• Journal of the Korean Chemical Society
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• v.12 no.4
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• pp.139-141
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• 1968

The extraction curve of metal ions with Amberite LAl-chloroform has been found to be more steeper than with Amberite LAl-xylene or hexane, and the extraction ratio of Zn (II) in 2M HCl solution is 98%. The extraction ratio of As (III) in 9~11M HCl soln., Sb (III) in 2~4M HCl soln., and Fe (III) in 6~10M HCl soln. are 100%. The separated elements from Bi metal were determined by colorimetry, Zn (III) with dithizone, As (III) with Gutzeit method, Sb (III) with brilliant green and Fe (III) with thiocyanate.

• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.238-248
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• 2014

The metalloid arsenic (Z = 33) is considered to be a significant potential threat to human health due to its ubiquity and toxicity, even in rural regions. In this study a rural region contaminated with arsenic, located at longitude $85^{\circ}$ 32'E and latitude $25^{\circ}$ 11'N, was initially examined. Arsenic tolerant bacteria from the rhizosphere of Amaranthas viridis were found and identified as Bacillus licheniformis through 16S rRNA gene sequencing. The potential for the uptake and removal of arsenic at 3, 6 and 9 mM [As(V)], and 2, 4 and 6 mM [As(III)], and for the reduction of the above concentrations of As(V) to As(III) by the Bacillus licheniformis were then assessed. The minimal inhibitory concentrations (MIC) for As(V) and As(III) was determined to be 10 and 7 mM, respectively. At 3 mM 100% As(V) was uptaken by the bacteria with the liberation of 42% As(III) into the medium, whereas at 6 mM As(V), 76% AS(V) was removed from the media and 56% was reduced to As(III). At 2 mM As(III), the bacteria consumed 100%, whereas at 6 mM, the As(III) consumption was only 40%. The role of pH was significant for the speciation, availability and toxicity of the arsenic, which was measured as the variation in growth, uptake and content of cell protein. Both As(V) and As(III) were most toxic at around a neutral pH, whereas both acidic and basic pH favored growth, but at variable levels. Contrary to many reports, the total cell protein content in the bacteria was enhanced by both As(V) and As(III) stress.

• Economic and Environmental Geology
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• v.36 no.5
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• pp.349-356
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• 2003

As industrial activities are growing, pollutants found in the contaminated land are getting diverse. Some contaminated areas are subject to mixed wastes containing both organic and inorganic wastes such as hydrocarbon and heavy metals. This study concerns with the influence of the degradation of organic pollutants on the coexisting heavy metals, expecially for As. As mainly exists as two different oxidation state; As(III) and As(V) and the conversion between the two chemical forms may be induced by organic degradation in the soil contaminated by mixed wastes. We operated microcosm in an anaerobic chamber for 60 days, using sandy loam. The soils in the microcosm are artificially contaminated both by tetradecane and As, with different combination of As(III) and As(V); As(III):As(V) 1:1, As(III) only and As(V) only. Although not systematic, ratio of As(III)/As(Total) increase slightly at the later stage of experiment. Considering complicated geochemical reactions involving oxidation/reduction of organic materials, Mn/Fe oxides and As, the findings in the study seem to indicate the degradation of the organics is connected with the As speciation. That is to say, the As(V) can be reduced to As(III) either by direct or indirect influence induced by the organic degradation. Although Fe and Mn are good oxidising agent for the oxidation of As(III) to As(V), organic degradation may have suppressed reductive dissolution of the Fe and Mn oxides, causing the organic pollutants to retard the oxidation of As(III) to As(V) until the organic degradation ceases. The possible influence of organic degradation on the As speciation implies that the As in mixed wastes may be have elevated toxicity and mobility by partial conversion from As(V) to As(III).

• IMMUNE NETWORK
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• v.3 no.4
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• pp.276-280
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• 2003

Background: Peroxidases (Prx) of the peroxiredoxin family reduce hydrogen peroxide and alkyl hydroperoxides to water and alcohol respectively. Hydrogen peroxide is implicated as an intracellular messenger in various cellular responses such as proliferation and differentiation. And Prx I activity is regulated by Cdc-2 mediated phosphorylation. This work was undertaken to investigate the proliferation role of peroxiredoxin III as a member of Prx family in Prx III overexpressed HeLa cell line. Methods: To provide further evidence of proliferation, we selected Prx III stably expressed HeLa Tet-off cell lines. Cell proliferation was examined by using proliferation reagent WST-1 in the presence or absence of doxycycline. Prx III, 2-cys Prx enzymes exist as homodimer. The activation of Prx III heterodimer with induced and endogenous Prx III was examined by immunoprecipitation. Results: Immunoprecipitation analysis of the induced and endogenous Prx III with anti-myc showed that the induced wild type (WT) and dominant negative (DN) Prx III from HeLa Prx III Tet-off stable cell heterodimerized with endogenous Prx III each other. And the expression level of induced Prx III was examined after addition of doxycycline. By 72 hr, the expression level of induced Prx III was diminished gradually and the half-life of the induced wild type Prx III was approximately 17 hr. The proliferation experiment demonstrated that the relative proliferation value of induced and endogenous WT Prx III stable cell has no changes but the DN Prx III induced HeLa Tet-off stable cells were lower than endogenous Prx III. Conclusion: In conclusion, the HeLa dominant negative Prx III Tet-off stable cells were decreased the proliferation.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.7
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• pp.731-737
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• 2006

Four well-characterized soils collected from A- and B-horizon in the Department of Energy Oak Ridge Reservation in USA, mainly distributed with Inceptisol(Inc) and Ultisol(Ult) soils, were used in this work. The bioaccessibility of arsenic as well as oxidation phenomena of As(III) was investigated with soils spiked with As(III) and As(V) using a physiologically based extraction test(PBET) at pH 1.5 and 1:100 soil to solution ratio. Also effect of aging time on the bioaccessibility of arsenic was investigated over the 6 months. After 48 hours(fresh) contacting As(V) solution with soils, all soils rapidly and strongly sequestrated As(V), especially Ult-B. However, little sequestration was observed after 3-months. When As(III) was spiked on the same soils, a great portion of As(III) was oxidized to As(V) after 48 hrs, especially Inc-A and Ult-A soils, which is strongly related with Mn content in soils. By using As(III)-spiked soils, much reduced bioaccessibility as total arsenic was observed from Inc-B and Ult-B soils over the 6 months aging time compared to that from Inc-A and Ult-A soils. This result can be explained by the continuous sequestration of As(V), produced from oxidation of As(III), onto Inc-B and Ult-B soils having much amount of iron. The trend of As(III) sequestration over six months aging time was quite similar with that of As(V) sequestration.

• Journal of the Korean Applied Science and Technology
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• v.21 no.1
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• pp.76-88
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• 2004

The catalytic oxidation reaction of several cycloolefins in $CH_2Cl_2$ have been investigated using non-redox metalloporphyrin(M = Ga(III), In(III) and TI(III) complexes as a catalyst and sodium hypochlorite as a terminal oxidant. Porphyrins were $(p-CH_3O)$TPP, $(p-CH_3)$TPP, TPP, (p-F)TPP, (p-Cl)TPP and $(F_{20})$TPP (TPP=5,10,15,20-tetraphenyl-21H,23H-porphyrin) and olefins were cyclopentene, cyclohexene, cycloheptene and cyclooctene, The substrate conversion yield(%) was investigated according to the radius effect of non-redox metal ion, substituent effect and hindrance effect of metalloporphyrin. The conversion yield of cycloolefin was in the following order : $C_5$ < $C_6$ < $C_7$ = $C_8$.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.54-60
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• 2006

[ $MnO_2$ ]-Coated Sand(MCS) was prepared with variation of coating temperature, coating time, and dosage of initial Fe(III) with two kinds of sands such as Joomoonjin and quartz sand. An optimum condition for the preparation MCS was determined from the coating efficiency as well as the oxidation efficiency of As(III). Coating efficiency of Mn was strongly dependent on the coating temperature but quite similar over the investigated coating time, showing an increased coating efficiency at higher coating temperature. In contrast to coating efficiency, the oxidation efficiency of As(III) by MCS was severely reduced as increase of coaling temperature. By considering these results, an optimum coating temperature and time for the preparation of MCS was selected as $150^{\circ}C$ and 1-hr, respectively. Coating efficiency increased as the dosage of initial Mn(II) increased, while As(III) oxidation was maximum at 0.8 Mn(II) mol/kg sand. The solution pH was identified as an important parameter affecting stability of MCS, and dissolution of Mn from MCS increased as pH decreased. Oxidation rate of As(III) increased as the dosage of MCS increased as well as solution pH decreased.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.52-59
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• 2008

Adsorption is a major process causing the accumulation of arsenic onto soil. Therefore, further understanding of the adsorption/desorption characteristics of arsenic species on soil is essential for predicting their fate and preparing appropriate remediation strategy to remove arsenic from soil. In this study, the column adsorption/desorption experiment has been performed with As(III) and As(V) on soil. Experiment with As(III) was conducted under reducing condition, whereas that with As(V) was under oxidizing condition. Most of As(III) was remained on the oxidation state during the experiment. The results showed that the adsorption/desorption rate of As(III) was higher than that of As(V). Adsorption and desorption of arsenic species were not completely reversible in the column experiment. It was also found that As(V) in the column experiment was adsorbed more rapidly on soil than in the batch experiment.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.86.1-86.1
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• 2015

As the feature size of Si-based semiconductor shrinks to nanometer scale, we are facing to the problems such as short channel effect and leakage current. One of the solutions to cope with those issues is to bring III-V compound semiconductors to the semiconductor structures, because III-V compound semiconductors have much higher carrier mobility than Si. However, introduction of III-V semiconductors to the current Si-based manufacturing process requires great challenge in the development of process integration, since they exhibit totally different physical and chemical properties from Si. For example, epitaxial growth, surface preparation and wet etching of III-V semiconductors have to be optimized for production. In addition, oxidation mechanisms of III-V semiconductors should be elucidated and re-growth of native oxide should be controlled. In this study, surface preparation methods of various III-V compound semiconductors such as GaAs, InAs, and GaSb are introduced in terms of i) how their surfaces are modified after different chemical treatments, ii) how they will be re-oxidized after chemical treatments, and iii) is there any effect of surface orientation on the surface preparation and re-growth of oxide. Surface termination and behaviors on those semiconductors were observed by MIR-FTIR, XPS, ellipsometer, and contact angle measurements. In addition, photoresist stripping process on III-V semiconductor is also studied, because there is a chance that a conventional photoresist stripping process can attack III-V semiconductor surfaces. Based on the Hansen theory various organic solvents such as 1-methyl-2-pyrrolydone, dimethyl sulfoxide, benzyl alcohol, and propylene carbonate, were selected to remove photoresists with and without ion implantation. Although SPM and DIO3 caused etching and/or surface roughening of III-V semiconductor surface, organic solvents could remove I-line photoresist without attack of III-V semiconductor surface. The behavior of photoresist removal depends on the solvent temperature and ion implantation dose.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.3
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• pp.347-357
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• 2018

The applicability of room temperature ionic liquids (RTILs), 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([$C_nmim$] [$Tf_2N$]), was investigated for the extraction of Am(III) and Eu(III) from nitric acid using n-octyl(phenyl)-N,N-diisobutyl carbamoylmethyl phosphine oxide (CMPO) and tri-n-butylphosphate (TBP) as extractants. The distribution ratios of Am(III) and Eu(III) in CMPO-TBP/[$C_nmim$][$Tf_2N$] were measured as a function of various parameters such as the concentrations of nitric acid, CMPO, and TBP. The results were compared with those obtained in CMPO-TBP/n-dodecane (n-DD). With comparable concentrations of the extractants, the distribution ratios obtained with RTILs were much higher than those obtained with n-DD. It was observed that the extraction efficiency was less for Eu(III) than for Am(III). The extraction of Am(III) and Eu(III) decreased with increases in the feed acidity for all three RTILs. The results suggest that the extraction of Am(III) and Eu(III) by CMPO in RTILs from nitric acid proceeds through the cation-exchange mechanism. The distribution ratios of Am(III) and Eu(III) increased with increases in the concentration of CMPO for all three RTILs. A linear regression analysis of the extraction data resulted in a straight line with a slope of about 3, suggesting the involvement of 3 molecules of CMPO during the extraction process.