• Journal of Microbiology and Biotechnology
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• 제18권7호
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• pp.1298-1307
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• 2008

In this study, we investigated the inhibition effects of single and mixed heavy metal ions ($Zn^{2+},\;Ni^{2+},\;Cu^{2+},\;and\;Cd^{2+}$) on iron oxidation by Acidithiobacillus ferrooxidans. Effects of metals on the iron oxidation activity of A. ferrooxidans are categorized into four types of patterns according to its oxidation behavior. The results indicated that the inhibition effects of the metals on the iron oxidation activity were noncompetitive inhibitions. We proposed a reduced inhibition model, along with the reduced inhibition constant ($\alpha_i$), which was derived from the inhibition constant ($K_I$) of individual metals and represented the tolerance of a given inhibitor relative to that of a reference inhibitor. This model was used to evaluate the toxicity effect (inhibition effect) of metals on the iron oxidation activity of A. ferrooxidans. The model revealed that the iron oxidation behavior of the metals, regardless of metal systems (single, binary, ternary, or quaternary), is closely matched to that of any reference inhibitor at the same reduced inhibition concentration, $[I]_{reduced}$, which defines the ratio of the inhibitor concentration to the reduced inhibition constant. The model demonstrated that single metal systems and mixed metal systems with the same reduced inhibitor concentrations have similar toxic effects on microbial activity.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.175-176
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• 2006

The filling property of the binder treated iron based powder made of atomized iron powder was compared with that of the one made of reduced iron powder. The latter one showed a better filling property than the former one, although the original reduced powder showed a worse flow rate. Changing the particle size distribution of the original atomized powder from wide to narrow like the original reduced iron powder, improved the filling property of the binder treated powder. As a result, the particle size distribution of the original iron powder was found to strongly affect the filling property of the binder treated powder.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.173-174
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• 2006

X-ray analysis on iron ores and reduced iron powders revealed that the main acid-insoluble substances were hexagonal and tetragonal quartz, another substances were sillimanite, alumina-silicate, an unnamed zeolite, all contained Si and Al. Their particle size was in the range of $3{\sim}7\;{\mu}m$. Statistics analysis showed that the AIC for high-grade magnetite powder was $(0.130{\pm}0.010)%$) during the latest five months. The predicting value for reduced iron powder should be 0.179%. However, the testing value for reduced iron powder was $(0.192{\pm}0.014)%$. The limited difference of 0.013% might imply rare pollution coming from the reduction and milling processes. The most important step for control AIC should be the separation process of iron ore powders.

• 대한환경공학회지
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• 제27권2호
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• pp.123-129
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• 2005

철을 이용한 반응벽체 (permeable reactive barrier, PRBs) 기술은 유기 화합물로 오염된 지하수를 환원적 반응에 의해 정화시키는 공법이다. 벽체의 매질로 주로 사용되는 영가 철은 반응이 진행됨에 따라 점차 2가 및 3가 철로 산화되어 제거능이 점차 저감된다. 자연계에 존재하거나 동정된 철 환원 박테리아는 산화된 Fe(III)를 Fe(II)로 환원시키는 능력을 가지고 있으며 이와 같이 환원된 Fe(II)는 반응 표면적을 넓히고 다시 할로겐 유기 화합물을 환원적으로 제거할 수 있도록 한다. 본 연구는 철 환원 박테리아로 순수균인 Shewanella algae BrY에 의한 산화철의 환원 경향을 aqueous phase와 solid phase로 나누어 관찰하고 환원된 철이 TCE 제거에 미치는 영향을 iron(II,III) oxide와 iron(III) oxide를 대상으로 하여 파악하는 것을 목표로 하였다. 박테리아는 배지 내에 존재하는 Fe(III)를 우선적으로 사용하여 Fe(II)로 환원시켰으며 선택성은 떨어지지만 입자상의 산화철 표면에 존재하는 Fe(III)도 환원시켰다. 또한 동량의 산화철이 존재할 때 iron(II,III) oxide에 비해 박테리아가 전자수용체로 사용할 수 있는 Fe(III)가 풍부한 iron(III) oxide의 환원이 더 잘 일어남을 알 수 있었고, 환원된 Fe(II)는 박테리아 또는 다른 철 산화물과 침전을 형성하였으며 TCE와의 반응속도 및 제거 능력을 향상시키는 것으로 판단된다.

• 한국세라믹학회지
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• 제52권5호
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• pp.389-394
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• 2015

Direct reduced iron was made using an electric furnace. The reduction ratio of direct reduced iron varied depending on the grade of iron ore. Coal played an important role as a reducing agent in making the direct reduced iron. The coal must contain a suitable amount of volatile components having high calorie values and low impurity content. In this study, oxidized pellets were directly reduced using anthracite as a reductant in an electric furnace. Direct reduction behaviors of hematite and magnetite pellets were confirmed in a coal-based experiment. Reduction behaviors were demonstrated by analyzing the chemical compositions, measuring the reducibility, and observing the phase changes and microstructure. The superior reducibility of hematite pellets can be ascribed to their high effective diffusivity, which is due to their high porosity. The quickly after reducing for 40min and achieves a high value at the end of the reduction.

• 대한핵의학회지
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• 제3권2호
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• pp.1-16
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• 1969

The double tracer study on erythrokinetics was carried out experimentally with radioactive iron ($^{59}Fe$) and chromium ($^{51}Cr$) in rabbits. The 0.1% canthalidin solution and 1% pot. perchlomate solution was given subcutaneously to 20 rabbits respectively. 3 and 6 days after injection, the blood chemistry, urine examination, ferrokinetics and apparent half survival time of RBC were ($^{51}Cr\;T\frac{1}{2}$)determined. Following were the results: 1) Red blood cell hematocrit and hemoglobin values were moderately reduced and B.U.N. and serum creatinine values were slight]y inercased in the canthalidin group, while B.U.N. and serum creatinine values were within normal limits in the pot. perchlomate group. Reticulocyte values were slight]y increased in the canthalidin group, while was normal range in the pot. perchlomate group. 2) Blood chemistry finding was not significant statistically in both experimental groups, but serum iron value was moderately reduced in both group. 3) Plasma volume was unchanged in both group, but red cell volume and whole blood volume were slightly reduced in both groups. 4) Results of ferrokinetics were as follows: i) The plasma iron disappearance rate was delayed in both groups. Plasma iron turnover rate, red cell iron utilization and red cell iron turnover rate were decreased in both groups, and then red cell iron turnover rate was more decreased than plasma iron turnover rate in both groups. Circulating red cell iron was slight]y increased in canthalidin group and red cell iron concentration was within normal range in both groups. ii) P.I.T.R.-R.C.I.T. value was moderately increased in the canthalidin group and slightly increased in the pot. perchlomate group. Reticulocyte index, red cell iron turnover index, plasma iron turnover index and effective erythropoiesis index were whole]y reduced in both groups. iii) The red cell life span was slightly shortened in the canthalidin group while was within normal range in pot. perchlomate group. The pathologic finding of renal biopsy of the canthalidin group shows a selective damage in glomerulus, while shows almost normal range or slight damage in tubules. And that of the pot. perchlomate group shows a selective damage in tubules with slight damage of glomerulus.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.250-253
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• 2002

Remediation of groundwater using zero valent iron filings has received considerable attention in recent years. However, zero valent iron is gradually transformed to iron(III) oxides at permeable reactive barriers, so the reduction of iron(III) oxides can enhance the longevity of the reactive barriers. In this study, microbial reduction of Fe(III) was performed in anaerobic condition. A medium contained nutrients similar to soil solution. The medium was autoclaved and deoxygenated by purging with 99.99% $N_2$ and pH was buffered to 6, while the temperature was regulated as 2$0^{\circ}C$. Activity of iron reducing bacteria were not affected by chlorinated organics but affected by iron(III) oxide. Although perchloroethylene(PCE) was not degraded with only ferric oxide, PCE was reduced to around 50% with ferric oxide and microorganism. It shows that reduced iron can dechlorinate PCE.

• 대한핵의학회지
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• 제2권1호
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• pp.27-41
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• 1968

The ferrokinetics and red cell life spans of the patients with chronic glomerulonephritis were investigated by the double tracing method using radioactive iron ($^{59}Fe$) and chromium ($^{51}Cr$). According to the serum NPN levels, the patients were subdivided into 3 groups: Group 1. 6 patients, had the levels below 40 mg/dl Group 2. 6 patients, had the levels between 41 mg/dl to 80 mg/dl Group 3. 10 patients, had the levels above 80 mg/dl The results were as follows: 1) Red blood cell-, hematocrit- and hemoglobin values were moderately reduced in patients with normal serum NPN levels, while markedly reduced in patients with elevated serum NPN levels. 2) The plasma volume was increased, while the red cell volume was decreased in patients with elevated serum NPN levels, hence, total blood volume was unchanged. 3) The serum iron level was slightly reduced h patients of groups 1 and 2, while was within the normal ranges in patients of group 3. 4) i) In patients with normal serum NPN levels, the plasma iron disappearance rate, red cell iron utilization rate, red cell iron turnover rate, daily red cell iron renewal rate, circulating red cell iron and red cell iron concentration were within the normal ranges, while the plasma iron turnover rate was slightly reduced. ii) In patients with elevated serum NPN levels, the plasma iron disappearance rate was delayed, while the plasma iron turnover rate was within the normal ranges. The red cell iron utilization rate, red cell iron turnover rate and circulating red cell iron were decreased and the period in which the red cell iron utilization rate reachd its peak was delayed in Group 3 patients. The daily red cell iron renewal rate and the red cell iron concentration were unchanged. iii) The mean red cell life span was within the normal ranges in patients with normal serum NPN levels, while was shortened in patients with elevated serum NPN levels.

• 대한수의학회지
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• 제41권3호
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• pp.305-310
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• 2001

Iron deficient anemia in piglets could be overcome by supplementary iron. Overloaded iron induced peroxidation of cell membrane and increased malonaldehyde (MDA). Antioxidant activity of vitamin C has been studied in iron-overloaded swine plasma. Erythrocyte fragility, MDA, glutathione, vitamin A, and vitamin E were measured in swine plasma with or without iron (0~1mg/dl) and vitamin C (0~10mg/dl). Erythrocyte fragility increased from 8% to 45% in iron group and reduced from 57% to 43% in vitamin C group with dose dependant response. MDA was $0.94{\pm}0.05$ and $1.86{\pm}0.10$ nmol/ml in piglet and pig, respectively, and significantly high in pig (p<0.05). Iron increased MDA from $1.86{\pm}0.10$ to $9.46{\pm}0.04$ nmol/ml in pig, but not in piglet (p<0.05). Vitamin C reduced MDA from $9.46{\pm}0.04$ to $4.80{\pm}0.10$ nmol/ml in pig. Iron increased glutathione from $90.12{\pm}0.10$ to $108.52{\pm}5.29$ nmol/dl in pig, and vitamin C reduced glutathione from $108.52{\pm}5.29$ to $93.52{\pm}2.44$ nmol/dl (p<0.05). Vitamin A and E were $24.86{\pm}2.70$ to $138.29{\pm}6.70{\mu}g/dl$, respectively in iron group, and $35.76{\pm}0.60$ to $177.21{\pm}2.95{\mu}g/dl$, respectively in supplementary vitamin C group (p<0.05). These data indicated an antioxidant activity of vitamin C in iron-overloaded swine plasma.

• Animal cells and systems
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• 제14권2호
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• pp.91-98
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• 2010

Male rats were given a single injection of iron, and temporal changes in iron content and iron-induced effects were examined in heart cellular fractions. Over a period of 72 h, the contents of total and labile iron, reactive oxygen species, and NO in tissue homogenate, nuclear debris, and postmitochondrial fractions were mostly constant, but in mitochondria they continuously increased. An abrupt decrease in membrane potential and NAD(P)H at 12 h was also found in mitochondria. The respiratory control ratio was reduced slowly with a slight recovery at 72 h, suggesting uncoupling by iron.While the ATP content of tissue homogenate decreased steadily until 72 h, it showed a prominent increase in mitochondria at 12 h. Total iron and calcium concentration also progressively increased in mitochondria over 72 h. Enzyme activity of the oxidative phosphorylation system was significantly altered by iron injection: activities of complexes I, III, and IV were reduced considerably, but complex II activity and the ATPase activity of complex V were enhanced. A reversal of activity in complexes I and II at 12 h suggested reverse electron transfer due to iron overload. These results support the argument that mitochondrial activities including oxidative phosphorylation are modulated by excessive iron.