• 대한환경공학회지
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• 제28권10호
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• pp.1024-1030
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• 2006

Genus Nitrospira와 Nitrobacter는 폐수 질산화 시스템의 대표적인 아질산 산화균으로 알려져 있다. Genus Nitrospira는 아질산 농도가 매우 낮은 조건에서도 이를 효율적으로 활용하는 K-strategists로 알려져 있는 반면에 Nitrobacter 종은 기질소비와 성장이 빠른 r-strategists로 알려져 왔다. 또한 유기물이나 용존산소도 아질산 산화균의 분포에 영향을 주는 것으로 알려져 있다. 본 연구에서는 아질산과 유기물, 용존산소가 복합적으로 작용하는 질산화 시스템에서 아질산 산화균의 분포와 경쟁에 어떻게 영향을 받는지를 검토하였다. 이를 위하여 실험실 규모의 질산화 생물반응기와 질산화-탈질을 수행하는 $A_2O$ 계열의 실제 폐수처리장에서 여러 항목과 두 종류의 아질산 산화균 분포를 측정, 비교하였다. 그 결과 아질산 농도는 평균 5 mg-N/L로 유지되며, 호기조건에서 유기물이 매우 낮게 유지되는 실험실 질산화 생물반응기는 Nitrobacter가, 호기-무산소 조건에서 질산화-탈질이 일어나고 아질산이 거의 없는 상태이며 유기물이 비교적 높게 유지되는 $A_2O$ 폐수처리장은 Nitrospira가 우점종으로 분포하였다. 이것은 여러 인자가 복합적으로 작용하는 상태에서는 아질산 산화균의 분포가 유기물과 용존산소 보다는 아질산 농도가 가장 중요한 인자임을 보여주며 기질 친화도가 낮지만 반응속도가 빠른 Nitrobacter가 r-strategist, genus Nitrospira는 기질친화도가 높은 K-strategist인 특성을 보임을 확인하였다.

• Preventive Nutrition and Food Science
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• 제6권3호
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• pp.142-146
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• 2001

This study was performed to investigate chemical and functional properties of Glechoma hederacea leaves in respect to its potential use as food material or as a medicinal herb. The chemical compositions on a dry harris were 20.38% in protein, 3.96% in fat, 59.58% in carbohydrate, 15.78% in ash, 5.36% in reducing sugar, 14.11% in total sugar and 0.26% in polyphenol, respectively. The free sugars were mainly comprised of glucose, fructose and sucrose. In fatty acids compositiosn, linolenic acid showed the highest concentration at 45%, while the ratios of saturated to unsaturated fatty acids were 1 : 1.91. Seventeen kinds of total amino acids were determined, with the highest concentration (2,465.71 mg%) of glutamic acid. Among the free amino acids, praline showed the highest concentration (260.09 mg%), followed by glutamine, $\alpha$ -amino adipic acid, glutamic acid and valine. The contents of major minerals were 647.32 mg% in Na, 597.53 mg% in K and 239.75 mg% in Ca. The antioxidative activity of 10% water extract was similar to that of 50 ppm tocopherol. The nitrite scavenging ability reached the highest bevel at pH 1.2 and the lowest at pH 6.0.

• 동아시아식생활학회지
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• 제21권5호
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• pp.677-682
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• 2011

This study explores the antioxidant activities of solvent extracts from Rhus verniciflua, and the results were as follows. Total phenolic compound and flavonoid contents of Rhus verniciflua were $4.32{\pm}0.17$ mg/100 g and $0.16{\pm}0.02$ mg/100 g, respectively. Electron-donating abilities of solvent extracts from Rhus verniciflua proportionally increased with concentration, and ethyl acetate extract ($95.4{\pm}0.4%$) showed higher activity than that of BHT ($93.3{\pm}1.7%$) at a concentration of 1,000 ${\mu}L$/mL. Reducing power of the solvent extracts from Rhus verniciflua was the highest in ethyl acetate extract ($2.45{\pm}0.03$) at a concentration of 1,000 ${\mu}L$/mL. Nitrite scavenging ability of the solvent extracts from Rhus verniciflua (pH 1.2, 1,000 ${\mu}L$/mL) was the highest in ethyl acetate extract ($95.5{\pm}0.7%$). Therefore, ethyl acetate extract from Rhus verniciflua has similar antioxidant activity as that of BHT.

• Corrosion Science and Technology
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• 제16권3호
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• pp.91-99
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• 2017

The objective of this work was to develop efficient synergistic inhibitor combinations comprising sodium nitrite ($NaNO_2$) and an inhibitor-blend code named (SN-50), keeping in view of their application in industrial cooling water systems. The electrochemical characteristics of the carbon steel working electrode in simulated cooling water (SCW), without and with the addition of different combinations of the inhibitors, were investigated using electrochemical impedance spectroscopy (EIS), open circuit potential (OCP). The electrode surface changes were followed by visual characterization methods. It was demonstrated in this study that all the combinations of the inhibitors exhibited synergistic benefit and higher inhibition efficiencies than did either of the individual inhibitors. The addition of SN-50 inhibitor to the SCW shifted the OCP to more anodic values and increased the polarization resistance ($R_p$) values of carbon steel at all applied concentrations. The higher the applied sodium nitrite concentration (in the protection concentration range), the higher the obtained $R_p$ values and the inhibition efficiency improved by increasing the inhibitor concentration.

• Food Science and Biotechnology
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• 제15권3호
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• pp.351-356
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• 2006

In this study, we investigated the effect of adding a 1, 3, or 5% solution of germinated brown rice concentrate (GBRC) to fermented kimchi. During fermentation, the concentration of free amino acids and essential amino acids increased with increasing concentrations of GBRC. In particular, higher levels of free amino acids were associated with a sweet taste compared with controls. The ${\gamma}$-aminobutyric acid (GABA) content of kimchi containing the 5% GBRC solution was 3 times higher than that of controls. The total phenolic compound content (130 mg%) did not change significantly in the control group, but increased in 10 mg% increments as the GBRC concentration rose from 1 to 3 to 5%. 2,2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging activity and superoxide radical scavenging activity also increased with the GBRC concentration, with maximum activity during the ripe stage with GBRC measured at 79 to 82% compared with controls (30 to 71 %). The nitrite scavenging activity was 10% higher with GBRC compared with controls and was highest when the pH was 1.2. These results showed that the addition of GBRC is effective in improving the function of kimchi.

• Bulletin of the Korean Chemical Society
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• 제27권6호
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• pp.875-880
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• 2006

A new, simple and fast flow injection analysis (FIA) method has been developed for the indirect determination of nitrite. The proposed indirect automatic method is based on the oxidation of nitrite to nitrate using a lead(IV) dioxide oxidant microcolumn where the flow of the sample through the microcolumn reduces the $PbO_2$ solid phase reagent to Pb(II), which is measured by flame atomic absorption spectrometry. The absorbance of Pb(II) are proportional to the concentration of nitrite in the samples. The calibration curve was linear up to 30 mg $L ^{-1}$, with a detection limit of 0.11 mg $L ^{-1}$ for a 400 mL injected sample volume and a sampling rate of about 80 $h ^{-1}$. The results exhibit no interference from the presence of large amounts of ions. The developed procedure was found to be suitable for the determination of nitrite in foodstuffs and wastewaters. A relative standard deviation better than 0.9% was obtained in a repeatability study. The reliability of the method was established by parallel determination against the standard method.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.457-460
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• 2000

Biofilm airlift 반응기를 이용한 선택적 질산화는 air가 2.5 L/min, $NH_4\;^+-N$ load가 $2.5\;kg-N/m^3/d$에서 약 90% 이상의 질소 제거율과 75-90%의 아질산성 질소의 축적이 일어났다. nitrite oxidizer가 낮은 DO의 영향으로 activity가 저해를 받아서 nitrite를 산화시키지 못하여 축적을 일으킨 것으로 보인다. 반응기 내부의 미생물의 양이 가장 많은 기간에 질소 제거율이 저하하고 nitrite ratio가 약간 감소됨을 보였다. 이는 많은 미생물의 양으로 용존산소가 감소되었기 때문이다. 미생물의 양에 따른 질소 부하의 증거로 F/M 비를 맞추어 그에 따른 질산화를 관찰하는 연구를 할 수 있을 것 같다.

• 한국물환경학회지
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• 제22권4호
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• pp.711-719
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• 2006

The effluent from anaerobic digestion process of slurry-type piggery waste has a characteristic of very low C/N ratio. Because of high nitrogen content, it is necessary to evaluate nitrogen removal alternative rather than conventional nitrification-denitrification scheme. In this study, two parallel treatment schemes of SBR-like partial nitritation reactor coupled with anaerobic ammonium oxidation (ANAMMOX) reactor, and a nitritation reactor followed by nitrite denitrification process were evaluated with a slurry-type piggery waste. The feed to reactors adjusted with various $NH_4-N$ and organics concentration. The nitrite accumulation was successfully accomplished at the loading rate of about $1.0kgNH_4-N/m^3-day$. The $NO_2-N/NH_4-N$ ratio 1~2.6 in nitritated effluent that operated at HRT of 1 day indicated that SBR-like partial nitritation was applicable to ANAMMOX operation. Meanwhile, the nitrite accumulation of 87% was achieved at SBR operated with HRT of 3 days and $0.4mgO_2/L$ for denitritation. Experimental results further suggested that HRT (SRT) and free ammonia(FA) rather than DO are an effective control parameter for nitrite accumulation in piggery waste.

• 한국물환경학회지
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• 제30권2호
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• pp.220-225
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• 2014

A sequencing batch reactor (SBR) was operated to obtain thiosulfate-utilizing denitrifier cultivated with two types of electron accepter (nitrate and nitrite). Using the microbial biomass obtained from the SBR, batch tests were conducted with different nitrite concentrations (50 and 100 mg-N/L) at pH 7.0, 7.5 and 7.9 to see how free nitrous acid (FNA) negatively works on the thiosulfate-utilizing denitrification of nitrate. The specific denitrification rate (SDR) of nitrate was significantly influenced by pH and FNA. The presence of nitrite caused a remarked decrease of the SDR under low pH conditions, because of the microbiological inhibitory effect of FNA. The minimum SDR was observed when initial nitrite concentration was 100 mg-N/L at pH 7.0. Moreover. the SDR was influenced by the type of electron acceptor used during the SBR operation. Thiosulfate-utilizing denitrifier cultivated with nitrite showed smaller SDR on the thiosulfate-utilizing denitrification of nitrate than those cultivated with nitrate.

• Journal of Applied Biological Chemistry
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• 제56권4호
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• pp.205-211
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• 2013

Nitrate is a naturally occurring compound in plant and can be converted to nitrite in the nitrogen cycle and vice versa. Therefore, it is easy to find nitrate in plants including vegetables. Especially, it is known that high levels of nitrate found in leafy vegetables. Nitrate itself is relatively non-toxic but its metabolites and reaction products such as nitrite, nitric oxide and N-nitroso compounds, may produce adverse health effects such as methaemoglobinaemia and carcinogenesis. To execute the risk assessment of dietary nitrate and nitrite for the intake of vegetables, it is investigated that the levels of nitrate and nitrite in 23 vegetables (798 samples). The range of concentration were 0-6,719mg/kg for nitrate and 0-1,635mg/kg for nitrite, respectively. The Estimated daily intakes (EDI) were 0.85-1.38 mg/kg body weight/day for nitrate and 0.02-0.03 mg/kg body weight/day for nitrite by ages. We conclude that there are no health concerns for eating various vegetables since the EDI were below the Tolerable Daily Intake (3.7 mg/kg body weight/day for nitrate, 0.06 mg/kg body weight/day for nitrite) level established by WHO.