• Applied Science and Convergence Technology
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• v.25 no.3
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• pp.51-55
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• 2016

The surface treatment of a titanium implant is investigated with a non-thermal atmospheric pressure plasma jet. The plasma jet is generated by the injection of He and $O_2$ gas mixture with a sinusoidal driving voltage of 3 kV or more and with a driving frequency of 20 kHz. The generated plasma plume has a length up to 35 mm from the jet outlet. The wettability of 4 different titanium surfaces with plasma treatments was measured by the contact angle analysis. The water contact angles were significantly reduced especially for $O_2/He$ mixture plasma, which was explained with the optical emission spectroscopy. Consequently, plasma treatment enhances wettability of the titanium surface significantly within the operation time of tens of seconds, which is practically helpful for tooth implantation.

• The Journal of Advanced Prosthodontics
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• v.9 no.2
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• pp.118-123
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• 2017

PURPOSE. To investigate the effect of non-thermal atmospheric pressure plasma (NTAPP) treatment on shear bond strength (SBS) between resin cement and colored zirconia made with metal chlorides. MATERIALS AND METHODS. 60 zirconia specimens were divided into 3 groups using coloring liquid. Each group was divided again into 2 sub-groups using plasma treatment; the experimental group was treated with plasma, and the control group was untreated. The sub-groups were: N (non-colored), C (0.1 wt% aqueous chromium chloride solution), M (0.1 wt% aqueous molybdenum chloride solution), NP (non-colored with plasma), CP (0.1 wt% aqueous chromium chloride solution with plasma), and MP (0.1 wt% aqueous molybdenum chloride solution with plasma). Composite resin cylinders were bonded to zirconia specimens with MDP-based resin cement, and SBS was measured using a universal testing machine. All data was analyzed statistically using a 2-way ANOVA test and a Tukey test. RESULTS. SBS significantly increased when specimens were treated with NTAPP regardless of coloring (P<.001). Colored zirconia containing molybdenum showed the highest value of SBS, regardless of NTAPP. The molybdenum group showed the highest SBS, whereas the chromium group showed the lowest. CONCLUSION. NTAPP may increase the SBS of colored zirconia and resin cement. The NTAPP effect on SBS is not influenced by the presence of zirconia coloring.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.337-337
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• 2011

Application of plasma technology on microbial sterilization has been frequently studied. In spite of accumulating number of studies, many have been focused on bacteria. Reports on eukaryotic yeasts and filamentous fungi are limited. In addition, mechanism of plasma effect still needs to be clarified. In this study, we analyzed the effect of non-thermal atmospheric pressure plasma on the budding yeast, Saccharomyces cerevisiae using DBD-type device. When yeast cells were exposed to plasma (at 2 mm distance) and then cultured on YPD-agar plate, number of cells survived (shown as colony) were reduced proportionally to exposure time. More than 50% reduction in number of colonies were observed after twice exposure of 5min. each. Colonies much smaller than those of control (no plasma exposure) were appeared after twice exposure of 5 min. each. It seems that small colonies are resulted from delayed cell growth due to the damage caused by plasma treatment. Microscopic analysis demonstrates that yeast cells treated with plasma for 5 min. twice have more rough and shrinked shape compared to oval shape with smooth surface of control.

• Food Science and Preservation
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• v.23 no.7
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• pp.960-966
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• 2016

This study was conducted to explore the potential for use of atmospheric pressure dielectric barrier discharge plasma (atmospheric pressure DBD plasma) as a non-thermal sterilization technology for microorganisms in dried red pepper. The effects of key parameters such as power, exposure time and distance on the sterilization efficiency and the quality of red dried pepper by the atmospheric pressure DBD plasma treatment were investigated. The results revealed that the plasma treatment was very effective for sterilization of Staphylococcus aureus, with 15 min of treatment at 1.0 kW and 20 mm sterilizing 82.6% of the S. aureus. Increasing the power or exposure time and decreasing the exposure distance led to improved sterilization efficiency. The atmospheric pressure DBD plasma treatment showed no effect on the ASTA (American spice trade association) value or hardness of dried red pepper. Furthermore, no effects of atmospheric pressure DBD plasma treatment were observed on the sensory properties of dried red pepper. To assess the storage stability, the dried red pepper was treated with atmospheric pressure DBD plasma (1.5 kW power, 15 min exposure time and 10 mm exposure distance), then stored for 12 weeks at $25^{\circ}C$. Consequently, the ASTA value, hardness and capsaicin concentration of dried red pepper were maintained.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.7
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• pp.45-51
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• 2013

This study is to discuss simulation results with 51 principal chemical reactions in non-thermal plasma space under atmospheric pressure, and the ambient gas was mainly composed of oxygen and nitrogen molecules. The initial density of O and OH radicals under the ambient temperature of 300K is largely generated in comparison with other higher temperature, and the density of O radical decreased from $20{\mu}s$ according to increase the temperature. The initial density of OH radical seemed to decrease steeply at the initial stage. By increasing the initial density of $H_2O$ molecules, O radical's effect was few and the density of OH radical was largely generated about 2 times. In addition, ozone density was increased as increasing the density of O radical, but it was decreased as increasing the density of $H_2O$. In case of the temperature more than 300K, $NO_2$ tend to be removed, but NO was increased than the initial density.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.250.2-250.2
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• 2014

Currently, teeth whitening method which is applicable to dental surgery is that physician expertises give medical treatment to teeth directly dealed with a high concentration of hydrogen peroxide and carbamide peroxide. If hydrogen peroxide concentration is too high for treatment of maximized teeth whitening effect [1], it is harmful to the human body [2]. To the maximum effective and no harmful teeth whitening effect in a short period of time at home, we have observed the whitening effect using carbamide peroxide (15%) and a low-temperature atmospheric pressure plasma jet which is regulated by the Food and Drug Administration. The gas supplied conditions of the non-thermal atmospheric pressure plasma jet was with the humidified (0.6%) gas in nitrogen or air at gas flow rate of 1000 sccm. Also, the measurement of chemical species from the jet was carried out using the optical emission spectroscopy (OES), the evidence of increased reactive oxygen species compared to non-humidified plasma jet. We have found that the whitening effect of the plasma is very excellent through this experiment, when bovine teeth are treated in carbamide peroxide (15%) and water vapor (0.2 to 1%). The brightness of whitening teeth was increased up to 2 times longer in the CIE chromaticity coordinates. The colorimetric spectrometer (CM-3500d) can measure color degree of whitening effect.

• Journal of Korean society of Dental Hygiene
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• v.14 no.5
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• pp.783-788
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• 2014

Objectives : The purpose of this study was to investigate the effect of non-thermal atmospheric pressure plasma jet(NTAPPJ) on surface properties and Streptococcus mutans disinfection of denture base resin. Methods : Self-cured denture base resin (Jet denture repair resin, Lang dental Mfg, co., USA) was used to make specimen($12mm{\times}2mm$). To observe surface change before and after plasma process, surface roughness and contact angle were measured. For sterilization experiments, the surfaces of specimens were treated with nitrogen and air NTAPPJ for 1 minute after S. mutans was inoculated on the material surfaces. Results : Before plasma process, surface roughness of denture base resin was $0.21{\mu}m{\pm}0.02{\mu}m$. After air and nitrogen NTAPPJ process, surface roughness was $0.19{\mu}m{\pm}0.03{\mu}m$ and $0.18{\mu}m{\pm}0.01{\mu}m$ respectively. There was no significant difference(p>0.05). Contact angle of control group without plasma process was $83.81^{\circ}{\pm}3.14^{\circ}$, while after plasma treatment, contact angles of air NTAPPJ and nitrogen NTAPPJ groups were $63.29^{\circ}{\pm}2.27^{\circ}$ and $46.68^{\circ}{\pm}5.82^{\circ}$ respectively. The result showed a significant decrease in contact angle after plasma process(p<0.05). Compared to the control group 6020.33(CFU/mL) without plasma process, CFU decreased significantly after air NTAPPJ 90.75(CFU/mL) and nitrogen NTAPPJ 80.25(CFU/mL) treatment(p<0.05). Conclusions : It was considered that NTAPPJ can be used for denture disinfection without changing surface properties of materials.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.211.1-211.1
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• 2016

Several reports have demonstrated the wide range of nonthermal plasma applications in biomedical field including cancers, diabetics, wound healing and cosmetics. Recently, it has been shown that plasma is able to modulate the p38 MAPK and JUN level in cells which has a crucial role in melanin synthesis and skin pigmentation. Therefore we investigated the effect of plasma on melanogenesis in-vitro using melanoma (B16F10) cells and in-vivo using mouse and zebra fish. To investigate the mechanism of plasma action, plasma device characteristics were measured, reactive species inside and outside the cells were detected, and western blot was performed to find the signaling pathway involved in melanin activation in-vitro and in-vivo. This is the first report presenting the role of nonthermal plasma for melanogenesis which provides a new perspective of plasma in the field of dermatology.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.6
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• pp.577-585
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• 2014

A series of experiments using atmospheric-pressure non-thermal plasma coupled with transition metal catalysts were performed to remove ethylene from agricultural storage facilities. The non-thermal plasma was created by dielectric barrier discharge, which was in direct contact with the catalyst pellets. The transition metals such as Ag and $V_2O_5$ were supported on ${\gamma}-Al_2O_3$. The effect of catalyst type, specific input energy (SIE) and oxygen content on the removal of ethylene was examined to understand the behavior of the hybrid plasma-catalytic reactor system. With the other parameters kept constant, the plasma-catalytic activity for the removal of ethylene was in order of $V_2O_5/{\gamma}-Al_2O_3$ > $Ag/{\gamma}-Al_2O_3$ > ${\gamma}-Al_2O_3$ from high to low. Interestingly, the rate of plasma-catalytic ozone generation was in order of $V_2O_5/{\gamma}-Al_2O_3$ > ${\gamma}-Al_2O_3$ > $Ag/{\gamma}-Al_2O_3$, implying that the catalyst activation mechanisms by plasma are different for different catalysts. The results obtained by varying the oxygen content indicated that nitrogen-derived reactive species dominated the removal of ethylene under oxygen-lean condition, while ozone and oxygen atoms were mainly involved in the removal under oxygen-rich condition. When the plasma was coupled with $V_2O_5/{\gamma}-Al_2O_3$, nearly complete removal of ethylene was achieved at oxygen contents higher than 5% by volume (inlet ethylene: 250 ppm; gas flow rate: $1.0Lmin^{-1}$; SIE: ${\sim}355JL^{-1}$).

• The Journal of the Korean dental association
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• v.54 no.12
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• pp.985-995
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• 2016

Titanium (Ti) has been widely used for dental implant due to great biocompatibility and bonding ability against natural alveolar bone. A lot of titanium surface modification has been introduced in dentistry and, among them, methods to introduce micro/nano-roughened surface were considered as clinically approved strategy for accelerating osseointegration of Ti dental implant. To have synergetic effect with topography oriented favors in cell attachment, chair-side surface treatment with reproducibility of micro/nano-topography is introduced as next strategy to further enhance cellular functionalities. Extensive research has been investigated to study the potential of micro/nano-topography preserved chair-side surface treatment for Ti dental implant. This review will discuss ultraviolet, low level of laser therapy and non-thermal atmospheric pressure plasma on Ti dental implant with micro/nano-topography as next generation of surface treatment due to its abilities to induce super-hydrophilicity or biofunctionality without change of topographical cues.