• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.949-954
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• 2012

This study is conducted to evaluate the effects of chelating agents for improving plant growth and reusing accumulated nutrients in soils of plastic film house. Two experiments were carried out at follows: i) The incubation test was conducted using soils treated with 0, 300 mM of EDTA and DTPA to examine the availability of nutrients. ii) For the pot test, chinese cabbages were cultivated in soils with 0, 0.1, 0.5, 1, and 5 mM of EDTA and DTPA to examine the impacts of plant growth response. The application of chelating agents increased ther availability of soil nutrients in the following order: DTPA > EDTA > control. Inorganic concentration of chinese cabbages in DTPA treatments consderably increased in nitrogen, phosphate, iron and aluminium contents than that of the other treatments. The optimal concentration of DTPA for vigorous plant growth as 0.5 mM. Thus, DTPA was more effective than other chelating agents for healty growth of cabbages and the availability of nutrients accumulated in plastic film house.

• Bulletin of the Korean Chemical Society
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• v.29 no.7
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• pp.1327-1331
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• 2008

Novel $CO_2$-soluble 8-hydroxyquinoline (8-HQ) chelating agents were synthesized and evaluated for solubility and metal ion extraction ability in supercritical $CO_2\;(Sc-CO_2)$. Among them, secondary amide-containing 8- HQ derivatives cannot be dispersed well into Sc-$CO_2$, but tertiary amide-containing derivatives can dissolve completely in Sc-$CO_2$ even at low CO2 pressures, perhaps owing to the predominant intermolecular interaction between the chelating agent and the $CO_2$ molecule. Based on 8-HQ chelating agent solubility data, we investigated the extraction of metal ions ($Co^{2+}$, $Cu^{2+}$, $Sr^{2+}$, $Cd^{2+}$, and $Zn^{2+}$) using two highly $CO_2$-soluble 8-HQ derivatives (4d, 4e) in Sc-$CO_2$. The extraction efficiency of tertiary amide-containing 8-HQ ligands, both fluorinated and non-fluorinated forms, was dramatically increased in the presence of diethyl amine (organic base). We suggest that diethyl amine could play an important synergistic role in the stronger metal binding ability of 8-HQ through an in situ deprotonation reaction in Sc-$CO_2$ medium.

• Journal of Ginseng Research
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• v.31 no.3
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• pp.154-158
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• 2007

In order to increase the content of germanium in ginseng adventitious roots, the effects of chelating agents on germanium content and root growth were investigated in the submerged cultures of ginseng adventitious roots. Chelating agents such as citric acid, oxalic acid, phosphoric acid, EDTA (Ethylenediamine tetraacetic acid) or EGTA (Ethylene glycol-bis $({\beta}-aminoethylether)-tetraacetic$ acid) were administrated in the submerged culture of ginseng root containing 50 ppm $GeO_2$. After 6 weeks of cultivation, fresh weight, germanium and saponin contents in the roots were analyzed. Among chelating agents, addition of 1.0mM phosphoric acid was found to be best for germanium accumulation. Under this condition, germanium content increased 1.4 times as compared to that of the control. The germanium content in the adventitious roots also increased with addition of EDTA or EGTA, while they inhibited the growth of ginseng adventitious root. Citric and oxalic acids were not effective for increasing germanium content in adventitious roots. As the results, it suggests that the phosphoric acid can be proved as the optimal agent for the enhancement of germanium accumulation in ginseng adventitious roots. These results can be served as a guideline for the mass production of ginseng adventitious roots containing germanium by large-scale production.

• Food Science and Biotechnology
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• v.17 no.1
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• pp.114-117
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• 2008

Chelating agents to sand lance fish sauce for the prevention of precipitate formation were applied. The precipitates consisted of crude protein (74.4%), ash (18.7%), and other components (6.9%). Sand lance sauce was mainly composed of glutamic acid (3.69 mg/g), alanine (2.96 mg/g), and lysine (2.64 mg/g). However, there was an increase in the amount of hydrophobic amino acids, phenylalanine, isoleucine, and leucine, in the precipitates. Sodium ions were not detected in the precipitate; rather, the main elements were Mg ($1.98{\times}10^4\;{\mu}g/g)$, K ($1.36{\times}10^4\;{\mu}g/g)$, and Ca ($6.66{\times}10^2\;{\mu}g/g)$. In HPLC analysis, fish sauce was composed of 2 main peaks with molecular weights of 85.5 and 528.4 Da, respectively. However, the precipitate contained one peak with a molecular weight of 1,513.5 Da. The addition of 0.2% malic acid and citric acid caused 55 and 70% prevention of the precipitate, respectively. Citric acid was the most effective chelating agent and efficiently prevented precipitation in the fish sauce.

• Corrosion Science and Technology
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• v.16 no.2
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• pp.59-63
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• 2017

Chelating solutions can be damaged by strong acids during oil production. To design effective corrosion inhibitors and other alternatives for corrosion control, it is important to understand not only the behavior of the system under operating condition but also the kinetics of electrochemical reactions during the corrosion process. In this study, the electrochemical behaviors of P-110 steel in aqueous fluids based on ethylenediaminetetraacetic acid (EDTA) compounds under various temperatures and hydrodynamic regime conditions were assessed. Electrochemical measurements were conducted using rotating disc electrodes manufactured. Electrolytes were prepared using aqueous compounds of EDTA like diammonium salt, disodium salt, and tetrasodium salt. Potentiodynamic polarization, electrochemical impedance, and mass loss tests were performed in order to assess the corrosion kinetic in electrolytes. Hydrodynamic effects were observed only in the cathodic polarization curve. This proves that hydrodynamic regime plays an important role in the corrosion of steel mainly in disodium and diammonium EDTA solutions. Two cathodic reactions controlled the corrosion process. However, oxygen level and pH of the electrolyte played the most important role in metal corrosion. Corrosion rates in those fluids were decreased drastically when oxygen concentration was reduced.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.5
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• pp.99-106
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• 2008

Metal ions such as Cu and Cr were extracted from the Cu, Cr and Ag impregnated active carbon by contacting the solid surfaces with supercritical carbon dioxide(Sc-$CO_2$) containing chelating agents. About 10g of the active carbon sample were loaded in a vertical tube extractor contacting with $CO_2$ flowing from the bottom of the tube for 6hrs. The ligands used were acetyl acetone(AA) and Cyanex-302(C-302). Water and methanol were used as entrainers to study the effect of co-solvent to $CO_2$. Experimental results showed that C-302 was more effective than AA in removing Cu with the maximum extraction of 42.0wt%, while 57.6wt% of Cr was extracted with AA from the sample.

• Corrosion Science and Technology
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• v.11 no.3
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• pp.82-88
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• 2012

The thickness and chemical composition of oxides on heat recovery steam generator tubes of combined cycle power plant were examined in order to evaluate the corrosion of the tubes. Tubes were removed from the plant after actual operations for 21,482, 42,552 and 56,123 hours respectively. Thickness and growth rate of the oxide scale on reheater inner tube (SA213-T22) were very high compared to those other tubes. The oxide scale was about $250{\mu}m$ thick and uniform. The components of the scale were iron oxides. The oxide scale was mixed oxides consisting of magnetite$(Fe_3O_4)$ and hematite$(Fe_2O_3)$. The oxide on inner tube was removed using many kinds of chemicals and it was found that chelating agents were dissolved faster than other chemicals.

• Archives of Pharmacal Research
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• v.11 no.2
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• pp.81-86
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• 1988

The transfer of cupric sulfate across the rat small intestine in vitro was studied by perfusion method using the segments of everted rat small intestine. Copper transport was approximately propotional to the metal concentration in the mucosal solution and no difference was observed in the metal transport among rat duodenum, jejunum and ileum. It was suggested from these results that copper transport across the rat small intestine would occur by passive diffusion. The effect of various chelating agents on copper transport across the rat small intestine n vitro and its uptake by the intestine were also studied. Copper transport was greatly enhanced in the presence of EDTA and NTA. Copper uptake decreased to a greater extent in the presence of EPTA and NTA.

• Journal of Powder Materials
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• v.30 no.5
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• pp.394-401
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• 2023

Li_1.5Al_0.5Ti_1.5(PO₄)₃ (LATP) is considered to be one of the promising solid-state electrolytes owing to its excellent chemical and thermal stability, wide potential range (~5.0 V), and high ionic conductivity (~10^-4 S/cm). LATP powders are typically prepared via the sol-gel method by adding and mixing nitrate or alkoxide precursors with chelating agents. Here, the thermal properties, crystallinity, density, particle size, and distribution of LATP powders based on chelating agents (citric acid, acetylacetone, EDTA) are compared to find the optimal conditions for densely sintered LATP with high purity. In addition, the three types of LATP powders are utilized to prepare sintered solid electrolytes and observe the microstructure changes during the sintering process. The pyrolysis onset temperature and crystallization temperature of the powder samples are in the order AC-LATP > CA-LATP > ED-LATP, and the LATP powder utilizing citric acid exhibits the highest purity, as no secondary phase other than LiTi₂PO₄ phase is observed. LATP with citric acid and acetylacetone has a value close to the theoretical density (2.8 g/cm³) after sintering. In comparison, LATP with EDTA has a low sintered density (2.2 g/cm³) because of the generation of many pores after sintering.

• Journal of Preventive Medicine and Public Health
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• v.7 no.2
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• pp.377-381
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• 1974

Determination of lead in urine is important in industrial hygiene and toxicology. Dithizone method has been principally used for the determination of lead in urine, which gives accurate results in skilful hands but is usually complex and time-consuming. Atomic absorption spectrophotometry is a new simple method and several procedures have been described. However, the influences of pH and the presence of chelating agents during treatment of lead poisoning are not clear. The purpose of this study was to find out the effect of pH and chelating agents on the determination of lead using Shimadzu atomic absorption/flame spectrophotometer, model AA-610. The results obtained were as follows: 1. The atomic absorption spectrophotometry(AAS) could be applied without prior acid digestion to specimens in the absence of chelating agents. The absorbance at $2,170\;{\AA}$, though more sensitive, was more noisy electronically. Therefore, we selected the wavelength of $2,833\;{\AA}$ plus scale expansion. 2. The optimal pH was in the range from 2 to 3. 3. The sensitivity was $0.075{\mu}g/ml/%$ and detection limit was about $0.2{\mu}g/ml$. 4. In the presence of EDTA, lead could not be completely determined without prior acid digestion. 5. On specimens from patients receiving penicillamine therapy, a comparison was made between the values obtained with dithizone method and AAS method with prior acid digestion. The results of comparison showed a very good agreement.