• Journal of Radiation Protection and Research
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• 제21권2호
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• pp.99-105
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• 1996

림프구와 림프종에 고준위 방사선(8Gy)을 조사했을 때. 저준위 방사선을 먼저 조사한 경우 세포 생존률이 3.7배 증가하는 것이 관찰되었다 세포 생존률은 고준위 방사선 조사로 발생되는 산소 라디칼의 제거. 변성된 유전자와 단백질의 제거, 변화된 세포의 제거 등으로 증가할 수 있다. 본 연구에서는 저준위 방사선 조사로 유도되는 방사선 저항기전을 알아보기 위하여, 고준위 방사선 조사시 발생되는 산소 라디칼을 제거하는 효소들의 활성과 방사선 보호제로 알려진 glutathione의 양을 측정하였다 림프종의 경우 저준위 방사선 조사시 peroxidase의 활성이 133.3%로 증가하였다. 림프구의 경우는 superoxide dismutase, glucose-6-phoshpate dehydrogenase와 glutathione의 활성이 각각 138.5%. 122.4%. 120.8%로 증가하였으며. 이들 효소들의 활성은 저 준위방사선 조사 간격이 7 시간일 때 가장 증가되었다.

• 한국식품영양학회지
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• 제30권6호
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• pp.1286-1291
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• 2017

In this study, Pyracantha angustifolia (Franch.) C. K. Schneid was extracted with 70% methanol at room temperature for 48 hrs and concentrated under reduced pressure to measure its total polyphenol contents; furthermore, the effect of electron donating ability was examined. Methylene chloride, ethyl acetate, and methanol were used to fractionate the extract to testify total polyphenol contents, electron donating abilities, the removal abilities of superoxide radical as well as hydrogen peroxide. The total polyphenol contents were $2007.30{\pm}109.28{\mu}g\;GAE/mL$ in 70% methanol extract, $273.39{\pm}10.19{\mu}g\;GAE/mL$ in methylene chloride fraction, $80.57{\pm}0.64{\mu}g\;GAE/mL$ in ethyl acetate fraction, and $1,160.87{\pm}44.71{\mu}g\;GAE/mL$ in methanol fraction. The total polyphenol contents showed significant differences (p<0.05) between the solvents. The electron donating ability was $79.07{\pm}7.31%$ for 70% methanol extract, $22.34{\pm}0.64%$ for methylene chloride fraction, $5.33{\pm}0.28%$ for ethyl acetate fraction, and $32.26{\pm}1.10%$ for methanol fraction. The electron donating abilities were significantly different(p<0.05) between the solvents. The removal ability of superoxide radical was $0.018{\pm}0.003$ for 70% methanol extract, $0.007{\pm}0.002$ for methylene chloride fraction, $0.0147{\pm}0.003$ for ethyl acetate fraction, and nothing for methanol fraction. The measurement of hydrogen peroxide decomposition was $0.022{\pm}0.0046$ for 70% methanol extract, $0.0027{\pm}0.0015$ for methylene chloride fraction, $0.0037{\pm}0.0012$ for ethyl acetate fraction, and $0.0009{\pm}0.0001$ for methanol fraction.

• 한국환경과학회지
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• 제27권8호
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• pp.621-629
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• 2018

Many chemically active species such as ${\cdot}H$, ${\cdot}OH$, $O_3$, $H_2O_2$, hydrated $e^-$, as well as ultraviolet rays, are produced by Dielectric Barrier Discharge (DBD) plasma in water and are widely use to remove non-biodegradable materials and deactivate microorganisms. As the plasma gas containing chemically active species that is generated from the plasma reaction has a short lifetime and low solubility in water, increasing the dissolution rate of this gas is an important challenge. To this end, the plasma gas and water within reactor were mixed using the air-automizing nozzle, and then, water-gas mixture was injected into water. The dissolving effect of plasma gas was indirectly confirmed by measuring the RNO (N-Dimethyl-4-nitrosoaniline, indicator of the formation of OH radical) solution. The plasma system consisted of an oxygen generator, a high-voltage power supply, a plasma generator and a liquid-gas mixing reactor. Experiments were conducted to examine the effects of location of air-automizing nozzle, flow rate of plasma gas, water circulation rate, and high-voltage on RNO degradation. The experimental results showed that the RNO removal efficiency of the air-automizing nozzle is 29.8% higher than the conventional diffuser. The nozzle position from water surface was not considered to be a major factor in the design and operation of the plasma reactor. The plasma gas flow rate and water circulation rate with the highest RNO removal rate were 3.5 L/min and 1.5 L/min, respectively. The ratio of the plasma gas flow rate to the water circulation rate for obtaining an RNO removal rate of over 95% was 1.67 ~ 4.00.

• Restorative Dentistry and Endodontics
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• 제26권5호
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• pp.399-408
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• 2001

Tooth bleaching has been prevailing recently for its ability to recover the color and shape of natural teeth without reduction of tooth material. However, it has been reported that bleaching procedure adversely affects the adhesive bond strength of composite resin to tooth. At the same time the bond strength was reported to be regained by application of some chemical agents. The purpose of this in vitro study was to investigate the effect of the removal of residual peroxide on the composite- enamel adhesion and also evaluated fracture mode between resin and enamel after bleaching. Sixty extracted human anterior and premolars teeth were divided into 5 groups and bleached by combined technique using of office bleaching with 35 % hydrogen peroxide and matrix bleaching with 10% carbamide peroxide for 4 weeks. After bleaching, the labial surfaces of each tooth were treated with catalase, 70% ethyl alcohol, distilled water and filled with composite resin. Shear bond strength was tested and the fractured surfaces were also examined with SEM. Analysis revealed significantly higher bond strength values. (p＜0.05) for catalase-treated specimens, but water-treated specimens showed reduction of bond strength, alcohol- treated specimens had medium value between the two groups(p＜0.05). The fracture mode was shown that the catalase group and the alcohol group had cohesive failure but the water sprayed group had adhesive failure. It was concluded that the peroxide residues in tooth after bleaching seems to be removed by gradual diffusion and the free radical oxygen from peroxide prevents polymerization by combining catalyst in the resin monomer. Therefore it may be possible to eliminate the adverse effect on the adhesion of composite resin to enamel after bleaching by using water displacement solution or dentin bonding agent including it for effective removal of residual peroxide.

• 상하수도학회지
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• 제21권4호
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• pp.375-383
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• 2007

Treatment efficiency research was performed using Fenton process and the electrochemical process in the presence of ferrous ion and hydrogen peroxide for the industrial wastewater including 1,4-Dioxane produced during polymerization of polyester. The Fenton process and the electrochemical Iron Redox Reaction (IRR) process were applied for this research to use hydroxyl radical as the powerful oxidant which is continuously produced during the redox reaction with iron ion and hydrogen peroxide. The results of $COD_{Cr}$ and the concentration of 1,4-Dioxane were compared with time interval during the both processes. The rapid removal efficiency was obtained for Fenton process whereas the slow removal efficiency was occurred for the electrochemical IRR process. The removal efficiency of $COD_{Cr}$ for 310 minutes was 84% in the electrochemical IRR process with 1,000 mg/L of iron ion concentration, whereas it was 91% with 2,000 mg/L of iron ion concentration. The lap time to remove all of 1,4-Dioxane, 330 mg/L in the wastewater took 150 minutes with 1,000 mg/L of iron ion concentration, however it took 120 minutes with 2,000 mg/L of iron ion concentration in the electrochemical IRR process.

• 대한안전경영과학회지
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• 제15권3호
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• pp.127-132
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• 2013

This study shows an air-purification test by the UV lamp on which TiO2 catalyst is deposited with glass fiber in the reactor chamber. This test was based on the fundamental data of air-purifier as assessing a removing ability on various contaminants such as CH3COOH, NH3, NO and SO2 as variation of the TiO2 coating, the wave of UV lamp, and the additive CaO. As a result, the highest decomposing removal ratio was shown when 5-times coated glass fiber was used. It can be due to the recombination reaction of electrons and electron-hole in the loaded CaO. Thus, the decomposing removal ratio increased as the recombination ratio decreased. In addition, it was confirmed that the decomposing removal ratio lowered when CaO was considerably deposited because it hided the lamp of OH-1 radical.

• 한국의류학회지
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• 제23권7호
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• pp.1064-1072
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• 1999

Nylon fabric was grafted for the purpose of the development of detergency against the hemoglobin as a protein soil. By free-radical producing chemical initiator systems the graft using acrylic acid(AA) as a hydrophilic vinyl monomer was performed to change surface energies in the presence of ammonium persulfate(APS) as an initiator and then acrylic acid grafted Nylon was treated with NaOH solution. The surface morphology for Nylon-g-NaAA with changing graft rate were studied by scanning electron microscopy (SEM) The properties of the Nylon such as diameter tenacity elongation contact angle and the hemoglobin removal were also investigated. The diameter of grafted Nylon fiber increased as the graft ratio increased. The tenacity of grafted Nylon also increased with increasing graft ratio up to 15% The elongation however decreased gradually according to graft, The contact angle decreased after graft and alkaline treatment. The amount of hemoglobin on the grafted Nylon increased in proportion to the graft ratio. Hemoglobin was easily removed from grafted Nylon while it was difficult to be removed from ungrafted Nylon. The detergency of hemoglobin for grafted Nylon decreased when the graft ratio exceeded 15% The removal of hemoglobin increased markedly with increasing hemoglobin content and revolution speed. Therefore the removal of hemoglobin was improved due to graft and alkaline treatment.

• 대한환경공학회지
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• 제28권2호
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• pp.137-143
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• 2006

본 연구는 오존 단독, UV 단독 및 오존/UV 혼합 공정을 이용하여 DEP의 제거 특성을 알아보고자 수행되었다. 실험 결과로서, 오존/UV 공정에서 가장 높은 제거 효율을 나타냈다. 오존 및 오존/UV 공정에서 DEP의 분해 경로를 파악하기 위해서 pH 변화 및 OH 라디칼($OH^{\circ}$) scavenger 첨가 유무에 따른 제거 정도를 비교하였다. 그 결과, DEP 분해 시 $OH^{\circ}$과의 반응이 주된 반응이며, 오존에 의한 직접 산화 반응 및 UV에 의한 광분해 반응은 무시할 정도로 작았다. 오존 및 오존/UV 공정에서 DEP의 의사일차속도상수를 비교하였을 때, 오존/UV 공정은 일차속도에 잘 일치한 반면 오존 단독 공정에서는 일차속도로 제거되는 경향이 초기에 빠르고 일정한 반응시간 이후에 느려지는 두 영역으로 나뉘어 나타났다. 오존 및 오존/UV 긍정에 의해 생성되는 DEP 산화 부산물을 간접적으로 확인하기 위해 HPLC 스펙트럼을 조사한 결과 미지의 물질이 검출되었으며, 반응시간에 따라 이 물질이 생성되다가 감소하는 일정한 경향을 보였다. 또한, 오존/UV 혼합공정에서 높은 TOC 제거율을 나타내 DEP 및 DEP 산화부산물까지 완전 산화됨을 확인하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제11권6호
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• pp.76-82
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• 2006

일반적으로 Fenton 반응 공정을 실제 오염토양에 적용하기에는 다소 무리가 있다. 그 이유로 대표적인 Fenton 반응공정인 고전적인 Fenton 반응은 낮은 pH에서 우수한 처리효율을 보이고 있기 때문이다. 또한, 철이온의 투입을 대신하여 철광석을 이용하는 Fenton-like 반응도 철광석 표면에서 hydroxyl radical을 생성하나 높은 pH에서는 다량의 수산화물과의 경쟁반응으로 인하여 그 활성이 상당히 감소되어진다. 이러한 단점을 보완하기 위하여 중성영역의 pH에서 철이온-chelating agent의 복합체를 촉매로 사용하는 modified Fenton 반응이 제시 되어지고 있다. 이 처리방식의 경우에는 다량의 철이온의 투입이 요구되어진다. 따라서, 본 실험에서는 Fenton-like 반응과 modified Fenton 반응의 효율적인 접목으로 중성영역에서의 chelating agent의 투입으로 철광석으로부터 철이온을 용출하여 복합체를 형성함으로 혼합 Fenton 공정에서 부가적인 촉매로 사용되어짐으로 오염물 처리효율을 크게 향상시킨 기법 개발을 진행하였다. 2,4,6-Trinitrotoluene은 본 실험에서 오염원으로 사용하였으며, chelating agent에 의해 용출된 철이온이 약 0.1 mM 이상일 경우 Fenton-like 반응에 비하여 상당히 좋은 제거효율을 보였다. 혼합 Fenton 공정의 최대제거효율은 magnetite-NTA 시스템으로써 약 76%의 제거효율과 magnetite-EDTA의 경우 약 56%로서 이는 Fenton-like 반응에 비하여 약 40-60% 정도의 제거효율이 향상된 결과이다.

• 한국물환경학회지
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• 제22권1호
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• pp.66-73
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• 2006

The purpose of this study was done to evaluate degradation characteristics of non-biodegradable organic matters including aromatic compounds in livestock wastewater using CFZ process. The CFZ process is consisted of coagulation/sedimentation, Fenton oxidation and zeolite adsoption process. degradation charateristics of each treatment water including livestock wastewater were analyzed by UV scanning, FT-IR and GC/MS. After coagulation/sedimentation process as 1st treatment, non-biodegradable matters remained after 1st treatment were removed by using OH radical produced in Fenton oxidation process. As a result of treatment using these processes, NBDCOD removal efficiency was over 90%. Increase of $E_2/E_3$ ratio (absorbance at 250 and 365 nm) in each treatment water means that aromaticity of livestock wastewater decreased. In case of GC/MS, most aromatics or polynuclear aromatics like benzene, phenol and scatol in livestock wastewater almost wasn't detected after oxidation using OH radical.