• Korean Journal of Microbiology
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• v.38 no.2
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• pp.133-138
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• 2002

Microbial Fe (III) reduction is important for the biogeochemical cycle in the sediment of freshwater system. Also, the Fe (III) reducing mechanism make a model of oxidizing organic compounds and reducing toxic heavy metals, such as chrome or uranium. Thirty-seven strains which have Fe (III) reducing activity were isolated from sediments in lake Soyang and Chunho reservoir. The initial concentration of Fe (II) was the highest in sediments of lake Soyang. However, the highest Fe (III) reducing activity was shown in Chunho reservoir. All isolates were tested for Fe (III) reducing activity. Strains C2 and C3, which were isolated from sediments of Chunho reservoir, showed the highest activity. These strains were tested to see if they utilize various electron donors such as glucose, yeast extract, acetate, ethanol and toluene. Significantly, glucose and yeast extract were used as electron donors. Also these strains were conformed to use humid acid and nitrate as electron accepters. The 16S rRNA sequences of strains C2 and C3 were closely related to Aeromonas hydrophila with 95% similarity.

• Journal of Microbiology and Biotechnology
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• v.19 no.8
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• pp.836-844
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• 2009

A denitrification bacterium was isolated from riverbed soil and identified as Ochrobactrum sp., whose specific enzymes for denitrification metabolism were biochemically assayed or confirmed with specific coding genes. The denitrification activity of strain G3-1 was proportional to glucose/nitrate balance, which was consistent with the theoretical balance (0.5). The modified graphite felt cathode with neutral red, which functions as a solid electron mediator, enhanced the electron transfer from electrode to bacterial cell. The porous carbon anode was coated with a ceramic membrane and cellulose acetate film in order to permit the penetration of water molecules from the catholyte to the outside through anode, which functions as an air anode. A non-compartmented electrochemical bioreactor (NCEB) comprised of a solid electron mediator and an air anode was employed for cultivation of G3-1 cells. The intact G3-1 cells were immobilized in the solid electron mediator, by which denitrification activity was greatly increased at the lower glucose/nitrate balance than the theoretical balance (0.5). Metabolic stability of the intact G3-1 cells immobilized in the solid electron mediator was extended to 20 days, even at a glucose/nitrate balance of 0.1.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2005.05a
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• pp.267-271
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• 2005

This experiment was carried out at 450"C, which is relatively lower than the temperature for supercritical water oxidation (600-650$^{\circ}C$). In this experiment, the decomposition rates of various incombustible organic substances were very high. In addition, it was confirmed that hetero atoms existed in organic compounds and chlorine was neutralized by sodium(salt formation).However, to raise the decomposition rate, relatively large amount of sodium nitrate(3-4 times the equivalent weight) was required. When complete oxidation is intended as in the case with PCB, the amount of oxidizer and decomposition cost is important. But when vaporization reduction is required as in the case with nuclear wastes, the amount of radioactive wastes increases instead. But as can be seen in the result of XRD measurement, unreacted sodium nitrate remained unchanged. If oxidation reaction of organic substance simply depends on collision frequency, unreacted sodium nitrate can be recovered and reused, then oxidation equivalent weight would be sufficient. In the gas generated, toxic gas was not found. As the supercritical water medium has high reactivity, it is difficult to generate relatively low energy level SO$_{X}$, and NO$_{X}$.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.575-595
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• 1997

Replacement resorption is followed by the delayed replantation of an avulsed tooth. Currently no effective treatment is substantiated for replacement resorption. The purpose of this study was to investigate the effect of stannous fluoride, bisphosphonate (etidronate disodium) and gallium nitrate, which have been shown to reduce dentin resorption, on human dentin. Osteoclasts were collected from tibeas of chick embryo. The cells were well agitated to prevent adhesion and seeded onto the sliced human dentin wafers which had been soaked in either culture media (control), or several different concentrations of stannous fluoride, etidronate disodium (l-hydroxyethylidene -1,1-bisphosphonate disodium), and gallium nitrate. Resorption was measured by counting the number of resorptive pit produced by the cells. Results are as follows. Stannous fluoride and etidronate disodium showed statistically significant reduction of dentin resorption(p<0.05) but the effect of stannous fluoride seemed to be its high cytotoxicity. Etidronate disodium did not show cytotoxicities in all experimented concentrations. Gallium nitrate did not show differences in resorption either between different concentrations or from the control group.

• Applied Biological Chemistry
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• v.29 no.2
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• pp.175-181
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• 1986

Eightyseven strains of indigenous Rhizobia were isolated from the nodule of soybean cultivar, Danyup, cultivated in four different soils sampled from continuously soybean cultivated and newly reclaimed fields. The strains were grouped into Bradyrhizobium japanicum (slow-grower:55 strains) and Rhizobium fredii (fast-grower: 32 strains). The both groups could be divided into two sub-groups according to the denitrification characteristics, that is, denitrifying fast-grower (F-I), nitrate respiring fast-grower (F-II), denitrifying slow-grower (S-I). and nitrate respiring slow-grower (S-II). Among the 87 isolates, F-I, F-II, S-I and S-II sub-groups were 10, 22, 48 and 7 strains, respectively. The one-and two-dimensional polyacrylamide gel electrophoretic pattern of the four sub-groups were compared and discernible difference was observed between fast and slow-grower, but the difference was not discernible between subgroups within the same growth rate group.

• Animal cells and systems
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• v.2 no.4
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• pp.455-462
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• 1998

A survey was conducted on the inorganic and organic solute patterns of plants in connection with nitrate metabolism according to different light regimes (1.9, 16.0, 91.5 $Wm^{-2}$). Besides measuring in vivo NRA, we also quantitatively analyzed ater-soluble inorganic ions, organic acids, low molecular weight carbohydrates, amino aciss and total N (% DW). Among 4 Carex species, C. pilosa is known as shade-adapted species and the others as half (C. gracilis) to full (C. rostrata & C. distans) light-adapted species. Compared to species adapted to high light intensity, shade-adapted C. pilosa showed reduced productivity under the highest light intensity. In general, nitrate and amino acid levels decreased at higher light intensity, while sugar and organic acid concentrations increased. In C. pilosa osmolality tended to rise with increasing light intensity, while in the other species it tended to fall. Under low light intensity, the drop in soluble carbohydrate contents is osmotically compensated for by an enhanced nitrate concentration. It is concluded that competition between nitrate and $CO_2$reduction for reductants and ATP from photosynthesis may have important ecological consequences for the adaptation of plants to low or high light conditions. Additionally, the patterns of ionic changes due to increased light intensities were essentially the same in all selected species, indicating similar characteristics of heir mineral ion and organic acid metabolism as well as in field-grown Carex species.

• Korean Journal of Materials Research
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• v.20 no.10
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• pp.508-512
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• 2010

The optimum route to fabricate nano-sized Fe-50 wt% Co and hydrogen-reduction behavior of calcined Fe-/Conitrate was investigated. The powder mixture of metal oxides was prepared by solution mixing and calcination of Fe-/Co-nitrate. A DTA-TG and microstructural analysis revealed that the nitrates mixture by the calcination at $300^{\circ}C$ for 2 h was changed to Fe-oxide/$Co_3O_4$ composite powders with an average particle size of 100 nm. The reduction behavior of the calcined powders was analyzed by DTA-TG in a hydrogen atmosphere. The composite powders of Fe-oxide and Co3O4 changed to a Fe-Co phase with an average particle size of 40 nm in the temperature range of $260-420^{\circ}C$. In the TG analysis, a two-step reduction process relating to the presence of Fe3O4 and a CoO phase as the intermediate phase was observed. The hydrogen-reduction kinetics of the Fe-oxide/Co3O4 composite powders was evaluated by the amount of peak shift with heating rates in TG. The activation energies for the reduction, estimated by the slope of the Kissinger plot, were 96 kJ/mol in the peak temperature range of $231-297^{\circ}C$ and 83 kJ/mol of $290-390^{\circ}C$, respectively. The reported activation energy of 70.4-94.4 kJ/mol for the reduction of Fe- and Co-oxides is in reasonable agreement with the measured value in this study.

• Journal of the Korean Applied Science and Technology
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• v.34 no.2
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• pp.217-224
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• 2017

This is a study on the removal of nitrate nitrogen from wastewater by oxidation and reduction reaction of zinc in an acidic atmosphere. The optimum removal rate of nitrate nitrogen and the optimum pH were studied by controlling the amount of zinc and sulfamic acid. The oxidation efficiency was higher at pH 2.0 in the range of pH 2.0 ~ 4.0 because the reaction occurred more strongly in strong acidic atmosphere. It is advantageous to reduce the nitrate ion to the final nitrogen gas by adding the sulfamic acid to the sulfurous acid because it consumes less $H^+$ ion than when the sulfamic acid is not present. According to the same amount of zinc, nitrate nitrogen was removed by 46.0% while sulfamic acid was not added, whereas nitrite nitrogen was removed by 93.0% by adding sulfamic acid. In addition, In this experiment, zinc was prepared in powder form and its reactivity was larger than that of other common zinc metal, so the removal efficiency was very high, about 80.0%, within one minute after the reaction.

• Korean journal of applied entomology
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• v.2
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• pp.16-21
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• 1963

The present study was undertaken to investigate the effects of different nitrogen source and rate on the growth of Fusarium oxysporum f. vasinfectum which is known to be a noticeable fungus causing the wilt disease of both sesame and cotton in Korea. From the results of this study, It was known that different N source and rate markedly affect the growth of Fusarium oxyspsrum f. vasinfectum Among four N sourses were used in this study, nitrate-N and urea-N were appropriate N source for the growth of fungus. Above all, nitrate N was the best N source because it is utilized in more extensive range of concentration in comparison with the other N source by the fungus, On the other hand, ammonia-N is of little avail for the growth of the fungus because of the formation of unusual colonies with wavy margin and bead-like mycelial cells in addition to marked reduction of mycelial growth and B sporulation of the fungus irrespective of concentration. Judging from the formation of such an abnormal colony and bead-like mycelial cell which is known to be a characteristic of 'staling-type' growth of fungi, the effect of ammonia-N on the growth of Fusarium oxysporum f. vasinfectum is similar to that of phenoxy componnds on some other fungi previously investigated by some workers. Ammonium and nitrate also was not considered to be an appropriate source for the growth of the fungus because of the formation of colonies with slight wavy margin and appreciable reduction of mycelial growth and sporulation in higher concentration than 50meq. , although much or less masking of the irregularity of colony occurs. Therefore, ammonia N alone or any other N combined with ammonia N is of little avail for the growth of Fusarium oxysporum f. vasinfectum.

• Elastomers and Composites
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• v.55 no.3
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• pp.191-198
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• 2020

Nickel oxide (NiO) nanoparticles were synthesized by a reaction of nickel nitrate hexahydrate (Ni(NO₃)₂·6H₂O) and sodium hydroxide (NaOH). The synthesized NiO nanoparticles were examined with X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and ultraviolet-visible (UV-vis) spectroscopy. The NiO nanoparticles were used as the catalyst for the reduction of o- and m-nitroaniline to phenylenediamine. The reduction rate of m-nitroaniline was faster than that of o-nitroaniline. The reduction rate for both o- and m-nitroaniline increased as the reaction temperature increased. The rate of reduction for nitroaniline followed a pseudo first-order reaction rate law.