• Journal of dental hygiene science
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• v.9 no.2
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• pp.153-160
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• 2009

The purposed of this study was to investigate the effect of Gold bonding agent as intermediate layer between metal substrate and ceramic coating. Gold bonding agent used to seal off any surface porosity, to mask the greyish color of the metal, and to provide an underlying bright golden hue to the ceramic coverage. The adhesion between metal substrate and ceramic is related to diffusion of oxygen during ceramic firing. The oxide layer produced on non-precious alloy anti titanium was considered to have a potentially adverse effect on metal-ceramic bonding. The oxidation characteristics of titanium and non-precious alloys are the main problem. Every group were divided into test and control groups. Control groups are carried out process of degassing for product oxide layer. Au coating was applied on each Ni-Cr, Co-Cr alloys and cp-Ti specimens with difference surface condition or degassing. Specimens surfaces and cutting plane was characterized by SEM/EDS. Results suggested that Au coating is effective barriers to protect metal oxidation during ceramic firing.

• Journal of the Korean Chemical Society
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• v.67 no.2
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• pp.120-128
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• 2023

Osteoporosis is a disease that causes the weakening of bone by increasing porosity, which often results in fractures. Osteoporosis treatment measures include the use of Bisphosphonates and estrogen. However, these treatments cannot be used in the long term as these treatments have adverse side effects. Therefore, there is a need to identify better and safer treatment options. For this, 63 plant extracts were screened and among them, six extracts showed high anti-osteoclastic activity with low cytotoxicity. Of these six extracts, three extracts, Cudrania tricuspidata (P371), Ulmus davidiana var. japonica (P401), and Torilis japonica (P411), showed more than 50 percent osteoclast inhibition. While the remaining, Stewartia pseudocamellia extracts I and II (P370, P397) and Cuscuta chinensis (P418), showed moderate or between 40-50 percent osteoclast inhibition. Among all the extracts, Torilis japonica (P411) showed the highest inhibitory action against osteoclast development. Torilis japonica (P411) primary components include Kaempferol, Quercetin, and Luteolin, all proven to inhibit osteoclastogenesis. Stewartia pseudocamellia extracts I and II (P370 and P397) showed moderate or 44% osteoclast inhibition. Stewartia pseudocamellia extract II (P397) enhanced the growth of RAW 264.7 cells by 19%. Torilis japonica (P411) and Stewartia pseudocamellia extract II (P397) suppressed the expression of osteoclast-specific genes in RANKL-induced osteoclastogenesis in RAW 246.7 cells. Torilis japonica (P411) extracts even increased osteoblast-specific RUNX2 gene expression. This results provide that six extracts could be used as a potential treatment option for osteoporosis disease with the extracts of Torilis japonica (P411) and Stewartia pseudocamellia (P397) as an ideal candidates. However, the combination of the extract with higher osteoclastic inhibition and less toxic effects with further analysis should be recommended.

• Polymer(Korea)
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• v.38 no.5
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• pp.676-681
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• 2014

Licorice, widely used as a herbal medicine, has flavonoids such as liquiritin and its aglycone, liquiritigenin that show anti-oxidant and anti-inflammatory properties. Licorice flavonoid-loaded cellulose hydrogels were prepared as carriers for skin drug delivery, and their properties were investigated. The porous cellulose hydrogel was made by reacting cellulose with epichlorohydrin as a cross-linking agent in NaOH/urea(1~10%) solutions. Through studies on the rheological properties and water uptake of the hydrogel, a NaOH/urea(6%) solution was established as being optimum for the synthesis of the cellulose hydrogel containing liquiritin and liquiritigenin. Scanning electron microscopy (SEM) observations of a cross-section of the prepared hydrogel indicated its porosity. In particular, in skin permeation experiments using a Franz diffusion cell, hydrogel containing the licorice flavonoids showed remarkable transdermal permeation compared to the control group. These results indicate that porous cellulose hydrogel is a potential drug delivery system to enhance the skin permeation of licorice flavonoids.

• Journal of the Mineralogical Society of Korea
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• v.30 no.2
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• pp.71-81
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• 2017

Rock properties and the effects of chemicals that were used for conservation were studied for effective conservation treatment of Seated Buddha rock carving, which is composed of grayish white tuff, at Golguram Hermitage, Gyeongju. The rocks contain 3-5% montmorillonite, a swelling mineral and reacting with water, the d spacing of swelling minerals was increased (1.54-2.69%). On the one hand, the physical properties of the rock samples, such as surface hardness, water absorption rate, and porosity improved after the application of ethyl silicate-based stone strengthener. On the other, the interlayer of swelling minerals decreased and greater the of swelling mineral content, the greater is the extent of swelling (4.23-12.12%). When the ethyl silicate-based stone strengthener was applied after pretreatment with a swelling inhibitor, the physical properties were similar to those of the stone strengthener alone. There was no interlayer spacing change of swelling minerals due to swelling inhibition treatment; however, when the stone strengthener was applied after the swelling inhibitor, interlayer changes were similar to those when only the stone strengthener was treated (4.10-11.85%). Though the peak intensity of swelling minerals in X-ray diffraction pattern decreased, the effect of the swelling inhibitor was almost negligible. Therefore, it is not appropriate to use ethyl silicate-based stone strengthener for Golgulam rock containing swelling minerals and supplementing them with a swelling inhibition system is not effective. Because weathering rapidly progresses when swelling minerals contact moisture, for now, measures to prevent water contact, such as expansion of the canopy, are needed in the lower and side parts of the carving.

• Polymer(Korea)
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• v.34 no.4
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• pp.333-340
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• 2010

Zaltoprofen, a propionic acid derivative non-steroidal anti-inflammatory drug (NSAID), is known to have powerful inhibitory effects on acute, subacute and chronic inflammation. We developed poly(lactide-co-glycolide)(PLGA) microspheres loaded with zaltoprofen for sustained controlled delivery using an oil-water solvent evaporation methods by varying PLGA molecular weight and cosurfactant contents. Physicochemical properties and morphology of zaltoprofen-loaded PLGA microspheres were investigated by scanning electron microscope, X-ray diffraction and differential scanning calorimeter. The size of microspheres increased with the molecular weight of PLGA and the content of cosurfactants. The increase of PLGA molecular weight and cosurfactant content decreased the porosity of microspheres, subsequently resulting in the slow drug release. The results demonstrated that the adjustment of PLGA molecular weight and the cosurfactant content allowed us to control the drug release profiles of drug-loaded microspheres.

• Membrane Journal
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• v.33 no.4
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• pp.191-200
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• 2023

Polyethersulfone (PES) is a widely employed membrane material for water and industrial purification applications owing to its hydrophilicity and ease of phase separation. However, PES membranes and filters prepared using the nonsolvent induced phase separation method often encounter significant flux decline due to pore clogging and cake layer formation on the dense membrane surfaces. Our investigation revealed that tight microfiltration or loose ultrafiltration membranes can be subject to physical fouling due to the formation of a dense skin layer on the bottom side caused by water intrusion to the gap between the shrank membrane and the substrate. To investigate the effect of the bottom surface porosity on membrane fouling, two membranes with the same selective layers but different sub-layer structures were prepared using single and double layer casting methods, respectively. The double layered PES membrane with highly porous bottom surface showed high flux and physical fouling tolerance compared to the pristine single layer membrane. This study highlights the importance of physical optimization of the membrane structure to prevent membrane fouling.