• Corrosion Science and Technology
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• 제7권1호
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• pp.27-34
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• 2008

In industrial and fluid handling systems, frequently the protective film forming materials suffer from severe corrosion due to microbial effects. As an example, various micro-organisms, including bacteria, exist in seawater normally fed to power and desalination plants. Unless seawater intakes are properly disinfected to control these microbial organisms, biological fouling and microbial induced corrosion (MIC) will be developed. This problem could destroy metallic alloys used for plant construction. Seawater intakes of cogeneration plants are usually disinfected by chlorine gas or sodium hypochlorite solution. The dose of disinfectant is designed according to the level of contamination of the open seawater in the vicinity of the plant intake. Higher temperature levels, lower pH, reduced flow velocity and oxidation potential play an important role in the enhancement of microbial induced corrosion and bio-fouling. This paper describes, in brief, the different types of bacteria, mechanisms of microbiological induced corrosion, susceptibility of different metal alloys to MIC and possible solutions for mitigating this problem in industry. A case study is presented for the power plant steam condenser at Al-Taweelah B-station in Abu Dhabi. The study demonstrates resistance of Titanium tubes to MIC.

• Environmental Analysis Health and Toxicology
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• 제22권3호
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• pp.189-196
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• 2007

[ $TiO_2$ ] is widely used because it is non-toxic. Recently, however, nanometer size $TiO_2$ particles (P-25) have been produced and used to increase the photo catalysis efficiency. Nanometer-sized $TiO_2$ is efficient, but due to its small size ($20{\sim}30\;nm$), it can flow into ecosystems and into cells. Thus, it may affect human health. Additionally, $TiO_2$ can produce a second contaminant, OH-radical, which is a health risk for all living organisms during photo degradation reaction. Hence, when nanometer-sized $TiO_2$ flows into natural streams and attaches to living organisms, it will create health risks. We investigated the biological toxicity of this condition in zebrafish embryos. We observed abnormal morphology, hatching rate, and measured the catalase activity to determine anti-oxidation at 100 post fertilization hours. Zebrafish were somewhat affected by $TiO_2$ nanometer sized particles under UV-A (a condition similar to sunlight). Powdered $TiO_2$ is toxic to the zebrafish fly. Even without light, $TiO_2$ particles attached to embryos and flies, having an effect on both.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권3호
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• pp.82-93
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• 2014

A starch ball was devised to conveniently supply carbon source to indigenous microorganisms and to enhance biotransformation of explosive compounds(TNT and RDX) in the sediments of settling basins installed in military shooting ranges. To identify optimum dose/sediment ratio for degradation of explosives in the basin, a series of bench scale settling basin experiments were performed for 30 days while monitoring supernatant pH, DO, concentrations of nitrite, nitrate, sulfate, explosive compounds, and acute toxicity measured by bacterial luminescence. Addition of starch ball induced changes in oxidation conditions from oxic to anoxic in the benthic zone of the basin, which resulted in subsequent reductive degradation of both TNT and RDX in the liquid and solid phase of basin. However, fermentation products of excess starch, acetic acid and formic acid, caused acute toxicity in the liquid phase. The optimum ratio of starch ball/sediment for explosive compounds degradation by inducing changes in bio-geochemical environments without increase in acute toxicity, was found to be 0.009~0.017.

• Advances in environmental research
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• 제3권3호
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• pp.199-206
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• 2014

Dewatering is an extremely important step in wastewater treatment process to reduce the final sludge volume in order to minimize the cost of sludge transportation and disposal. In the present study, the effect of different sludge solids content (1, 2 and 3.8%) on the dewaterability of anaerobically digested sludge using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was studied. The pH reduction rate was higher during initial process in the sludge having low solids content, but after 48 h of bioleaching, similar pH of below 3 was observed with all the different solids content. Bio-oxidation rate of $Fe^{2+}$ was initially higher in sludge with low solids content, but 100% $Fe^{2+}$ was oxidized within 60 h in all the three treatment levels. Compared to the control, specific resistance to filtration was reduced by 75, 78 and 80% in the sludge with a solids content of 1, 2 and 3.8% respectively, showing improvement in dewaterability with an increase in sludge solids content. Sludge effluent quality and sludge settling rate were also improved in treatments with higher solids content after the bioleaching process.

• Environmental Engineering Research
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• 제24권3호
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• pp.501-512
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• 2019

The seasonal effects on the biostability of drinking water were investigated by comparing the seasonal variation of assimilable organic carbon (AOC) in full-scale water treatment process and adsorption of AOC by three filling materials in lab-scale column test. In full-scale, pre-chlorination and ozonation significantly increase $AOC_{P17\;(Pseudomonas\;fluorescens\;P17)}$ and $AOC_{NOX\;(Aquaspirillum\;sp.\;NOX)}$, respectively. AOC formation by oxidation could increase with temperature, but the increased AOC could affect the biostability of the following processes more significantly in winter than in warm seasons due to the low biodegradation in the pipes and the processes at low temperature. $AOC_{P17}$ was mainly removed by coagulation-sedimentation process, especially in cold season. Rapid filtration could effectively remove AOC only during warm seasons by primarily biodegradation, but biological activated carbon filtration could remove AOC in all seasons by biodegradation during warm season and by adsorption and bio-regeneration during cold season. The adsorption by granular activated carbon and anthracite showed inverse relationship with water temperature. The advanced treatment can contribute to enhance the biostability in the distribution system by reducing AOC formation potential and helping to maintain stable residual chlorine after post-chlorination.

• 멤브레인
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• 제34권2호
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• pp.96-104
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• 2024

항생제는 과도한 사용으로 인해 폐수뿐만 아니라 다양한 수원에서 발견되는 새로운 오염 물질 중 하나입니다. 수중 항생제 오염 물질을 처리하기 위한 고도 산화 공정, 생물학적 처리 등 다양한 기술이 있습니다. 이 두 가지 공정은 비효율적이며, 부산물의 생성은 이 공정을 더욱 복잡하게 만듭니다. 오염 물질을 제거하기 위한 또 다른 대안으로 막 기술이 있습니다. 항생제와 내성 유전자의 제거를 개선하기 위해 막 생물 반응기는 NaClO와 탄소 물질로 변형됩니다. 풍부한 반응성 종의 생성은 항생제의 내성 유전자에 대해 활성입니다.

• Asian-Australasian Journal of Animal Sciences
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• 제27권1호
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• pp.69-76
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• 2014

This study was carried out to evaluate the relationship between threonine (Thr) efficiency and Thr dehydrogenase (TDG) activity as an indicator of Thr oxidation on chicks fed with levels of diets (CP [17.5% and 21.5%] and Thr [3.8 and 4.7 g/100 g CP]; glycine [Gly][0.64% and 0.98%] and true digestible Thr [dThr] [0.45% and 0.60%]). Calculation of the Thr efficiency was based on N-balance data and an exponential N-utilization model, and TDG activity was determined as accumulation of aminoacetone and Gly during incubation of hepatic mitochondria. This study found that in the liver of chicks who received a diet containing up to 0.79% Thr (4.7 g Thr/100 g of CP) in the 17.5% CP diet, no significant (p>0.05) effect on TDG activity was observed. However, significantly (p = 0.014) increased TDG activity was observed with a diet containing 21.5% CP (4.7 g Thr/100 g of CP) and the efficiency of Thr utilization showed a significant (p = 0.001) decrease, indicating the end of the Thr limiting range. No significant (p>0.05) effect on the total TDG activity and accumulation of Gly was observed with addition of Gly to a diet containing 0.45% dThr. In addition, addition of Gly to a diet containing 0.60% dThr also did not result in a change in accumulation of Gly. Due to an increase in accumulation of aminoacetone, an elevated effect on total TDG activity was also observed. No significant (p>0.05) reduction in the efficiency of Thr utilization was observed after addition of Gly at the level of 0.45% dThr. However, significantly (p<0.001) reduced efficiency of Thr utilization was observed after addition of Gly at the level of 0.60% dThr. Collectively, we found that TDG was stimulated not only by addition of Thr and protein to the diet, but also by addition of Gly, and efficiency of Thr utilization was favorably affected by addition of Gly at the level near to the optimal Thr concentration. In addition, no metabolic requirement of Gly through the TDG pathway was observed with almost the same accumulation of Gly and a slight increase in TDG activity by addition of Gly. Thus, our findings suggest that determination of TDG activity and parameter of efficiency of Thr utilization may be useful for evaluation of dietary Thr level.

• 생명과학회지
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• 제25권9호
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• pp.1014-1020
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• 2015

㈜한국바이오솔루션에서 제공받은 쌀겨발효 추출물(Fermented Rice-Bran, FRB)과 현재 시판 중에 있는 제품의 주원료로 사용되고 있는 미배아대두발효 추출물(Fermented Rice-Soybean, FRS)을 대조군으로 in vitro상에서의 이 화학적 특성과 생리활성 및 항산화작용에 대하여 검토하였다. 이화학적 특성으로 총 폴리페놀 화합물과 flavonoid 함량을 측정하였고, 생리활성 및 항산화작용은 DPPH 자유라디칼 소거활성, Fe/Cu 환원력, 간장 microsome을 이용한 지질 과산화 억제활성, linoleic acid 산화 실험계를 이용하여 측정하였다. 쌀겨발효 추출물의 총 폴리페놀과 flavonoids 함량은 각각 19.92 mg/g과 11.56 mg/g으로 미배아대두발효 추출물보다 높은 수치를 보였다. 쌀겨발효 추출물은 DPPH free radical 소거 활성능에서도 69.8%로 상당히 높은 소거율을 나타내었으며 환원력 또한, 처리농도 증가와 함께 높아지는 경향을 보였다. 간장 microsome을 이용한 지질 과산화 억제활성, linoleic acid 산화 실험계를 통한 지질과산화 억제활성을 확인한 결과, 쌀겨발효 추출물이 미배아대두발효 추출물보다 우수함을 확인하였다. 따라서, 본 연구는 건강식품소재 개발을 위해 쌀겨발효 추출물의 생리활성물질과 항산화 활성을 검토하는 기초 자료로 활용될 수 있을 것이라 사료된다.

• 한국식품영양과학회지
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• 제38권8호
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• pp.977-982
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• 2009

비파엽 열수추출물을 이용하여 항산화성과 항히스타민 및 항염증 효과를 조사하였다. 비파엽 열수추출물의 총 폴리페놀 함량은 28.91$\pm$2.1 mg/g, 총 플라보노이드 함량은 10.54$\pm$4.6 mg/g으로 분석되었다. 전자공여능은 400 $\mu g$/mL 에서 81.04$\pm$1.55%로 가장 높았으며, 아질산염 소거능은 pH 1.2($49.52\pm1.04\sim72.52\pm$0.84%)> pH 4.2($35.28\pm0.78\sim51.20\pm$1.10%)> pH 6.0($27.90\pm0.36\sim32.26\pm$1.20%) 순으로 pH가 낮을수록 비파엽 열수추출물 농도가 높을수록 높았다. 비파엽 열수추출물 100, 200, 300 $\mu g$/mL에서 $\beta$-hexosaminidase 방출 억제능은 각각 14.58$\pm$0.97%, 43.69$\pm$0.96%, 95.58$\pm$0.75%로 농도에 의존적으로 증가하였다. 비파엽 열수추출물을 이용하여 RAW cell을 대상으로 항염증 활성을 조사한 결과, 농도가 증가함에 따라 증가하여 400 $\mu g$/mL에서 44.35$\pm$0.63%를 나타내어 다양한 생리활성을 보여주었다.

• 한국식품영양과학회지
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• 제44권3호
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• pp.331-337
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• 2015

감귤류와 감귤류의 과피는 오랜 기간 동양의학의 약재로 사용되어 왔고 최근에는 생과와 주스로 많이 소비되고 있다. 하지만 감귤류 가공 공정 시 많은 과피 부산물이 발생하므로 활용방안이 필요하다. 감귤류의 과피에는 플라바논(flavanone)이 풍부하며 이 플라바논의 형태 중 배당체보다 비배당체의 체내 흡수가 더 효과적이므로 비배당체가 생리적 효과가 더 뛰어나다. Bioconversion(물질전환)은 cytolase에 의해 narirutin과 naringin은 naringenin으로, hesperidin은 hesperetin으로 각각 전환되며, 본 연구는 감귤의 과피에 다량 존재하는 플라바논을 물질전환 한 뒤 면역세포에서 항산화 및 항염증 효과를 확인하였다. 물질전환 후에 감귤 과피 추출물의 전자공여능이 농도 의존적으로 높아지는 것을 확인하였고, 면역세포인 RAW264.7에 200, $500{\mu}g/mL$ 감귤 bioconversion 전(CU) 후(CU-C) 과피 추출물을 4시간 동안 처리한 후 LPS($1{\mu}g/mL$, 8시간)를 처리하였다. 염증 관련 효소인 iNOS와 COX-2의 mRNA와 단백질 발현을 확인한 결과 물질전환과 관계없이 감귤 과피 추출물이 LPS에 의해 유도된 iNOS와 COX-2의 mRNA와 단백질 발현을 농도 의존적으로 감소시켰지만 물질전환 전보다 후 추출물의 억제 효과가 더 높았다. iNOS에 의해 생성되는 NO 역시 감귤 과피 추출물이 LPS에 의해 유도된 NO 생성을 억제시켰다. 본 연구 결과는 감귤 과피 추출물이 항산화와 항염증 생리활성을 보였지만 cytolase를 이용하여 물질전환 한 감귤 과피 추출물이 물질전환 전보다 이러한 생리활성이 강화됨을 보임으로써 향후 감귤류 부산물로 폐기되어온 감귤류 과피가 산화적 스트레스와 염증반응에 기인하는 만성질환을 위한 기능성 소재로 활용이 가능할 것으로 기대된다. 감귤 과피 추출물의 in vitro 상에서 검증된 항염증 효능이 향후에 in vivo 상에서 여러 염증 조직에 미치는 영향에 대한 추가 검증이 필요하다고 사료된다.