• Journal of Korean Society of Environmental Engineers
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• v.33 no.9
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• pp.662-669
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• 2011

This study was conducted to biologically convert methane into methanol. Methane contained in biogas was bio-catalytically oxidized by methane monooxygenase (MMO) of methanotrophs, while methanol conversion was observed by inhibiting methanol dehydrogenase (MDH) using MDH activity inhibitors such as phosphate, NaCl, $NH_4Cl$, and EDTA. The degree of methane oxidation by methanotrophs was the most highly accomplished as 0.56 mmol for the condition at $35^{\circ}C$ and pH 7 under 0.4 (v/v%) of biogas ($CH_4$ 50%, $CO_2$ 50%) / Air ratio. By the inhibition of 40 mM of phosphate, 50 mM of NaCl, 40 mM of $NH_4Cl$ and $150{\mu}m$ of EDTA, methane oxidation rate could achieve more than 80% regardless of type of inhibitors. In the meantime, addition of 40 mM of phosphate, 100 mM of NaCl, 40 mM of $NH_4Cl$ and $50{\mu}m$ of EDTA each led to generating the highest amount of methanol, i.e, 0.71, 0.60, 0.66, and 0.66 mmol when 1.3, 0.67, 0.74, and 1.3 mmol of methane was each concurrently consumed. At that time, methanol conversion rate was 54.7, 89.9, 89.6, and 47.8% respectively, and maximum methanol production rate was $7.4{\mu}mol/mg{\cdot}h$. From this, it was decided that the methanol production could be maximized as 89.9% when MDH activity was specifically inhibited into the typical level of 35% for the inhibitor of concern.

• Restorative Dentistry and Endodontics
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• v.33 no.2
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• pp.98-106
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• 2008

The purpose of this study was to evaluate whether intracanal irrigation method could affect the adhesion between intracanal dentin and root canal filling materials (Gutta-percha/AH 26 sealer and Resilon/Epiphany sealer). Thirty extracted human incisor teeth were prepared. Canals were irrigated with three different irrigation methods as a final rinse and obturated with two different canal filling materials (G groups: Gutta-percha/AH 26 sealer, R groups: Resilon/Epiphany sealer) respectively. Group G1, R1-irrigated with 5.25% NaOCl Group G2, R2-irrigated with 5.25% NaOCl, sterile saline Group G3, R3-irrigated with 5.25% NaOCl, 17% EDTA, sterile saline Thirty obturated roots were horizontally sliced and push-out bond strength test was performed in the universal testing machine. After test, the failure patterns of the specimens were observed using Image-analyzing microscope. The results were as follows. 1. Gutta-percha/AH 26 sealer groups had significantly higher push-out bond strength compared with the Resilon/Epiphany sealer groups (p < 0.05). 2. Push-out bond strength was higher when using 17% EDTA followed by sterile saline than using NaOCl as a final irrigation solution in the Resilon/Epiphany sealer groups (p < 0.05). 3. In the failure pattern analysis, there was no cohesive failure in Group G1, G2, and R1. Gutta-percha/AH 26 sealer groups appeared to exhibit predominantly adhesive and mixed failure patterns, whereas Resilon/Epiphany sealer groups exhibited mixed failures with the cohesive failure occurred within the Resilon substrate.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1900-1902
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• 2004

The degradation systems of non degradable waste water consist of the arc plasma torch, power supply, a feeder of liquid waste and reactors. Output of stable plasma torch, suitable air flux, microscopic atomizing state of waste water and long reaction section must be to degrade waste water more efficiently. In this paper, we are designed the stable power system, the microscopic atomizing state of waste water and the efficient reactors to satisfy various conditions. Non degradable wast water used in this work was $Na_2$EDTA of 1.0 mol. The concentration of $CO_2$ and EDTA was analyzed using GC (Gas Chromatography) and HPLC (High Performance Liquid Chromatography). In the result show that $CO_2$ concentration was about 96% and EDTA was degraded approximately 96%.

• Restorative Dentistry and Endodontics
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• v.28 no.1
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• pp.89-99
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• 2003

The purpose of this study was to investigate the bonding of resin- based root canal sealer, AH26 when the sealer was applied as a thin layer between dentine and gutta-percha surface. In this study forty non-caries extracted human molars and resin-based root canal sealer(AH 26, DeTrey/Dentsply, Germany) were used. Disks of gutta-percha, 6mm in diameter.6mm thick (Diadent/Dentsply, Korea) for thermoplastic obturation were used and dentin surfaces were treated with 2% NaOCl(Group 1) or 2%NaOCl+17% EDTA(Group 3). Disks of gutta-Percha, 6mm in diameter.6mm thick (Diadent/Dentsply, Korea) for conventional obturation were used and dentin surface were treated with 2% NaOCl(Group 2) or 2%NaOCl+17% EDTA(Group 4). Enamel was removed by a horizontal section 1mm below the deepest portion of the central occlusal groove by using a watercooled low speed diamond saw. A second horizontal section was done around cementoenamel junction. Exposed dentin surface was cut to approximately $8{\times}8{\;}mm$ rectangular shape and was ground against 320, 400, 600 grade silicon carbide abrasive paper serially. After grinding, the dentine surface were soaked in a solution of 2% NaOCl for 30 minutes and twenty of specimens were treated with 17% EDTA solution for 1 minute. The treated specimens were washed and dried, Root canal sealer, AH26 was prepared according to the manufacture's instructions The Gutta-percha and dentin surface were coated with a thin layer of the freshly mixed seal or. The specimens were left overnight at room temperature. After their initial set, they were transferred to an incubator at $37$^{\circ}C$ for 72 h. After 72 hours, resin blocks were made. The resin block was serially sectioned vertically into stick of $1{\cdot}1mm$. Twenty sticks were prepared from each group. After that, tensile bond strength f3r each stick was measured with Microtensile Tester Failure patterns of the specimens at the interface between gutta-percha and dentin were observed under the SEM(x1000) and Stereomicroscope (LEICA M42O, Meyer Inst., TX U.S.A) at 1.25 x25 magnification. The results were statistically analysed by using a One-way ANOVA and Tukey's test. The results were as follows; 1. Tensile bond strengths($mean{\pm}SD$) were expressed with ascending order as follows: Group 1, $3.09{\pm}$ 1.05Mpa : Group 2, $6.23{\pm}1.16MPa$ : Group 3, $7.12{\pm}1.07MPa$ : Group 4, $10.32{\pm}2.06MPa$. 2. Tensile bond strengths of the group 2 and 4 used disks of gutta-percha for conventional obturation were significantly higher than that of the group 1 and 3 used fir thermoplastic obturation. (p < 0.05). 3. Tensile bond strengths of the group 3 and 4 treated with 2% NaOC1+17% EDTA were significantly higher than that of the group 1 and 2 treated with 2% NaOCl. (p < 0.05). 4. In analysis of failure patterns at the interface between sealer and gutta-percha, there were observed 49 (61%)cases of adhesive failure patterns and 31 (39%) cases of mixed failures patterns.

• Restorative Dentistry and Endodontics
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• v.45 no.2
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• pp.23.1-23.12
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• 2020

Objectives: This study aimed to summarize the outcome of in vitro studies comparing the antibacterial effectiveness of QMix with other irrigants against Enterococcus faecalis. Materials and Methods: The research question was developed by using population, intervention, comparison, outcome, and study design framework. The literature search was performed using 3 electronic databases: PubMed, Scopus, and EBSCOhost until October 2019. The additional hand search was performed from the reference list of the eligible studies. The risk of bias of the studies was independently appraised using the revised Cochrane Risk of Bias tool (RoB 2.0). Results: Fourteen studies were included in this systematic review. The overall risk of bias for the selected studies was moderate. QMix was found to have a higher antimicrobial activity compared to 2% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA), 2% chlorhexidine (CHX), mixture of tetracycline isonomer, an acid and a detergent (MTAD), 0.2% Cetrimide, SilverSol/H2O2, HYBENX, and grape seed extract (GSE). QMix had higher antibacterial efficacy compared to NaOCl, only when used for a longer time (10 minutes) and with higher volume (above 3 mL). Conclusions: QMix has higher antibacterial activity than 17% EDTA, 2% CHX, MTAD, 0.2% Cetrimide, SilverSol/H2O2, HYBENX, GSE and NaOCl with lower concentration. To improve the effectiveness, QMix is to use for a longer time and at a higher volume.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.2
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• pp.240-245
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• 1993

The optimum pH and temperature for the purified extracellular enzyme activity were 8.0 and 37$^{\circ}C$, respectively. NaCl was required for the activation of the enzyme and optimum concentration was 0.5M. This enzyme activity was inhibited by HgC $l_2$, CoC $l_2$ and ZnC $l_2$ and stimulated by CaC $l_2$. The activity of enzyme was increased by L-cysteine and 2-mercaptoethanol, but decreased by ο-phenanthroline, $\rho$-CMB, EDTA and iodoacetate. The $K_{m}$ and $V_{max}$ values of extracellular enzyme appeared as 0.717% and 15.39U/mg, respectively.y.

• Restorative Dentistry and Endodontics
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• v.26 no.4
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• pp.350-359
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• 2001

목적 - 근관형성시 근관내 상아질벽에는 항상 도말층(smear layer)이 형성되는데, 이는 상아질, 치수조직 잔사, 조상아세포 돌기, 때로는 미생물 등으로 구성되며, 주사전자현미경상으로는 비규칙적이며, 무정형의 구상(granular)구조물로 관찰된다. 본 연구에서는 도말층의 유무에 따른 혐기성 미생물, Prevotella nigrescens의 근관내 상아질 부착정도를 주사전자현미경으로 평가하고자 한다. 지금까지 사용되었던 실험방법에 비하여 보다 임상적 환경에 가까운 실험방법을 고안, 신빙성 있는 연구결과를 기대할 수 있도록 하였다. 방법 - 치주질환이나 외상 등의 원인으로 발거된 상, 하악 전치 18개를 사용하였다. 각 치아의 치관부를 백악법랑경계부위에서 절단하고, 1군(5개치아)은 10ml의 생리식 염수를, 2군(5개치아)과 3군(5개치아)은 10ml의 3.5% NaOCl을 근관관주용액으로 사용하여 근관형성을 하였다. 근관형성 완료후 1군과 2군은 10ml의 생리식염수로, 3군은 10ml의 0.5M EDTA용액으로 final flush를 시행하여, 3군의 도말층을 제거하였다. 치근수직절단과 ethylene oxide(EO) gas 소독후 1, 2, 3군의 시편(각군10개시편)을 Prevotella nigrescens가 부유된 Brain Heart Infusion with Yeast estract, Hemin and Menadione(BHIYHM) broth내에 37$^{\circ}C$에서 3시간 동안 incubation했다. 4, 5, 6군은 실험과정을 검증하기 위한 대조군으로써, 4군(1개치아)과 5군(1개치아)은 1군, 2군과 같이 각각 생리식염수와 NaOCl만을 이용한 근관형성으로 도말층을 잔존시키고, 6군(1개치아)은 3군과 같이 NaOCl과 EDTA를 적용하여 도말층을 제거한 후, 치근 수직절단과 EO gas 소독을 시행했다. 모든 시편(1, 2, 3, 4, 5, 6군)을 통상의 방법에 따라 처리한 후 주사전자현미경을 통하여 관찰, 근관내면에 부착되어 있는 Prevotella nigrescens의 개수, 모양, 상아세관 및 도말층과의 관계 등을 관찰, 비교, 분석하였다. 결과는 t-test와 one-way ANOVA를 통하여 통계처리 하였다. 결론 - 1. 근관형성 후 근관내 상아질 표면 전체는 도말층으로 덮여 있는 양상을 보였다. 2. 3.5% NaOCl과 0.5M EDTA를 적용하여 근관내 도말층을 효과적으로 제거할 수 있었으며, 상아세관 개구부가 확연히 노출되어 있는 소견을 관찰할 수 있었다. 3. 도말층이 덮인군에서 미생물의 부착이 유의성 있게 높았다(P<0.05). 4. 근관 형성중 형성되어 근관 상아질을 덮고 있는 도말층이 미생물의 부착을 증가시켜, 근관 재감염의 기회를 증가시킴을 알 수 있었다.

• Restorative Dentistry and Endodontics
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• v.40 no.3
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• pp.216-222
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• 2015

Objectives: To evaluate the effects of copolymer of acrylic acid and maleic acid (Poly[AA-co-MA]) and calcium hypochlorite ($Ca(OCl)_2$) on root canal dentin using scanning electron microscope (SEM). Materials and Methods: Twenty-four single-rooted teeth were instrumented and the apical and coronal thirds of each root were removed, leaving the 5 mm middle thirds, which were then separated into two pieces longitudinally. The specimens were randomly divided into six groups and subjected to each irrigant for 5 min as follows: G1, $Ca(OCl)_2$; G2, Poly(AA-co-MA); G3, $Ca(OCl)_2$ + Poly(AA-co-MA); G4, sodium hypochlorite (NaOCl); G5, ethylenediaminetetraacetic acid (EDTA); G6, NaOCl+EDTA. The specimens were prepared for SEM evaluation. Smear layer, debris and erosion scores were recorded by two blinded examiners. One image from G3 was analyzed with energy dispersive spectroscopy (EDS) on suspicion of precipitate formation. Data were analyzed using the Kruskal-Wallis and Dunn tests. Results: G1 and G4 showed the presence of debris and smear layer and they were statistically different from G2, G3, G5 and G6 where debris and smear layer were totally removed (p < 0.05). In G1 and G4, erosion evaluation could not be done because of debris and smear layer. G2, G3 and G5 showed no erosion, and there was no significant difference between them. G6 showed severe erosion and was statistically different from G2, G3 and G5 (p < 0.05). EDS microanalysis showed the presence of Na, P, and Ca elements on the surface. Conclusions: Poly(AA-co-MA) is effective in removing the smear layer and debris without causing erosion either alone or with $Ca(OCl)_2$.

• Applied Biological Chemistry
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• v.14 no.3
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• pp.177-182
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• 1971

A new method for the measure of iron pools using 0.02M EDTA and $Na_2S_2O_4$ was tested on Akagare diseased and healthy rice leaf tissue 1) The proposed method could fraction iron into four fractions; ferrous iron($Fe^{++}$), ferric iron($Fe^{+++}$) precipitated iron(PFe) and bound iron(BFe) well indicating the physiological status of tissue. 2) The pattern of iron pools appears to be $Fe^{+++}>PFe>BFe>Fe^{++}$ in most physiologically favorable status of iron, $PFe>Fe^{+++}>BFe>Fe^{++}$ in favorable status, $BFe>Fe^{+++}>PFe>Fe^{++}$ in unfavorable status and $BFe>PFe>Fe^{+++}>Fe^{++}$ in toxic status. 3) The percentage of each fraction to total iron was less than 10 for $Fe^{++}$, 20 to 40 for $Fe^{+++}$ and PFe and 20 to 50 for BFe. 4) Ferrous iron was always higher in upper half leaf, the appearance of which is less healthier than lower half indicating that there is more active metabolic system in which ferrous iron is involved.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.6
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• pp.497-508
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• 2017

This study aimed to investigate correlations between concentrations of extractable Arsenic (As) with varying chemical solutions (0.1 M $Ca(NO_3)_2$, 0.1 M $(NH_4)2HPO_4$, 0.5 M EDTA, Mehlich 3, and 0.5 M $NaHCO_3$) and those of As in crops, and then to seek the most suitable soil extraction method for predicting the potential of As uptake in crops cultivated in soils contaminated with As. For a mesocosm experiment, pepper (Capsicum annuum L.), soybean (Glycine max L.), and rice (Oryza sativa L.) were cultivated for three months in pots containing soils taken from the arable areas near abandoned mines in Korea. Following the cultivation, soil pH and DOC significantly increased by treatments of lime and lime plus compost, respectively, while insignificant influences in changing total and all extractable As concentrations were found in all soils. Arsenic concentration in edible part of all crops considerably depended on the extractable As concentration in the soils, particularly with Mehlich 3. All extractable As concentrations in the soils of C. annuum and G. max were significantly correlated with As concentration in their edible parts. For O. sativa, the extractable concentrations of Mehlich 3 ($R^2$: 0.18 at p: 0.006) and EDTA ($R^2$: 0.11 at p: 0.036) showed only marked relationships with As concentration in the edible part. These results may indicate that the Mehlich 3 and EDTA are soil extractants to determine phytoavailable As in soil that provide better prediction for As transfer from soil to crop.