• Journal of the Korean Society of Food Science and Nutrition
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• v.14 no.4
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• pp.329-338
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• 1985

This study was undertaken in order to research formation of nitrosamine and its related compounds by salt concentration and nitrate content during Korean native soysauce fermentation. The results from measuring the changes of nitrite and dimethylamine content can be summerized as follows. As the nitrate content in used water was getting higher and the salt concentration was getting lower, the soysauce fermentation was abnormal. As the salt concentration was getting higher, the reduction of nitrate and formation of nitrite were delayed. But whether the nitrate content in used water was higher or not, the nitrite was continuously remained. An addition of ascorbic acid restrained the reduction of nitrate, and simultaneously, it could eliminate the nitrite effectively. As the nitrate content in used water, was getting higher, the content of dimethylamine was getting lower. Nitrosodimethylamine was detected from 0 to 261.34 ppb.

• Journal of Microbiology and Biotechnology
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• v.17 no.2
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• pp.218-225
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• 2007

A lactic acid bacterium capable of anaerobic respiration was isolated from soil with ferric iron-containing glucose basal medium and identified as L. garvieae by using 16S rDNA sequence homology. The isolate reduced ferric iron, nitrate, and fumarate to ferrous iron, nitrite, and succinate, respectively, under anaerobic $N_2$ atmosphere. Growth of the isolate was increased about 30-39% in glucose basal medium containing nitrate and fumarate, but not in the medium containing ferric iron. Specifically, metabolic reduction of nitrate and fumarate is thought to be controlled by the specific genes fnr, encoding FNR-like protein, and nir, regulating fumarate-nitrate reductase. Reduction activity of ferric iron by the isolate was estimated physiologically, enzymologically, and electrochemically. The results obtained led us to propose that the isolate metabolized nitrate and fumarate as an electron acceptor and has specific enzymes capable of reducing ferric iron in coupling with anaerobic respiration.

• Membrane and Water Treatment
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• v.9 no.3
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• pp.189-194
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• 2018

Electrochemical reduction of nitrate was studied using Zn, Cu and (Ir+Ru)-Ti cathodes and Pt/Ti anode in a cell divided by an ion exchange membrane. During electrolysis, effects of the different cathode types on operating parameters (i.e., voltage, temperature and pH), nitrate removal efficiency and by-products (i.e., nitrite and ammonia) formation were investigated. Ammonia oxidation rate in the presence of NaCl was also determined using the different ratios of hypochlorous acid to ammonia. The operating parameter values were similar for all types of cathode materials and were maintained relatively constant. Nitrate was well reduced and converted mostly to ammonia using Zn and Cu cathodes. Ammonia, produced as a by-product of nitrate reduction, was oxidized in the presence of NaCl in the electrochemical process and the oxidation performance was enhanced upon increasing the hypochlorous acid-to-ammonia ratio to 1.09:1. Zn and Cu cathodes promoted the nitrate reduction to ammonia and the produced ammonia was finally removed from solution by reacting with hypochlorite ions. Using Zn or Cu cathodes, instead of noble metal cathodes, in the electrochemical process can be an alternative technology for nitrate-containing wastewater treatment.

• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.630-638
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• 2019

Nitrous oxide (N₂O) is a greenhouse gas with a global warming potential 310 times higher than that of carbon dioxide. In this study, an N₂O-reducing consortium was obtained by enrichment culture using advanced treatment sludge as the inoculum. The dominant bacteria in the consortium were Sulfurovum (17.95%), Geobacter (14.63%), Rectinema (11.45%), and Chlorobium (8.24%). The consortium displayed optimal N₂O reducing activity when acetate was supplied as the carbon source at a carbon/nitrogen ratio (mol·mol^-1) of 6.3. The N₂O reduction rate increased with increasing N₂O concentration at less than 3,000 ppm. Kinetic analysis revealed that the maximum N₂O reduction rate of the consortium was 163.9 ㎍-N·g-VSS^-1·h^-1. Genes present in the consortium included nosZ (reduction of nitrous oxide to N₂), narG (reduction of nitrate to nitrite), nirK (reduction of nitrite to nitric oxide), and norB (reduction of nitric oxide to nitrous oxide). These results indicate that the N₂O-reducing consortium is a promising bioresource that can be used in denitrification and N₂O mitigation.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.5
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• pp.228-235
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• 2016

Nitrite accumulation is essential for constructing an anammox process. As the pH in the reactor exerts a complicated and strong influence on the reaction rate, we investigated its effects upon treatment of an ammonic wastewater (2,000 mgN/L) through modeling and experiment. The modeling results indicated that the reaction stability is strongly affected by pH, which results in a severe reduction of the 'stable region' of operation under alkaline environments. On a coordinate of the total ammonia nitrogen (TAN) concentration vs. pH, the maximal stable reaction rates and the maximal nitrite accumulation potentials could be found on the 'stability ridge' that separates the stable region from the unstable region. We achieved a stable and high ammonia oxidation rate (${\sim}6kgN/m^3-d$) with a nitrite accumulation ratio of ~99% when operated near the 'stability ridge'. The optimum pH that can be observed in experiments varies with the TAN concentrations utilized, although the intrinsic optimum pH is fixed. The direction of change is that the optimum operational pH falls as the TAN concentration increases, which is in excellent accordance with the observations in the literature. The optimum operational pH for 95% nitritation was predicted to be ~8.0, whereas it was ~7.2 for 55% partial nitritation to produce an anammox feed in our experimental conditions.

• Korean Journal of Food Science and Technology
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• v.11 no.3
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• pp.147-152
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• 1979

Nitrite, one of the precursors of dimethylnitrosamine, distributes widely in natural foods and is also used as a color fixing agent in meat products. This experiment was carried out to determine the contents of nitrite and nitrate of Korean foods and suman saliva. Nitrite content was measured by use of the diazotization-coupling reaction, while cadmium reduction method by use of metallic cadmium was applied to determine nitrate. The objects are about 150 of female students who are $19{\sim}22$ years old ands standard analytical values of nitrate contents of $10{\sim}20$ samples produced in various places. The results showed that contents of nitrite and nitrate of Korean foods and saliva were relatively high levels.

• Applied Biological Chemistry
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• v.43 no.2
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• pp.110-115
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• 2000

This study was carried out to investigate the effect of extracts from garlic on the formation of nitrosamine, nitrosomorphorine, the nitrite scavenging ability and the antioxidant activity. The extracts from garlic made the nitrite scavenging ability higher at low pH than at high pH. Especially ethanol extracts from garlic resulted in 89.6% of nitrite scavenging ability at pH 1.2. They were also more effective in the electron donating and antioxidant abilities than water extracts in expressing as the reduction of ${\alpha},{\alpha}-diphenyl-{\beta}-picrylhydrazyl$(DPPH) and peroxide value(POV), respectively. Inhibitory effect of nitrosamine formation by ethanol extract from garlic was excellently more than 80% at pH 1.2 and 3.0, but only 29.9% at pH 6.0. This meant that the inhibition of nitrosamine formation is pH dependent.

• The Korean Journal of Food And Nutrition
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• v.20 no.2
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• pp.114-119
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• 2007

Our research objective was to examine the in vitro biological activity of deer antler(Nogyong in Korean) extract, including the antioxidative, nitrite scavenging, and tyrosinase inhibitory effects, as well as the antithrombotic, and angiotensin I converting enzyme(ACE) inhibitory activities. The carbohydrate, protein, fat, and mineral contents of the deer antler were 7.6%, 65.3%, 3.2% and 23.9%, respectively. The electron donating ability(EDA) by the reduction of 2,2'-diphenyl-1-picrylhydrazyl(DPPH) was 67.1%, and the inhibition rate of lipid peroxidation by the thiocyanate method using linoleic acid was 92.1% in 100 mg/ml of extract. The nitrite scavenging effects were pH dependent, and were highest at pH 1.2 and lowest at pH 6.0. The sample inhibition rate against tyrosinase was above 64.0%. The platelet aggregation induced by ADP(adenosine-5'diphosphate) was inhibited up to 51.7%, and the inhibitory effect was dependent on the sample concentration. Lastly, the inhibition rate of ACE was 47.5% in 100 mg/ml of deer antler extract.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.303-308
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• 1998

A bacterial strain which utilizes phenol under denitrifying condition was isolated from the industrial waste water collected from the Chong-ju Industrial Complex. The strain was identified as Pseudomonas species from the morphological, physiological, and biochemical characteristics and designated as HL100. The strain can utilize phenol as the sole source of carbon and energy when nitrate is provided as the terminal electron acceptor. The isolated strain completely degraded 3 mM of phenol within 110 hour with concomitant reduction of nitrate to nitrite. The observed maximum doubling time was 20 hours. Under appropriate condition, complete reduction of nitrate to atmospheric N$_2$ was observed indicating that the isolated strain could perform complete steps of denitrification. The strain showed optimal growth at pH 7.0 and temperature of 37$^{\circ}C$ under denitrifying phenol-degrading condition. The strain can also utilize toluene as the sole carbon and energy source under the same growth condition. However, no growth was detected on xylene and benzene.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4570-4575
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• 2023

Noise and Radio-frequency interference or RFI causes a significant restriction on the Free induction Decay or FID signal detection of the Nuclear Quadrupole Resonance procedure. Therefore, using this method in non-isolated environments such as industry and ports requires extraordinary measures. For this purpose, noise reduction algorithms and increasing signal-to-noise-and-interference ratio or SNIR have been used. In this research, sodium nitrite has been used as a sample and algorithms have been tested in a non-isolated environment. The resonant frequencies for the 150 g of test sample were measured at 303 K at about 1 MHz and 3.4 MHz. The main novelty in this study was, (1) using two types of antennas in the receiver to improve adaptive noise and interference cancellation, (2) using a separate helical antenna in the transmitter to eliminate the duplexer, (3) estimating the noise before sending the pulse to calculate the weighting factors and reduce the noise by adaptive noise cancellation, (3) reject the interference by blanking algorithm, (4) pulse integration in the frequency domain to increase the SNR, and (5) increasing the detection speed by new pulse integration technique. By interference rejection and noise cancellation, the SNIR is improved to 9.24 dB at 1 MHz and to 7.28 dB at 3.4 MHz, and by pulse integration 44.8 dB FID signal amplification is achieved, and the FID signals are detected at 1.057 MHz and 3.402 MHz at room temperature.