basis of PLGA Mw and porogen type. The morphological features examined by scanning electron microscope (SEM) show these porous microspheres have highly porous surface structure with a diameter range of 20${\sim}$30 ${\mu}$m. These highly porous PLGA microspheres, which have much lower density, would be a practical aerosol system for pulmonary drug delivery.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1465-1470
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• 2011

In this study, a poly(lactic-co-glycolic acid) (PLGA) microspheres was fabricated using emulsion solvent evaporation technique. During the procedure fabrication, some parameters process have effected on the formation of micro-carriers. The structure and morphology of micro-carriers were evaluated by SEM observation. Beside, heparin incorporated into microspheres was determined using toluidine blue method. Specifically, the effects of some parameters process such as ultrasonic levels, PLGA concentrations and freeze-dry times on the size, structure, porous formation and heparin entrapment of micro-carriers were studied carefully. We found that, the morphology and structure of carriers were influenced by the all above parameters. The diameter of the carriers varied from 20 to 400 ${\mu}M$ depending on experimental conditions. At suitable freeze-dry time, the pores were automatically formation on surface of microspheres with a significantly in the numbers of pore. After heparin incorporated porous PLGA microspheres, it was suggested that the highly heparin incorporated into porous PLGA microspheres could enhance of angiogenesis for tissue regeneration easily.

• Journal of Microbiology and Biotechnology
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• v.27 no.4
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• pp.768-774
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• 2017

Horseradish peroxidase (HRP) catalyzes the oxidation of aromatic compounds by hydrogen peroxide via insoluble polymer formation, which can be precipitated from the wastewater. For HRP immobilization, poly(lactic-co-glycolic acid) (PLGA) fine carrier supports were produced by using the Nano Spray Dryer B-90. Immobilized HRP was used to remove the persistent 2,4-dichlorophenol from model wastewater. Both extracted (9-16 U/g) and purified HRP (11-25 U/g) retained their activity to a high extent after crosslinking to the PLGA particles. The immobilized enzyme activity was substantially higher in both the acidic and the alkaline pH regions compared with the free enzyme. Optimally, 98% of the 2,4-dichlorophenol could be eliminated using immobilized HRP due to catalytic removal and partly to adsorption on the carrier supports. Immobilized enzyme kinetics for 2,4-dichlorophenol elimination was studied for the first time, and it could be concluded that competitive product inhibition took place.

• Elastomers and Composites
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• v.33 no.3
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• pp.177-184
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• 1998

Polyurethane(PU) prepolymers were synthesized from polytetramethylene ether glycol(PTMG), with 4,4'-diphenylmethane diisocyanate(MDI), toluene 2,4-diisocyanate (TDI) and isophoron diisocyanate(IPDI). After chain extention using n-methyl-diethanol amine(n-MDEA), aqueous polyurethane cationomers were prepared by addition of glycolic acid(GA) as a quaternizer. The effect of the content of chain extender and the degree of neutralization on the stability of emulsion, adhesive strength, viscosity, glass transition temperature and physical properties of emulsion cast film were investigated using UTM, viscometer and DSC.

• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.195-204
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• 2013

While structured packing modules are known to be efficient for surface wetting and gas-liquid exchange in abiotic surface catalysis, this model study explores structured packing as a growth surface for catalytic biofilms. Microbial biofilms have been proposed as selfimmobilized and self-regenerating catalysts for the production of chemicals. A concern is that the complex and dynamic nature of biofilms may cause fluctuations in their catalytic performance over time or may affect process reproducibility. An aerated continuous trickle-bed biofilm reactor system was designed with a 3 L structured packing, liquid recycling and pH control. Pseudomonas diminuta established a biofilm on the stainless steel structured packing with a specific surface area of 500 $m^2m^{-3}$ and catalyzed the oxidation of ethylene glycol to glycolic acid for over two months of continuous operation. A steady-state productivity of up to 1.6 $gl^{-1}h^{-1}$ was achieved at a dilution rate of 0.33 $h^{-1}$. Process reproducibility between three independent runs was excellent, despite process interruptions and activity variations in cultures grown from biofilm effluent cells. The results demonstrate the robustness of a catalytic biofilm on structured packing, despite its dynamic nature. Implementation is recommended for whole-cell processes that require efficient gas-liquid exchange, catalyst retention for continuous operation, or improved catalyst stability.

• Macromolecular Research
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• v.15 no.3
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• pp.238-243
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• 2007

Nanofibers were prepared by electrospinning a solution of poly(lactic-co-glycolic acid) (PLGA) and their mean diameter was 340 nm. The PLGA nanofibers were treated with a plasma in the presence of either oxygen or ammonia gas to change their surface characteristics. The hydrophilicity of the electrospun PLGA nanofibers was significantly increased by the gas plasma treatment, as confirmed by contact angle measurements. XPS analysis demonstrated that the chemical composition of the PLGA nanofiber surface was influenced by the plasma treatment, resulting in an increase in the number of polar groups, which contributed to the enhanced surface hydrophilicity. The degradation behavior of the PLGA nanofibers was accelerated by the plasma treatment, and the adhesion and proliferation of mouse fibroblasts on the plasma-treated nanofibers were significantly enhanced. This approach to controlling the surface characteristics of nanofibers prepared from biocompatible polymers could be useful in the development of novel polymeric scaffolds for tissue engineering.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.2
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• pp.158-165
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• 2010

Purpose: The objective of the present study was to histologically evaluate durability and bone regeneration capacity of new synthetic membranes in comparison to clinically available collagen membrane. Material and methods: To the skulls of 12 rabbits, we created 4 bone defects of 6 mm in diameter on each of them. Each of defects were covered with at least one of 5 membranes; No membrane, Collagen ($Ossix^{TM}$), PLGA, HA-coated-PLGA and HA-PLGA/PLGA. After 4, 8, 12 weeks, we cut the skulls and dyed with H-E. And then, the histologic observation was done. Results: In current study, the control group which did not use the membrane showed bone regeneration at 12 weeks and covered the bone defect partially. New bones were formed through the underneath of endocranium, and the upper defect was filled with connective tissues and fats. Collagen membrane ($Ossix^{TM}$) showed new bones after 4 weeks, and they were formed through the membrane which maintained until 12 weeks. PLGA, HA-coated-PLGA, HA-PLGA/PLGA showed bone regeneration after 4 weeks and after 8 weeks, they mostly filled defects. At 12 weeks, we could find new bones and previous bones almost look alike and also, they united well. Membranes were unnoticeable after 4 weeks and were absorbed. Conclusion: Bone formation and maturation of PLGA, HA-coated-PLGA and HA-PLGA/PLGA were faster than the control group. They showed no difference on the application of HA and after 4 weeks, they were absorbed.