• The Journal of Korean Academy of Prosthodontics
• /
• v.58 no.1
• /
• pp.14-22
• /
• 2020

Purpose: The aim of this study is to evaluate the effectiveness of MnO₂-diatom microbubbler (DM) on the surface of prosthetic materials as a mouthwash by comparing the biofilm removal effect with those previously used as a mouthwash in dental clinic. Materials and methods: DM was fabricated by doping manganese dioxide nanosheets to the diatom cylinder surface. Scanning electron microscopy (SEM) was used to observe the morphology of DM and to analyze the composition of doped MnO₂. Stereomicroscope was used to observe the reaction of DM in 3% hydrogen peroxide. Non-precious metal alloys, zirconia and resin specimens were prepared to evaluate the effect of biofilm removal on the surface of prosthetic materials. And then Streptococcus mutans and Porphyromonas gingivalis biofilms were formed on the specimens. When 3% hydrogen peroxide solution and DM were treated on the biofilms, the decontamination effect was compared with chlorhexidine gluconate and 3% hydrogen peroxide solution by crystal violet staining. Results: Manganese dioxide was found on the surface of the diatom cylinder, and it was found to produce bubble of oxygen gas when added to 3% hydrogen peroxide. For all materials used in the experiments, biofilms of the DM-treated groups got effectively removed compared to the groups used with chlorhexidine gluconate or 3% hydrogen peroxide alone. Conclusion: MnO₂-diatom microbubbler can remove bacterial membranes on the surface of prosthetic materials more effectively than conventional mouthwashes.

• Journal of Soil and Groundwater Environment
• /
• v.10 no.2
• /
• pp.35-43
• /
• 2005

Bioslurping combines the three remedial approaches of bioventing, vacuum-enhanced free-product recovery, and soil vapor extraction. Bioslurping is less effective in tight (low-permeability) soils. The greatest limitation to air permeability is excessive soil moisture. Optimum soil moisture is very soil-specific. Too much moisture can reduce air permeability of the soil and decrease its oxygen transfer capability. Too little moisture will inhibit microbial activity. So Modified Fenton reaction as chemical treatment which can overcome the weakness of Bioslurping was experimented for simultaneous treatment. Although the diesel removal efficiency of SVE process increased in proportion to applied vacuum pressure, SVE process was difficulty to remediation quickly semi- or non-volatile compounds absorbed soil strongly. And SVE process had variation of efficiency with distance from the extraction well and depth a air flow form of hemisphere centering around the well. Below 0.1 % hydrogen peroxide shows the potential of using hydrogen peroxide as oxygen source but the co-oxidation of chemical and biological treatment was impossible because of the low efficiency of Modified Fenton reaction at 0.1 % (wt) hydrogen peroxide. NTA was more efficiency than EDTA as chelating agent and diesel removal efficiency of Modified Fenton reaction increased in proportion to hydrogen peroxide concentration. Hexadecane as typical aliphatic compound was removed less than Toluene as aromatic compound because of its structural stability in Modified Fenton reaction. What minimum 10% hydrogen peroxide concentration has good remediation efficiency of diesel contaminated groundwater may show the potential use of Modified Fenton reaction after bioslurping treatment.

• Journal of the Korean Society of Food Culture
• /
• v.20 no.1
• /
• pp.103-112
• /
• 2005

The objective of this study was to clarify the effect of addition of green tea powder(0%, 2%, 4%, 6%, 8%) to Yackwa on quality and preservation. Addition of 4% green tea powder turned out to give positive effect on expansion. In test of physical characters, addition of green tea powder had a tendency to lower hardness, cohesiveness, springness and gumminess but to enhance brittleness. Considering the rancidity of oil within Yackwa, addition of green tea powder tended to show lower acid value and peroxide value than non-added treatment but its difference was slight. At the sensory test, surface color, bitterness and green tea flavor were strong but sweet and savory taste weak when green team powder was added(p<0.05). Overall quality appeared to have improved to 5.55 points which is compared to non-addition when the powder was added 4%(p<0.05). In conclusion, 4% addition of green tea powder would be the usefull method to enhance preference and quality of Yackwa.

• Carbon letters
• /
• v.20
• /
• pp.19-25
• /
• 2016

Activated carbon fiber (ACF) surfaces are modified using an electron beam under different aqueous solutions to improve the NO gas sensitivity of a gas sensor based on ACFs. The oxygen functional group on the ACF surface is changed, resulting in an increase of the number of non-carbonyl (-C-O-C-) groups from 32.5% for pristine ACFs to 39.53% and 41.75% for ACFs treated with hydrogen peroxide and potassium hydroxide solutions, respectively. We discover that the NO gas sensitivity of the gas sensor fabricated using the modified ACFs as an electrode material is increased, although the specific surface area of the ACFs is decreased because of the recovery of their crystal structure. This is attributed to the static electric interaction between NO gas and the non-carbonyl groups introduced onto the ACF surfaces.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.12S
• /
• pp.1181-1186
• /
• 2003

Chemical Mechanical Polishing (CMP) is an essential dielectric planarization in multilayer microelectronic device fabrication. In the CMP process, it is necessary to minimize the extent of surface defect formation while maintaining good planarity and optimal material removal rates. The polishing mechanism of W-CMP process has been reported as the repeated process of passive layer formation by oxidizer and abrasion action by slurry abrasives. Thus, it is important to understand the effect of oxidizer on W passivation layer, in order to obtain higher removal rate (RR) and very low non-uniformity (NU %) during W-CMP process. In this paper, we compared the effects of oxidizer or W-CMP process with three different kind of oxidizers with 5 wt% hydrogen peroxide such as Fe(NO$_3$)$_3$, H$_2$O$_2$, and KIO$_3$. The difference in removal rate and roughness of W in stable and unstable slurries are believed to caused by modification in the mechanical behavior of Al$_2$O$_3$ particles in presence of surfactant stabilizing the slurry.

• Journal of Community Nutrition
• /
• v.1 no.2
• /
• pp.88-97
• /
• 1999

The purpose of this study was to investigate the nutritional status of serum minerals, ceruloplasmin, and ferroxidase activity in female adolescent students according to their smoking status. The subjects were 87 non-smokers and 88 smokers, who were female high school students. The smokers were divided into tow groups by smoking status, 35 light smokers(pack-year<1) and 53 smokers(pack-year$\geq$1). The serum concentrations of 6 minerals were determined by ICP emission spectroanalyzer. The serum concentration of ceruloplasmin and ceruloplasmin ferroxidase activity were determined. All data were statistically analyzed by SAS PC package program. The serum minerals concentrations of all subjects were in a normal range. There were significantly differences in the concentrations of serum copper, zinc, magnesium, and phosphorus by smoking status while there were no significant differences in the concentrations of serum iron and manganese by smoking status. Furthermore there were no significant differences in the ceruloplasmin concentration and ferroxidase activity by smoking status. In conclusion, smoking status altered the serum levels of some minerals in healthy young women. The minerals levels in light smokers with relatively short pack-year(pack-year<1) were altered compared to those in non-smokers or smokers. This finding seemed to be consistent with the results of previously published data related to antioxidant vitamin and lipid peroxide levels. However further research is needed to clarify these findings in female adolescent smokers.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.26 no.2
• /
• pp.20-27
• /
• 2022

Hypergolic propellant ignited spontaneously when fuel and oxidizer contact without ignition system. Due to this characteristic, the risk of accidents is high when new propellants are evaluated. Prevention of accidents is very important because the damage can be large when the accident occur. In this work, we proposed non-ignition evaluation method which can replace conventional ignition evaluation method by using microreactor. The reactor was fabricated by MEMS. The heat of reaction as according to fuel and NaBH₄ was estimated. At the condition of highest heat of reaction ignition was observed by drop test.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.29 no.1
• /
• pp.120-127
• /
• 2000

Deep-fat frying is a common cooking practice. There has been considerable concern regarding the mutagenic and carcinogenic potential of thermally oxidized oils. Studies on deep-fried foods so far have revealed not much on the mutagenicity of the oils in the foods. Therefore, in the present study, it was attempted to investigate the mutagenicity ofthe thermally oxidized safflower oil. Oil was heated in a home-fryer at a temperature of 180$\pm$3$^{\circ}C$ for 48 hours. Oil samples were taken at 0, 8, 16, 24, 32, 40 and 48 hours of heating, respectively. Each sample was used to study the changes in peroxide value (POV), acid value (AV), iodine value (IV), conjugated dienoic acid (CDA) content, %, and fatty acid composition. Another series of samples were fractionated into non-polar and polar fractions by column chromatography. The mutagenicity of the samples taken from the thermally oxidized oils, as well as the non-polar and polar fractions of the thermally oxidized oils, was investigated with the Ames test. The Ames test was carried out with and without metabolic activation. Bacterial tester strains used in the present study were the histidine auxotrophic strains of Salmonella typhimurium TA100, TA1535 and TA102 were used for the detection of base pair mutations, and TA98 and TA1537 for frame shift mutations. Each series of samples was dissolved in tetraphydrofuran (inhibitor-free) and tested at doses ranging from 0.05 to 5 mg/plate. None of the oil samples taken during the 48 hour oxidation period showed any mugagenic activity. This was the case, even after the activaton with 59 mix. Also, none of the polar and non-polar fractions showed any mutagenic activity on all the strains tested.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.9
• /
• pp.1401-1411
• /
• 2019

Mycobacterial cell walls comprise thick and diverse lipids and glycolipids that act as a permeability barrier to antibiotics or other chemical agents. The use of OH radicals from a non-thermal plasma jet (NTPJ) for the inactivation of mycobacteria in aqueous solution was adopted as a novel approach. Addition of water vapor in a nitrogen plasma jet generated OH radicals, which converted to hydrogen peroxide ($H_2O_2$) that inactivated non-pathogenic Mycobacterium smegmatis and pathogenic Mycobacterium tuberculosis H37Rv. A stable plasma plume was obtained from a nitrogen plasma jet with 1.91 W of power, killing Escherichia coli and mycobacteria effectively, whereas addition of catalase decreased the effects of the former. Mycobacteria were more resistant than E. coli to NTPJ treatment. Plasma treatment enhanced intracellular ROS production and upregulation of genes related to ROS stress responses (thiolrelated oxidoreductases, such as SseA and DoxX, and ferric uptake regulator furA). Morphological changes of M. smegmatis and M. tuberculosis H37Rv were observed after 5 min treatment with $N_2+H_2O$ plasma, but not of pre-incubated sample with catalase. This finding indicates that the bactericidal efficacy of NTPJ is related to the toxicity of OH and $H_2O_2$ radicals in cells. Therefore, our study suggests that NTPJ treatment may effectively control pulmonary infections caused by M. tuberculosis and nontuberculous mycobacteria (NTM) such as M. avium or M. abscessus in water.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2021.04a
• /
• pp.60-60
• /
• 2021

Non-alcoholic fatty liver disease (NAFLD), especially including non-alcoholic steatohepatitis (NASH) is one of the common diseases with 25% of prevalence globally, but there is no thera-peutic access available. Amomum villosum var. xanthioides (Wall. ex Baker) T.L.Wu & S.J.Chen (AX), which is a medicinal herb and traditionally used for treating digestive tract disorders in Asia countries. We aimed to examine pharmacological effects of ethyl acetate fraction of AX (AXEF) against ER stress-induced NASH mice model using C57/BL6J male mice by tunicamycin (TM, 2 mg/kg) injection focusing on the oxidative stress. Mice were orally administrated AXEF (12.5, 25, or 50 mg/kg), silymarin (50 mg/kg) or distilled water daily for 5 days, and outcomes for fatty liver, inflammation, and oxidative stress were measured in serum or liver tissue levels. AXEF drastically attenuated hepatic ER stress-induced NASH which were evidenced by decreases of li-pid droplet accumulations, serum liver enzymes, hepatic inflammations, and cell death signals in the hepatic tissue or serum levels. Interestingly, AXEF showed potent antioxidant effects by quenching of reactive oxidative stress and its final product of lipid peroxide in the hepatic tissue, specifically increase of metallothionein (MT). To confirm underlying actions of AXEF, we ob-served that AXEF increase MT1gene promoter activities in the physiological levels. Collectively, AXEF showed antioxidant properties on TM-induced ER stress of NASH by enhancement of MTs.