• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.3
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• pp.381-390
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• 2004

The purpose of this in vitro study was to investigate the effects of Nd:YAG laser irradiation and fluorides on acid drink demineralized enamel. The materials were 30 freshly extracted permanent premolars with intact smooth enamel surfaces. They were demineralized with Coca-cola at $37^{\circ}C$ for 12hours and then irradiated by Nd:YAG laser with 6W power, $50mJ/cm^2$ energy density, and 20Hz pulse repetition. After laser irradiation, teeth were treated by three kinds of fluorides; (1)0.05% NaF fluoride solution (2)1.23% APF gel and (3)0.1%F fluoride varnish, microhardness(VHN) and Diagnodent scores were measured and the surfaces of each treated specimens were also observed with SEM under 1500 magnification. The results were as follows: 1. In the change of microhardness(VHN), it decreased to 34.68% from the initial micrhardness, increased to 78.37% after laser irradiation and increased to 82.62% after fluoride treatment, there were significant differences except when it was irradiated and treated with fluoride(P<0.05). 2. In the change of Diagnodent scores, it was decreased to 28.08% from the initial scores after demineralization, and then increased to 59.81% after laser irradiation, and increased to 82.17% after fluoride treatment. Scores were different significantly between the scores of initial, demineralization, laser irradiation and fluoride treatment(P<0.05). All the scores were not different significantly between fluoride types. 3. SEM observation showed that the lased enamel surfaces after demineralization were thermally degenerated and showed molten lava-like appearance and crater with cracks and many microholes.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.118-123
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• 2008

In the present study, the effect of oxyfluorination treatment on multi-walled nanotubes (MWNTs) supports was investigated by analyzing surface functional groups. The surface characteristics were determined by Fourier transformed-infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). After the deposition of platinum nanoparticles on the above treated carbon supports, a crystalline size and a loading level had been investigated. Electrochemical properties of the treated MWNTs-supported Pt (Pt/MWNTs) catalysts were analyzed by current-voltage curve measurements. From the results of surface analysis, an oxygen and fluorine-containing functional group had been introduced to the surface of carbon supports. The oxygen and fluorine contents were the highest value at the treatment of 100 temperature. The Pt/100-MWNTs showed the smallest particle crystalline size of 3.5 nm and the highest loading level of 9.4% at the treatment of 100 temperature. However, the sample treated at the higher temperature showed the larger crystalline size and the lower loading level. This indicated that the crystalline size and the loading level could be controlled by changing the temperature of oxyfluorination treatment. Accordingly, an electrochemical activity was enhanced by increasing the temperature of treatment upto 100, and then decreased in the case of 200 and 300. The highest specific current density of 120 mA/mg had been obtained in the case of Pt/100-MWNTs.

• The Journal of the Korea Contents Association
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• v.13 no.4
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• pp.312-319
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• 2013

The purpose of this study was to evaluate the efficacy of gargle and toothpaste containing low concentration with sodium fluoride on the remineralization through the surface microhardness and mineral content in enamel. After 4 weeks-application, the enamel surface was measured using microhardness tester and the calcium (Ca) and phosphorous (P) concentration of mineral content by electron probe microanalyzer (EPMA) analysis. By combining fluoridated gargle with toothpaste, a remineralized enamel resulted in significantly significant differences among the four groups (p<0.05). The Ca change treated with 0.23% fluoridated toothpaste and 0.02% fluoridated gargle with 0.23% toothpaste demonstrated the highest among the other groups. In conclusion. the fluoridated gargle with toothpaste by low concentration showed a significantly greatest synergistic effect on remineralization of the enamel than the other groups.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.2
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• pp.201-206
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• 2006

A recent laboratory study has demonstrated improved caries lesion resistance with enamel that was exposed to $CO_2$ laser irradiation for very short time period. When topical fluoride treatment was performed before or after laser irradiation, reductions in dental caries. The purpose of this scanning electron microscopic(SEM) study and atomic force microscope study was to characterize surface alterations in tooth enamel after in vitro laser irradiation alone and combined topical fluoride treatment either before or after laser irradiation. The treatment effects of laser irradiation led to the formation of an irregular, mild porosities and fine fissures, also created granular materials. But when laser irradiation was followed by APF, the enamel surface had homogenous architecture. The result led to the caries resistance effects by these granular structures have been considered to represent redeposited mineral phases due to the mobilization of calcium, phosphate, and fluoride from lased enamel.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.55-60
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• 2021

Fluorination was carried out to improve the adsorption performance of pitch-based activated carbon fibers (ACFs) onto acetic acid. Both plasma and direct gas fluorination were used for fluorination, and the acetic acid gas adsorption performance of fluorinated ACFs was investigated. X-ray photoelectron spectroscopy (XPS) is analyzed to determine the surface characteristics of ACFs, and the pore characteristics were analyzed by 77 K nitrogen adsorption. An adsorption performance was measured through gas chromatography, and it was confirmed that the breakthrough time of plasma fluorinated sample was 790 min and that the breakthrough time was delayed compared to that of using untreated one of 650 min. However, the breakthrough time of direct gas fluorinated sample was 390 min, indicating that the adsorption performance was inhibited. The plasma fluorinated ACFs showed an increase in the adsorption performance due to an electrostatic attraction between the acetic acid gas (CH3COOH) with the fluorine group introduced to the surface without changing its specific surface area. On the other hand, the specific surface area of the direct gas fluorinated ACFs decreased significantly up to 55%, and the physical adsorption effect on the acetic acid gas also reduced.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2003.10a
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• pp.67-68
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• 2003

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2003.10a
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• pp.92-93
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• 2003

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.638-644
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• 2017

Pitch based activated carbon fibers for electric double layer capacitor (EDLC) electrodes were treated by oxyfluorination via varying the ratio of fluorine and oxygen gases to improve high power property. As the partial pressure of fluorine increased, the oxyfluorinated activated carbon fibers showed an increase of linear fluorine functional groups. While the oxygen functional groups increased, no changes was observed with respect to the partial gas pressure. The specific surface area and pore volume decreased due to the etching reaction on the activated carbon fiber surface through oxyfluorination, but the mesopore volume increased about 4.5 times. In the case of activated carbon fibers treated with 50% of the fluorine gas partial pressure, the specific capacitance increased to about 29% and 61% at scan rates of 5 and 50 mV/s, respectively. The improvement of the specific capacitance was believed to be due to the introduction of oxygen and fluorine functional groups on the activated carbon fiber surface and the increase of mesopores through oxyfluorination.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.317-322
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• 2010

In this study, poly(methyl methacrylate) (PMMA) was treated with changing mixing ratios of $F_2$ and $O_2$ using oxyfluorination method for hydrophilic modification of PMMA film. For the characterizations of oxyfluorinated PMMA surface, contact angle, surface free energy, X-ray photoelectron spectroscopy (XPS) and optical transmittance (UV-vis) were carried out. After the oxyfluorination, PMMA surface became more hydrophilic showing the decrease of water contact angle from $69^{\circ}$ to $44^{\circ}$. So, surface free energy of oxyfluorinated PMMA film was increased from 46 to $58\;mN\;m^{-1}$. These results are attributed to hydrophilic functional groups such as hydroxyl group formed oxyfluorination method on the PMMA surface. From XPS results, it was confirmed that O/C concentration ratio on the surface of PMMA was increased, the amount of C-OH bonding which shows hydrophilicity was also largely increased from 6.7 to 24.8% with increasing fluorine partial-pressure via the oxyfluorination, The oxyfluorination conditions, room temperature, 1 bar with one mixture ratio of $F_2$ to $O_2$ had little influence on optical transmittance properties of PMMA film but enhanced its surface hydrophilicity. This result suggests that oxyfluorination method could be useful to change hydrophobic PMMA surface to hydrophilic.

• Polymer Science and Technology
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• v.13 no.6
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• pp.751-758
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• 2002