• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.514-517
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• 2011

Herein, we fabricated magnesium oxalate nanostructures by chemical etching of a magnesium foil in alcoholic solvents containing acidic media. Interestingly, we could obtain magnesium oxalate nanowires in ethanolic oxalic acid. Growth mechanism for magnesium oxalate nanowires was investigated in terms of etching time. Annealing conditions were determined from TGA results. Magnesium oxalate nanowires were converted to magnesium oxide nanowires by thermal treatment and the magnesium oxide nanowires were examined by FE-SEM and FT-IR measurement.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.69-76
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• 1982

The purpose of this study was to evaluate the color penetration of cavity margin with composite resin restorations in some Korean foods substance-soy sauce and hot bean paste. Fifty specimans which were extracted caries free third molar of young adults recently. All of the prepared 100 cavities were filled with two kinds of composite resin (Hipol$^{(R)}$and Restodent$^{(R)}$). The experimental specimans were divided into five groups by the following procedures. Group I : Filling of composite resin and polishing. Group II : Filling, polishing, etching of cavity and sealing. Group III : Etching, sealing, filling and polishing. Group IV : Etching, sealing, filling, polishing, and repeated of etching of cavity margin and sealing. Group V : Etching, sealing, filling, polishing, and sealing again without etching. Before examination, the restorated teeth were subjected to thermal cycling ($4^{\circ}C$ and $60^{\circ}C$). All the specimens were immersed in soy and 30% hot bean paste solution under $37^{\circ}C$ incubator during six weeks. Then, the specimens were sectioned bucco-lingually through the center of two restorations with diamond disk and examined under a. metallographic microscope. (Union 6617 U.S.A.) Thereafter, the degree of color penetration was calculated and analyzed. The obtained results were as follows: 1. The color penetration was the lowest in the procedure of Group III which was acid etching, sealing, composite resing filling, and polishing. 2. The color penetration occured in soy and hot bean paste, but the degree of penetration was not so significant statistically between them. 3. The degree of color penetration was not so significant statistically between Hipol$^{(R)}$ and Restondent$^{(R)}$.

• Restorative Dentistry and Endodontics
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• v.37 no.1
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• pp.9-15
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• 2012

Objectives: This study evaluated the effect of 2% chlorhexidine digluconate (CHX) with different application times on microtensile bonds strength (MTBS) to dentin in class I cavities and intended to search for ideal application time for a simplified bonding protocol. Materials and Methods: Flat dentinal surfaces with class I cavities ($4mm{\times}4mm{\times}2mm$) in 40 molar teeth were bonded with etch-and-rinse adhesive system, Adper Single Bond 2 (3M ESPE) after: (1) etching only as a control group; (2) etching + CHX 5 sec + rinsing; (3) etching + CHX 15 sec + rinsing; (4) etching + CHX 30 sec + rinsing; and (5) etching + CHX 60 sec + rinsing. Resin composite was builtup with Z-250 (3M ESPE) using a bulk method and polymerized for 40 sec. For each condition, half of the specimens were immediately submitted to MTBS test and the rest of them were assigned to thermocycling of 10,000 cycles between $5^{\circ}C$ and $55^{\circ}C$ before testing. The data were analyzed using two-way ANOVA, at a significance level of 95%. Results: There was no significant difference in bond strength between CHX pretreated group and control group at the immediate testing period. After thermocycling, all groups showed reduced bond strength irrespective of the CHX use. However, groups treated with CHX maintained significantly higher MTBS than control group (p < 0.05). In addition, CHX application time did not have any significant influence on the bond strength among groups treated with CHX. Conclusion: Application of 2% CHX for a short time period (5 sec) after etching with 37% phosphoric acid may be sufficient to preserve dentin bond strength.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.3
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• pp.299-306
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• 2018

The aim of this study was to evaluate the effect of etching time and bonding agents on bond strength of sealant applied to the occlusal surface of primary molars. Forty non-carious exfoliated human primary molars were included in the study. The teeth were randomly divided into 4 groups for measurement. For group I, no acid etching treatment was used. For group II, III, and IV, acid etching gels were applied on the occlusal surface for 15, 30, and 60 seconds, respectively. Each group was divided into 2 subgroups; one group was treated with bonding agents on the enamel while the other was not. Microtensile bond strength was evaluated using a universal testing machine. There were no statistically significant differences in bond strength with varying duration of etching among groups. The results revealed that the use of bonding agents prior to application of fissure sealant increased the bond strength(p < 0.05). It could be concluded that etching time greater than 15 seconds does not significantly enhance the bond strength, but the use of bonding agents as an intermediate layer between the primary molar and fissure sealant would be beneficial in increasing the bond strength.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.46-46
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• 1999

• The Journal of the Korean dental association
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• v.42 no.2 s.417
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• pp.94-100
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• 2004

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.06a
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• pp.36-36
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• 2001

• Proceedings of the Korean Vacuum Society Conference
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• 1997.02a
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• pp.54-55
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• 1997

• Corrosion Science and Technology
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• v.10 no.1
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• pp.37-42
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• 2011

Aluminum was electrochemically etched in acid solution and the surface area was magnified by the formation of etch pits. Etched aluminum was covered with a compact and dense dielectric oxide film by anodization and applied to the aluminum electrolytic capacitor electrode. Capacitance of aluminum electrolytic capacitor is closely related with surface area, which depends on size and number of etch pits. Size of etch pits need to be controlled because inside of the pits can be buried by the formation of dielectric oxide film. In this work, the effect of ultrasound pretreatment on the aluminum etch pit formation and capacitance were investigated. Additionally, the relationship between the second etching effect on pit size and capacitance was studied.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.855-859
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• 2012

Silicon nanowires (SiNWs) were fabricated by a metal-assisted chemical etching of Si and the porous structure on their surfaces was controlled by changing the volume ratio of the etching solution composed of hydrofluoric acid, hydrogen peroxide, and deionized water. The concentration of hydrogen peroxide as the oxidant was varied for controlling the porosity of SiNWs. The optical properties of porous SiNWs were unique and very different from those of single-crystalline Si, as characterized by measuring their photoluminescence and Raman spectra for different porosities.