• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.155-157
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• 1998

Dinitramide salts may be useful as effective solid oxidizers because of higher oxygen content than nitrate salts. 3-Nitramino-propanoate was given by base treatement in the retro-Michael reaction of N-nitro-4-azaheptanedioate, which was prepared by nitration of 4-azaheptanedioate using $HNO_3$-TFAA(trifiluoroacetic anhydride)-$Br_2$. The nitramino compound was treated wile $NO_2BF_4$ to give dinitramino compound which was subsequently reacted with bases to give dinitramide salts.

• Korean Journal of Materials Research
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• v.8 no.5
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• pp.394-398
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• 1998

We have studied the effect of Ag additions on the microstructure and the related mechanical and supercon¬ducting properties of $ YBa_{2}$$Cu_{3}$$O_{7-\delta}$ (YBCO) superconductors. A 5-15 vol.% of Ag was added to YBCO in the forms of Ag and $AgNO_{3}$, powder and the resultant microstructural evolution was evaluated. It was observed that the strength and fracture toughness of YBCO increased with increasing Ag content. These improvements in strength and fracture toughness are believed to be due to the strengthening mechanisms caused by the presence of Ag. In addition, YBCO-Ag composite superconductors showed higher values of strength and fracture toughness when Ag was added in the form of AgNO, than those of which was added Ag. The higher mechanical properties of YBCO- Ag resulting from $AgNO_{3}$, addition are probably due to the microstructure of more finely and uniformly distributed Ag particles. The addition of Ag also showed slightly improved critical current density of YBCO superconductors.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.4
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• pp.606-613
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• 1997

The changes of contents in trimethylamine oxide nitrogen(TMAO-N), trimethylamine nitrogen(TMA-N), dimethylamine nitrogen(DMA-N), nitrite nitrogen(nitrite-N), nitrate nitrogen(nitrate-N) and the effect on the formation of N-nitrosamine(NA) during fermentation were investigated with salted anchovy added different amounts of sodium nitrite, sodium nitrate and ascorbic acid, respectively. When the sodium nitrite was added in salted anchovy, the contents of nitrite-N was decreased during fermentation . Whereas the formation of N-nitrosodimethylamine(NDMA ) was increased . Contents of TMAO-N was decreased, while TMA-N and DMA-N were increased during fermentation in all samples. Addition of ascorbic acid inhibited the formation of NDMA significantly. The formation of NDMA was inhibited by 81.3% at the concentration of 130mM as compared with non-added the control group. The aqueous model system was used for the evaluation of ascorbic acid(inhibitor) or thiocyanate (promoter) on the formation of NDMA using salt-fermented anchovy added with sodium nitrite. The optimum pH on the formation of NDMA was shown to be 3.8, and ascorbic acid inhibited the formation of NDMA whereas thiocyanate promoted. NDMA was not detected in the salt-fermented anchovy (control sample). However it is a possibility to form carcinogenic NDMA in stomach if both saltfer-mented anchovy and the materials contained abundant nitrite or nitrate were took in.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.4
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• pp.614-619
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• 1997

To examine effects of drying methods on the formation of N-nitrosamine(NA) in squid during its drying. Three different types of dried products, which were made by sun, hot-air and traditional drying of squid after removal of intestines, were utilized. NA was analyzed by a gas chromatography-thermal energy analyzer. The contents of nitrate and nitrite nitrogen in dried products were in the range of 0 to 5.2mg/kg and 0 to 2.7mg/kg, respectively. The contents of TMAO and betain nitrogen in squid during its drying decreased, while those of TMA and DMA nitrogen increased. The contents in dried products were 27.8~29.2mg% and 10.4~12.3mg/kg, respectively. N-Nitrosodimethylamine (NDMA) was only detected in squid during its drying, recovery from raw sample and its dried pro- ducts spiked with 10$\mu\textrm{g}$/kg for NDPA was 81.0~ 100.0%. NDMA in raw samples was found to be below 0.05$\mu\textrm{g}$/kg. The levels of NDMA in squid increased remarkably during its drying and those in dried products were ranged from 2.7 to 42.7$\mu\textrm{g}$/kg. The effects of drying methods in squid were found to be quite different. the levels of NDMA in traditionally dried products were 11~16 and 3~4 times higher than those in sun dried and hot-air dried products, respectively It is believed that high levels of NDMA were detected in traditionally dried products because NDMA was formed from reaction between various amines and nitrogen oxide produced by combustion of briquet during drying of squid.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.3
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• pp.291-306
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• 1984

The possibility of formation of carcinogenic N-nitrosamines such as nitrosodimethylamine(NDMA), nitrosodiethylamine (NDEA) and nitrosopyrolidine (NPYR) during the fermentation of Kimchi was investigated. Three different types of Kimchi, formulated with chinese cabbage, red pepper powder and garlic, with or without one of both fermented shrimp and anchovy juice, were cured for 75 days at $5^{\circ}C$. The changes in contents of nitrates, nitrites, pH, ascorbic acid, secondary amines, trimethyl-aminoxide (TMAO), trimethylamine (TMA) and NDMA were analyzed periodically during the fermentation. TMAO, TMA. DMA, nitrate, nitrite and ascorbic acid were analyzed by colorimetric methods, and NDMA, NPYR and NDEA were determined by the method of GLC-TEA. Although the total secondary amines markedly increased, no significant changes in the levels of TMAO and TMA were observed during the fermentation Kimchi added with fermented shrimp or anchovy juice. The predominating component of secondary amines was confirmed to be dimethylamine by means of nitrosating technique coupled with gas chromatography. No appreciable increase in the level of nitrites was appeared although nitrate level in the Kimchi apparently decreased. Non detectable or trace level of nitrosamine formation was detected whereas the nitrates fairly decreased during the fermentation of Kimchi. This could be explained by the fact that the lack of nitrites was resulted in the system due to rapid consumption of nitrites formed from nitrates by the reactions with ascorbic acid and amino acids which have been known as inhibitors of nitrosation reaction.

• Journal of Nutrition and Health
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• v.15 no.1
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• pp.39-46
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• 1982

Nitrate accumulated in vegetables can, via $NO_2$ during storage and after their ingestion, cause the formation of methemoglobin and many of which are carcinogenic in human body. Especially such vegetables with the highest consumption in Korea as chinese cabbage and raddish frequently showed that high contents of nitrate and nitrite could accumulate. Therefore, pH and the content of nitrate and nitrite of Korean pickles made of upper vegetables, viz, Baiechu Kimchi, Yulmookimchi and Kakdooki were estimated during storage at the conditions of $5^{\circ}C$ and $25^{\circ}C Storage at $25^{\circ}C$ generally led to the more rapidly than that at $5^{\circ}C$. But changes of nitrite level showed very low variation in all tested Kimchi.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.969-972
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• 1999

Nitrate is taken up from the soil by plants for protein synthesis and present in vegetables as a natural component and/or contaminant. The objective of this study was to estimate nitrate(NO3-) contents of some vegetables(Chinese cabbage, radish, lettuce, spinach) which were produced in Korea and to provide a scientific basis for the evaluation of risk to public health arising from dietary exposure to nitrate. A total of 400 samples were analysed for nitrate contents using our ion chromatography. From the results, in general, nitrate levels in vegetables produced by 2 harvest seasons were not different. The minimum, maximum and mean values of nitrate were 311, 5522 and 2788 for spinach; 542, 4484 and 2287 for lettuce; 273, 4151 and 1551 for radish; 362, 3015 and 1498(mg/kg) for Chinese cabbage. Nitrate contents of vegetables grown in Korea were similar to those of vegetables grown in other countries.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.05a
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• pp.168-172
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• 2005

초산, 질산 및 인산이 함유된 폐혼산에서 초산과 질산을 1차 분리하고 남은 조인산으로부터 정제인산으로 회수한 후 에칭액의 원료로 재활용하기 위하여 용매 추출 기술을 검토하였다. 알루미늄(Al) 및 몰리브덴(Mo) 불순물이 함유된 조인산을 인산염 추출제를 이용하여 인산을 추출한 후 세정공정과 탈거공정을 거쳐 알루미늄과 몰필브덴을 분리하기 위한 최적 분리조건을 도출하고자 하였다. 실험 결과 추출공정과 세정공정, 그리고 탈거 공정을 통하여 알루미늄 및 몰리브덴의 함량을 1ppm이하로 분리 제거하여 정제 인산으로 회수가 가능하였다.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.1
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• pp.9-15
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• 1998

A survey was conducted to investigate the chemical properties of soils such as pH, electrical conductivity, total organic matter content, soluble nitrate, available phosphate and major exchangeable canons, in plastic film houses at 513 sites. All the parameters surveyed in the plastic film house were much higher than those of open field soils. Particularly conspicuous was the accumulation of available P, exchangeable K and the occurrence of nitrate at relatively high concentration in both top soil(0-20 cm) and sub-soil(20-40 cm). In 70-80% of cases, the contents of available P and exchangeable K in top soils, were found to be higher than optimum levels. There was positive linear correlation between the content of exchangeable rations, and nitrate and EC of soils. The correlation coefficient was greater in the order of nitrate-EC > Mg-nitrate > K-nitrate > Ca-nitrate. The successive cultivation of horticultural crops in the plastic houses tended result in the accumulation of available P, exchangeable K and total organic matter in the soil.

• Korean Journal of Environmental Agriculture
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• v.37 no.1
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• pp.28-33
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• 2018

BACKGROUND: In this study, we evaluated the effects of soil incorporation of hairy vetch (HV) or ryeas a green manure on the growth and yields of watermelon and soil nitrate nitrogen in a green house.. METHODS AND RESULTS: HV and rye were cultivated for 151 days after sowing on October 30th and incorporated into soil before transplanting watermelon. The amount of N added by soil incorporation of HV and rye were 79 kg/ha and 88 kg/ha, respectively. Five different N treatments for each of HV and rye were included as follows: green manure, green manure with urea at 25%, 50%or 75%, and 100% ureafor the N recommendation rate. The growth and fruit yield of watermelon were not different among the treatments of both HV and rye. Soil nitrate N content at both HV and rye treatments decreased continuously with the lapse of days after planting (DAP) and was lowest at 75 DAP: 44 mg/kg and 52 mg/kg the for the HV and rye treatment without urea, respectively. CONCLUSION: These results indicate that the N mineralized from the soil incorporated HV or rye accounts for an important portion of N available for the growth and fruit yield of watermelon. It can be suggested that the green manures, comparable to ureacould ensure the yield of watermelon, if soil nitrate N content isabove 40 mg/kg by soil incorporation of HV and rye during watermelon cultivation. However, further studies on the relationship between soil nitrate N content during cultivation periods and the fruit yield of watermelon are required.