• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.421-425
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• 2001

Among the many parameters describing water quality, total nitrogen content(TN) is regarded as important one in relation to water quality management of the waterbodies for its role in eutrophication process. This study evaluated for accuracy, convenience and promptness of nitrogen analysis methods : (1)UV spectrophotometric method, (2)summation method, (3)cadmium reduction method. And, the detection limit of each method was calculated using EPA method. The UV spectrophotometric method after oxidation appears to be more convenient and accurate in determination of the TN contents than the summation method and cadmium reduction method. The summation method is necessary to separate determinations of the organic nitrogen, ammonia, nitrite, and nitrate. And, because summation method has many other methods for each contents, it can be detected for wide range of concentration.

• Journal of Plant Biotechnology
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• v.48 no.3
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• pp.124-130
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• 2021

Nitrate is an important nutrient and signaling molecule in plants that modulates the expression of many genes and regulates plant growth. In this study, we cover the research status of transcription factors related to the control of gene expression by nitrate signaling in higher plants. Nitrate reductase is a key enzyme in nitrogen assimilation, as it catalyzes the nitrate-to-nitrite reduction process in plants. A variety of factors, including nitrate, light, metabolites, phytohormones, low temperature, and drought, modulate the expression levels of nitrate reductase genes and nitrate reductase activity, which is consistent with the physiological role if. Recently, several transcription factors controlling the expression of nitrate reductase genes have been identified in higher plants. NODULE-INCEPTION-Like Proteins (NLPs) are transcription factors responsible for the nitrate-inducible expression of nitrate reductase genes. Since NLPs also control the nitrate-inducible expression of genes encoding the nitrate transporter, nitrite transporter, and nitrite reductase, the expression levels of nitrate reduction pathway-associated genes are coordinately modulated by NLPs in response to nitrate. Understanding the function of nitrate in plants will be useful to create crops with low nitrogen use.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.53-60
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• 2005

Ferrous cement hydrates made from hydrating Portland cement doped with Fe (II) were reported to reductively dechlorinate chlorinated organics and to reduce Cr (VI) to Cr (III). In this study, kinetics of nitrate removal by ferrous cement hydrates were investigated. Nitrate removal kinetics were characterized by experimental variables such as cement hydration, amount of cement addition, Fe (II) dose, pH, and byproducts. As a result, hydrated cement showed better performances than non-hydrated cement due to the formation of LDH (layered double hydroxide). Doping of Fe (II) into the cement was found to improve removal efficiency at high pHs by association with Fe (II) sorbed on cement hydrates as a reactive reductant. Reduction of nitrate produced ammonium as a major product, which accounted for 63.5% of the final products, and nitrite (0.15%) as a minor product. These results indicate that the developed media are effective as sorbent/reducing agents in the nitrate removal and the reaction mechanisms of nitrate removal are sorption and reduction.

• Membrane and Water Treatment
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• v.11 no.2
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• pp.167-172
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• 2020

The effectiveness of in situ sediment capping as a technique for heavy metal risk mitigation in Hyeongsan River estuary, South Korea was studied. Sites in the estuary were found previously to show moderate to high levels of contamination of mercury, methylmercury and other heavy metals. A 400 m x 50 m section of the river was selected for a thin layer capping demonstration, where the total area was divided into 4 sections capped with different combinations of capping materials (zeolite, AC/zeolite, AC/sand, zeolite/sand). Pore water concentrations in the different sites were studied using diffusive gradient in thin film (DGT) probes. All capping amendments showed reduction in the pore water concentration of the different heavy metals with top 5 cm showing %reduction greater than 90% for some heavy metals. The relative maxima for the different metals were found to be translated to lower depths with addition of the caps. For two-layered cap with AC, order of placement should be considered since AC can easily be displaced due to its relatively low density. Investigation of methylmercury (MeHg) in the site showed that MeHg and %MeHg in pore water corresponds well with maxima for sulfide, Fe and Mn suggesting mercury methylation as probably coupled with sulfate, Fe and Mn reduction in sediments. Our results showed that thin-layer capping of active sorbents AC and zeolite, in combination with passive sand caps, are potential remediation strategy for sediments contaminated with heavy metals.

• Journal of Environmental Science International
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• v.14 no.10
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• pp.955-963
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• 2005

From sludge of S municipal wastewater treatment plant in Busan, Korea, we isolated the denitrifier DN-9 which showed the ability of denitrification under aerobic conditionby the color change and gas formation in liquid culture with Giltay medium. The isolated strain was identified as Pseudomonas sp. DN-9 on the basis of the morphological, physiological, biochemical and nucleotide sequence analysis of l6S rRNA. The isolated strain, Pseudomonas sp. DN-9, has cytochrome $cd_1$, nirS of nitrite reductase. By the co-existance of additional ammonium and nitrate ion, the strain was not affected largely on growth in SL series broth. It seemed the result of denitrification. Although Pseudomonas sp. DN-9 has a good nitrate reduction activity under aerobic condition, the activity is less than Pseudomonas stutzeri in same cultivation condition. However, Escherichia coli had little the activity of aerobic denitrification and Pseudomonas putida showed lower activity of aerobic denitrification than Pseudomonas sp. DN-9 and Pseudomonas stutzeri in this study.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.7
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• pp.980-985
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• 2010

The objective of this study was to isolate and identify anti-inflammatory chemicals in Hippophae rhamnoides L. which was grown in Chuncheon, Korea. Treatment of ethanol extracts from stems, leaves, roots, and fruits to RAW 264.7 cells reduced amounts of nitrite by 56.0, 31.9, 49.1, and 18.9% respectively, compared to only lipopolysaccharide (LPS) treatment which is well-known as a inflammation-inducing agent. The stems were extracted with hexane, dichloromethane, ethyl acetate, butanol, and water and their nitrite contents in RAW 264.7 cells were measured. The dichloromethane extracts showed the highest inflammatory activity, exhibiting 80% reduction of the nitrite content at 1 mg/mL treatment. Activity-directed fractionation of dichloromethane extracts led to the identification of $\beta$-sitosterol as the anti-inflammatory chemical. 0.1 mg/mL treatment of $\beta$-sitosterol inhibited strongly the production of nitrite by 65%, compared to only LPS treatment. These results suggest that stem of H. rhamnoides L. may be useful for inflammation treatment.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.1
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• pp.105-110
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• 1985

A incubation study was conducted to find out the effects of rice straw and gypsum as soil ameriolite on urease, nitrate and nitrite reductase activities in newly reclaimed saline sandy soil. The results obtained were summarized as follows: 1. Very low urease activities were observed in saline soil if contrast to high productive paddy soil. Urease activities were lower at 5 days than that of 25 and 50 days after incubation. Remarkably high urease activities were obtained by the application of rice straw and gypsum. 2. Comparing with NPK treatment, application of rice straw and gypsum were enhanced the activities of nitrate and nitraite reductase. 3. Positive correlation (r=0.5501 p=0.05) was obtained between urease activities and ammonium nitrogen concentration in soil. 4. Cyclic oxidation and reduction of nitrate and nitrite in soil were obtained in terms of first order microbial kinetics reaction in case of application of rice straw and gypsum, respectively. 5. Positive correlation (r=0.6296 p=0.05) was obtained between the activitie of nitrite reductase and nitrate reductase in soil.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.4
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• pp.343-351
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• 2001

This study was undertaken to investigate the mechanism of lipopolysaccharide (LPS) and nitric oxide (NO) as a regulator of vascular smooth muscle cell (VSMC) proliferation. VSMC was primarily cultured from rat aorta and confirmed by the immunocytochemistry with anti-smooth muscle myosin antibody. The number of viable VSMCs were counted, and lactate dehydrogenase (LDH) activity was measured to assess the degree of cell death. Concentrations of nitrite in the culture medium were measured as an indicator of NO production. LPS was introduced into the medium to induce the inducible nitric oxide synthase (iNOS) in VSMC, and Western blot for iNOS protein and RT-PCR for iNOS mRNA were performed to confirm the presence of iNOS. Inhibitors of iNOS and soluble guanylate cyclase (sGC), sodium nitroprusside (SNP) and L-arginine were employed to observe the action of LPS on the iNOS-NO-cGMP signalling pathway. LPS and SNP decreased number of VSMCs and increased the nitrite concentration in the culture medium, but there was no significant change in LDH activity. A cell permeable cGMP derivative, 8-Bromo-cGMP, decreased the number of VSMCs with no significant change in LDH activity. L-arginine, an NO substrate, alone tended to reduce cell count without affecting nitrite concentration or LDH level. Aminoguanidine, an iNOS specific inhibitor, inhibited LPS-induced reduction of cell numbers and reduced the nitrite concentration in the culture medium. LY 83583, a guanylate cyclase inhibitor, suppressed the inhibitory actions of LPS and SNP on VSMC proliferation. LPS increased amounts of iNOS protein and iNOS mRNA in a concentration-dependent manner. These results suggest that LPS inhibits the VSMC proliferation via production of NO by inducing iNOS gene expression. The cGMP which is produced by subsequent activation of guanylate cyclase would be a major mediator in the inhibitory action of iNOS-NO signalling on VSMC proliferation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.1
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• pp.201-206
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• 2004

This study was carried out to investigate the effect of addition mugwort podwer and carcass grade on the shelf life of pork ham. Pork ham was prepared by four type such as grade B pork ham ( $B_{o}$ ), grade B pork ham containing mugwort powder ( $B_{+}$), grade E pork ham ( $E_{o}$ ) and grade E pork ham containing mugwort powder ( $E_{+}$). The surface color, pH, residual nitrite, VBN (volatile basic nitrogen), TBARS (2-thiobarbituric acid reactive substances) and total bacterial counts of the samples were determined during storage for 8 weeks at 4$^{\circ}C$. The $L^{*}$ value of $B_{o}$ and $B_{+}$ ham showed higher at the latter period of 8 weeks, that of $E_{o}$ ham was the highest on at the storage of 2nd week and that of $E_{+}$ ham was not different during 8 weeks storage. The $L^{*}$ value of B grade ham was higher than that of E grade ham and the $a^{*}$ value of E grade ham was higher than that of B grade ham. The pH of all ham decreased during storage, but increased from 8 weeks. The residual nitrite of all ham highly decreased until storage for 2 weeks, the addition of mugwort powder was affected in the reduction of residual nitrite of pork ham. The VBN contents were 6.90∼7.90 mg% in the early period of storage, was 14.07∼14.83 mg% on the storage of 8th week. The TBARS of pork ham were increased gradually during storage and pork ham containing mugwort powder showed lower value than pork ham non added mugwort powder during 4th and 6th weeks storage. The total bacterial counts of pork ham were increased gradually during storage and the addition of mugwort powder was not effective.ive.ctive.ive.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.2
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• pp.237-243
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• 2017

To investigate the effects of lactic acid bacteria (LAB), Lactobacillus sakei, Lactobacillus curvatus, and Lactobacillus brevis, commonly found in kimchi, on N-nitrosodimethylamine (NDMA) and its precursors such as nitrite, dimethylamine (DMA), nitrate, and biogenic amines, Baechu (Chinese cabbage) kimchi prepared with and without LAB and $NaNO_2$ was periodically monitored for 20 days to analyze concentrations of NDMA and its precursors. Control was amine and nitrite-rich kimchi. NDMA and its precursors were analyzed to determine differences in concentrations between LAB-fortified kimchi and the control. The amounts of NDMA, nitrite, DMA, and nitrate remaining in LAB-fortified kimchi were significantly reduced compared with those of control kimchi. In addition, biogenic amines were significantly lower in kimchi prepared with L. sakei, L. curvatus, and L. brevis. These results suggest that addition of LAB to the kimchi preparation would be a promising solution for production of NDMA-reduced kimchi.