• Environmental Engineering Research
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• 제15권3호
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• pp.157-161
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• 2010

Forest soils are often nitrogen-limited, and nitrogen input to forest soils can cause substantial changes in the structure and functions of a soil ecosystem. To determine the effects of nitrogen input on methane oxidation and the microbial enzyme activities, manipulation experiments were conducted using nitrogen addition to soil samples from Mt. Jumbong. Our findings suggested that the addition of nitrogen to the soil system of Mt. Jumbong did not affect the microbial enzyme activities. Conversely, the addition of nitrogen affected the rate of methane oxidation. Inorganic nitrogen in soils can inhibit methane oxidation via several mechanisms, such as substrate competition, toxic effects, and competition with other microbes, but the inhibitory effects are not always the same. In this research, seasonal changes were found to produce different inhibitory factors, and these different responses may be caused from differences in the methantrophic bacteria community structure.

• 한국진공학회지
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• 제8권2호
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• pp.165-171
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• 1999

Diamond-like carbon(DLC) films were synthesized using the rf-plasma CVD technique with the addition of small amounts of nitrogen and oxygen to a gas mixture of $CH_4$ and $H_2$. The gas flow ratio of $CH_4$ to $H_2$ was 2.4:1, and 3% , 13.6% of nitrogen were added to the gas mixture of $CH_4$ and $H_2$ for the deposition of DLC films. The film stress tended to decrease as the nitrogen concentration increased from 3% to 13.6%, probably due to the decrease of the number of the interlink between carbon atoms. The residual stress tended to slightly decrease when 3% of oxygen was added. Scratch tests were performed to investigate the adhesion between the DLC films and the Ti intelayer after pretreating the TiN surface with direct hydrogen plasma. The adhesion was enhanced by adding nitrogen and oxygen to the $CH_4$ and $H_2$ gas mixture. The adhesion for the 3% nitrogen addition was better than that for the 13.6% nitrogen addition. The Vicker's hardness of the DLC films was measured to be 1100Hv.

• 한국연초학회지
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• 제12권2호
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• pp.91-101
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• 1990

A field experiment was conducted to find out the effects of field productivity, variety and nitrogen rate on the yield, quality, chemical constituents and physical properties of burley cured leaf in three field with different productivity(Degree of field productivity: A ; high, B ; medium, C : low) during successive two years(1988~89). The yield and quality were remarkably lowered when nitrogen fertilizer being applied much in low productive field. As compared with Burley 21, KB101 showed high yield, particularly the yield of KB101 in low productive field was relatively high. The effect of nitrogen rate on the yield was somewhat different according to field productivity and production year. When the nitrogen fertilizer being applied above 22.5kg/10a, the added nitrogen had no effect on the yield. Total nitrogen content of cured leaf grown in low productive field was high while total alkaloid was low, therefore total alkaloid/total nitrogen ratio was remarkably low. The lightness, red and yellow color of cured leaf grown in low productive field was remarkably low. As compared with Burley 21, the contents of total alkaloid and total nitrogen and shatter resistance index of cured leaf was somewhat low, while the filling power, lightness, red and yellow color were slightly high. Total nitrogen content of cured leaf was increased remarkably by nitrogen addition, but total alkaloid was not increased though the nitrogen fertilizer being applied above 22.5kg/10a. The filling power and shatter resistance index of cured leaf grown in high nitrogen plot, and the lightness and yellow color were low while the red color was relatively high. It comes into question that the visual quality being increased as well as increment of yield and nitrogenous compounds by nitrogen addition in high productive field. In low productive field, it is considerable that nitrogen addition for high yield should be prohibited because it causes the decrement of yield and quality, on the contrary.

• The Korean Journal of Ecology
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• 제26권2호
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• pp.71-74
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• 2003

Effects of nitrogen addition on the growth of Indigofera pseudo-tinctoria (Leguminosae) in the waste landfill site was investigated. Nitrogen fertilization in the nitrogen poor soils of waste landfill may influence the growth of nitrogen fixing plants beneficially or detrimentally. When I. pseudo-tinctoria was fertilized with three different levels of nitrogen, the coverage of plants treated with 46 g N/$m^2$ and 460 g N/$m^2$ was significantly less than that of plants treated with 23 g N/$m^2$. The growth rates of plant height treated with 46 g N/$m^2$ and 460 g N/$m^2$ were significantly less than those of plants treated with 23 g N/$m^2$. The growth rates of plant diameter treated with 46 g N/$m^2$ and 460 g N/$m^2$ were significantly less than those of plants treated with 23 g N/$m^2$. Dry weights of whole plants in control sites were higher than those of all the others nitrogen treatment sites. Nodule numbers were higher in control plants than those of plants in all the other nitrogen treatment sites. It is suggested that nitrogen fertilizer addition over 23 g N/$m^2$ affect the growth of some nitrogen fixing plants, such as I. pseudo-tinctoria, negatively.

• 한국건설순환자원학회논문집
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• 제11권4호
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• pp.493-500
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• 2023

본 연구에서는 전도성 재료를 혼입한 광촉매 보도블록을 제조하여 질소산화물 제거율에 미치는 영향을 살펴보고 내구성이 향상된 블록을 제조하고자 하였다. 광촉매와 전도성 재료인 활성탄소를 혼입시 광촉매 효율이 향상되었으며 전도성 광촉매 콘크리트 블록의 경우 광촉매 콘크리트 블록보다 질소산화물 제거율이 2.5배 정도 향상되었다. 전도성 광촉매 시험편의 질소산화물 제거율이 높게 나타난 것은 전도성 재료인 활성탄소의 영향으로 TiO₂ 광분해로 인한 광전류가 많이 발생한 영향으로 볼 수 있으며 광촉매 시험편과 전도성 광촉매 시험편의 질소산화물 제거율 실험결과와 광전류 시험결과를 비교 분석하였다.

• 산업기술연구
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• 제39권1호
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• pp.1-5
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• 2019

In this study, we examined the effect of NO addition on the ozone-induced soot oxidation activity of $LaMnO_3$ perovskite catalysts. The addition of 10~20% NO ($NO_2$) with respect to the concentration of ozone effectively enhanced the rate of ozone-induced soot oxidation rate over $LaMnO_3$. However, the excessive addition of NO ($NO_2$) was detrimental to ozone-induced soot oxidation activity. It is supposed nitrogen oxides would adsorb on the catalyst and then react with carbon-oxygen species developed on soot surface, but an excessive addition of nitrogen oxide would inhibit the formation of carbon-oxygen species, which is a key intermediate in the reaction, and consequently suppress the oxidation rate of soot.

• Animal Bioscience
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• 제36권6호
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• pp.920-928
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• 2023

Objective: Angora rabbits fed a low-protein diet exhibit decreased hair production performance. This study was set out to evaluate the effects of methionine on hair properties and nitrogen metabolism in Angora rabbits fed a low-protein diet and to investigate the gene expression related to hair follicle development to determine the possible molecular mechanism of methionine effects on hair follicle development. Methods: An experiment was conducted to investigate the effects of DL-methionine addition on a low-protein diet on hair development in Angora rabbits. Angora rabbits were divided into 5 groups: fed a normal diet (control), fed a low-protein diet (LP), or fed an LP supplemented with 0.2%, 0.4%, or 0.6% DL-methionine (Met). Results: The results showed that rabbits in the LP group had lower wool yield than the control rabbits, but the addition of 0.4% to 0.6% Met to LP attenuated these effects (p<0.05). Dietary addition of 0.4% to 0.6% Met to LP increased the apparent nitrogen digestibility, nitrogen utilization rate, and feed efficiency (p<0.05). Feeding LP decreased the insulin-like growth factor 1 (IGF1), keratin-associated protein (KAP) 3.1, and KAP 6.1 mRNA levels compared with the control, but the addition of 0.4% Met in LP attenuated these effects (p<0.05). Relative to the LP or control group, dietary addition of 0.4% Met increased versican mRNA levels. Conclusion: In conclusion, the addition of Met to LP could improves wool production performance and feed efficiency and reduce nitrogen emissions in Angora rabbits. Met can promote hair follicle development, which may be associated with IGF1, KAP, and the versican signaling.

• 상하수도학회지
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• 제13권2호
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• pp.34-40
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• 1999

Aerobic night-soil treatment effluent containing high concentration of ammonia nitrogen was treated to remove nitrogen using Bardenpho process with Methanol addition. The objective of this study was to investigate the feasibility of complete nitrogen removal at three different HRTs such as 6.25d, 5d, and 3.75d, respectively. At each HRT, the nitrogen removal efficiencies are 92%, 99% and 97% and the required amount of methanol are 3.05gMeOH/gN, 2.75gMeOH/gN, and 3.38gMeOH/gN, respectively. Specific nitrification rates are decreased proportional to HRT and are $0.022gNH_4^+-N/g\;MLVSS{\cdot}day$, $0.0332gNH_4^+-N/g\;MLVSS{\cdot}day$ and $0.051gNH_4^+-N/g\;MLVSS{\cdot}day$ and specific denitification rate are decreased proportional to HRT and are $0.0210g\;N/gMLVSS{\cdot}day$, $0.0330g\;N/gMLVSS{\cdot}day$ and $0.0525g\;N/gMLVSS{\cdot}day$, respectively.

• Applied Biological Chemistry
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• 제14권1호
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• pp.99-102
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• 1971

Saccharomyces rouxii $T_9$의 생육에 있어서 질소원 및 무기염류의 영향을 실험한 결과는 아래와 같다. (1) 무염배지의 경우 유기질소원으로서는 peptone을 $2.5{\sim}5.0%$ 첨가했을때 균의 생육이 가장 양호하였으며 무기질소원으로서는 $(NH_4)_2HPO_4$를 1.0% 첨가했을때 가장 양호하였다. (2) 20% 식염함유배지의 경우 유기질소원으로서는 yeast ext.를 1.5% 첨가했을때 가장 양호하였으며 무기질소원으로서는 urea를 5% 첨가 했을매 가장 양호하였다. (3) 무기염류로서 $NaNO_3$는 무염배지의 경우 1% 첨가했을때 가장 양호하였으나 20% 또 식염함유배지의 경우에는 26% 첨가했을 때보다 5%첨가했을때 더욱 양호 하였다. (4) $MgSO_4$와 $CaCl_2$는 0.5% 첨가한 경우 무염배지에서 보다도 20% 식염함유 배지에서 더욱 효과가 있었으며 $MgCl_2$는 26% 식염함유배지에 1%첨가 했을때 가장 효과가 있었다.

• Journal of Microbiology and Biotechnology
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• 제26권7호
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• pp.1290-1302
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• 2016

Microalgae are being researched for their potential as attractive biofuel feedstock, particularly for their lipid production. For maximizing biofuel production, it is necessary to explore the effects of environmental factors on algal lipid-producing potential. In this study, the effects of nitrogen (N) sources (NO₂-N, NO₃-N, urea-N, NH₄-N, and N-deficiency) and carbon-to-nitrogen ratios (C/N= 0, 1.0, 3.0, and 5.0) on algal lipid-producing potential of Chlorella sp. HQ were investigated. The results showed that for Chlorella growth and lipid accumulation potential, NO₂-N was the best amongst the nitrogen sources, and NO₃-N and urea-N also contributed to algal growth and lipid accumulation potential, but NH₄-N and N-deficiency instead caused inhibitory effects. Moreover, the results indicated that algal lipid-producing potential was related to C/N ratios. With NO₂-N treatment and carbon addition (C/N = 1.0, 3.0, and 5.0), total lipid yield was enhanced by 12.96-20.37%, but triacylglycerol (TAG) yields decreased by 25.52-94.31%. As for NO₃-N treatment, carbon addition led to a 17.82-57.43%/25.86-82.67% reduction of total lipid/TAG yields. When NH₄-N was used as the nitrogen source, total lipid/TAG yields were increased by 46.67-113.33%/28.99-74.76% with carbon addition. The total lipid/TAG yields of urea-N treatment varied with C/N ratios. Overall, the highest TAG yield (TAG yield: 38.75 ± 5.21 mg/l; TAG content: 44.16 ± 4.35%) was achieved under NO₂-N treatment without carbon addition (C/N = 0), the condition that had merit for biofuel production.