• Asian-Australasian Journal of Animal Sciences
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• 제11권6호
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• pp.697-701
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• 1998

In order to improve silage quality and utilization of napier grass (Pennisetum purpureum Schum.) by goats, the grass was ensiled with molasses (MOL) and/or defatted rice bran (DRB). Napier grass was harvested at the growing stage in July and cut into 3 cm length. The grass was mixed with 4% MOL and/or 15% DRB, ensiled 15 kg each into plastic bags and stored for 9 months. Dry matter content of the silage ensiled with MOL (MOL-silage) was 13.4%, but increased to 20% with DRB addition. The addition of MOL decreased pH value and ammonia nitrogen content, but increased lactic acid content. MOL-silage contained about 6% spoilage, but addition of DRB decreased spoilage to less than 1%. Goats were fed the silage at a level of 2.25% (DM basis) of their body weight. Goats fed DRB- or MOL/DRB-silages maintained nitrogen retention, but goats fed MOL-silage did not. The rumen fluid of goats fed DRB-silage tended to be higher in acetic acid and lower in propionic acid than those fed the other silages. Ammonia in the rumen fluids, urea nitrogen in the blood and the urinary nitrogen excretion were the lowest in goats fed MOL/DRB-silage. As the result, the ratio of retained nitrogen to nitrogen intake was the highest in goats fed MOL/DRB-silage. In conclusion, addition of DRB to napier grass increased DM of silage and decreased the volume of spoilage. The combination of MOL and DRB can improve the fermentation quality and thus enhance the utilization of the silage by goats, more than the MOL or DRB being as a single treatment.

• Journal of Ecology and Environment
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• 제30권2호
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• pp.161-170
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• 2007

The ultimate target of restoring waste landfills is revegetation. The most effective method for increasing species richness and biomass in nutrient limited waste landfills is the use of fertilizers. The aim of the present study was to investigate the effects of nitrogen fertilizer, and the addition of carbon through sawdust, sucrose and litter, on vegetation dynamics at a representative municipal waste landfill in South Korea: Kyongseodong. A total of 288 permanent plots $(0.25m^2)$ were established and treated with nitrogen fertilizer (5, 10 and $20Ng/m^2$), sawdust $(289g/m^2)$ sucrose $(222g/m^2)$ and litter $(222g/m^2)$. The aboveground biomass was significantly enhanced by nitrogen fertilizer at 5 and $10Ng/m^2$, compared with the control plots. The total cover of all plant species increased significantly on plots treated with 5 and $20Ng/m^2$, as well as on those treated with sawdust and sucrose, compared with the control plots. The higher species richness after nitrogen fertilization of 10 to $20Ng/m^2$, and the sawdust and sucrose treatment demonstrated that this was an appropriate restoration option for nutrient deficient waste landfills. This study demonstrated positive nutrient impacts on plant biomass and species richness, despite the fact that municipal waste landfills are ecosystems that are highly disturbed by anthropogenic and internal factors (landfill gas and leachate). Adequate N and C combined treatments will accelerate species succession (higher species richness and perennial increase) for restoration of waste landfills.

• 한국재료학회지
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• 제23권11호
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• pp.649-654
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• 2013

The effect of interstitial elements on the ductile-brittle transition behavior of austenitic Fe-18Cr-10Mn-2Ni alloys with different nitrogen and carbon contents was investigated in this study. All the alloys exhibited ductile-brittle transition behavior because of unusual low-temperature brittle fracture, even though they have a faced-centered cubic structure. With the same interstitial content, the combined addition of nitrogen and carbon, compared to the sole addition of nitrogen, improved the low-temperature toughness and thus decreased the ductile-brittle transition temperature (DBTT) because this combined addition effectively enhances the metallic component of the interatomic bonds and is accompanied by good plasticity and toughness due to the increased free electron concentration. The increase in carbon content or of the carbon-to-nitrogen ratio, however, could increase the DBTT since either of these causes the occurrence of intergranular fracture that lead to the deterioration of the toughness at low temperatures. The secondary ion mass spectroscopy analysis results for the observation of carbon and nitrogen distributions confirms that the carbon and nitrogen atoms were significantly segregated to the austenite grain boundaries and then caused grain boundary embrittlement. In order to successfully develop austenitic Fe-Cr-Mn alloys for low-temperature application, therefore, more systematic study is required to determine the optimum content and ratio of carbon and nitrogen in terms of free electron concentration and grain boundary embrittlement.

• Journal of Microbiology and Biotechnology
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• 제24권9호
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• pp.1207-1215
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• 2014

Candida albicans, the major human fungal pathogen, undergoes morphological transition from the budding yeast form to filamentous growth in response to nitrogen starvation. In this study, we identified a new function of GST2, whose expression was required for filamentous growth of C. albicans under nitrogen-limiting conditions. The Gst2p showed Gst activity and required response to oxidative stress. The ${\Delta}gst2$ mutant displayed predominantly yeast phase growth in low ammonium media. Such morphological defect of ${\Delta}gst2$ mutants was not rescued by overexpression of Mep2p, Cph1p, or Efg1p, but was rescued by either overexpression of a hyperactive $RAS1^{G13V}$ allele or through exogenous addition of cyclic AMP. In addition, the ${\Delta}gst2$ mutants had lower levels of RAS1 transcripts than wild-type cells under conditions of nitrogen starvation. These results were consistent with the Ras1-cAMP pathway as a possible downstream target of Gst2p. These findings suggest that Gst2p is a significant component of nitrogen starvation-induced filamentation in C. albicans.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권6호
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• pp.441-448
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• 2000

Experimental work was carried out on nitrogen and phosphorus removal from real wastewater using a bench-scale SBR process. The phosphorus removal was stable and the phosphorus concentration remaining in the reactor was maintained within 1.5ppm, regardless of the addition of an external carbon source. In the case of nitrogen, an external carbon source was necessary for denitrification. The effect on denitrification with the addition of various carbon sources, such as glucose, methanol, acetate, and propionate, was also investigated. Acetate was found to be the most effective among those tested in this study. When 100ppm (theoretical oxygen demand) of sodium acetate was added, the average rate of denitrifiaction was 2.73mg NO$_3$-N (g MLSS)(sup)-1 h(sup)-1, which was ca. 4 times higher than that with the addition of 200 ppm of methanol. The phosphorus and nitrogen concentrations were both maintained within 1.5ppm by the addition of an appropriate amount of a carbon source during a long-term operation of the SBR. The mathematical modeling was performed using Monod kinetics, other microbial kinetics, mass balances, and stoichiometry. The modeling was found to be useful for predicting the SBR operation and optimizing the HRT.

• 한국식품영양과학회지
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• 제28권4호
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• pp.760-765
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• 1999

Changes in physiochemical properties of Sunchang sikhe kochujang, the most famous traditional kochujang, by red ginseng addition(1, 2 and 5% red ginseng on the total weight basis) were investigated. Measurements of physiochemical parameters such as reducing sugar content, alcohol content, amino type nitrogen content and color difference value were conducted during fermentation at 25oC for 120 days. Alcohol content was increased from the begining of fermentation, reaching at the highest level after 90 days of fermentation and then slowly reduced. Alcohol content of red ginseng kochujang was generally higher than that of control kochujang after 90 days of fermentation. Crude protein content of control kochujang and red ginseng kochujang were reduced during fermentation whereas amino type nitrogen content were gradually increased during fermentation. Amino type nitrogen content of red ginseng kochujang appeared to be slightly lower than that of the control kochujang. The reduction in amino type nitrogen content of red ginseng kochujang was negatively related to the level of red ginseng addition. Among color difference values, L and b value of both control kochujang and red ginseng kochujang were reduced by 30 days from the begining of fermentation and then started to be increased.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1667-1671
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• 2003

A computer program to calculate properties of nitrogen is developed. Procedures for the calculation is briefly discussed. The program calculates unknown thermodynamic properties fixing the state with two independent input properties. If input value by user is inappropriate, it displays an error message and replaces the input value with an appropriate one. In addition user can change units with easy. The program developed in this work can be utilized to calculate parameters required for the simulation and design of an equipment using nitrogen.

• 한국유기농업학회지
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• 제13권2호
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• pp.211-221
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• 2005

This experiment was conducted to evaluate the effect of animal slurry on nitrogen uptake of hairy vetch and growth of chinese cabbage in cropping system. Hairy vetch was seeded on September 20 in 2003 . We examined the effect of cover crop(hairy vetch (Vicia villosa Roth) and slurry application(0, l00, 200kg N/ha) on yield and N uptake. Dry matter yield and nitrogen uptake of hairy vetch were measured. The chinese cabbage succeeding cover crop was harvested in 2004. The nitrogen uptake of hairy vetch was 84, 121, 148kg N/ha respectively, when the slurry application was 0, 100 and 200kg N/ha. In addition. N uptake of hairy vetch at the plot of 100kg and 200 kg N/ha slurry were 44% and 76% higher than that of the plot without slurry application respectively. Slurry application of hairy vetch could increase nitrogen uptake by application of green manure at the harvesting time. the content of organic matter and P-content of soil with hairy vetch plot was higher than that of fallow plot due to inhibition of soil erosion. The organic matter levels tend to improve with the addition of hairy vetch. Hairy vetch could improve soil quality by reducing erosion compared with bare fallow. The green manure of hairy vetch with animal slurry maintained soil nutrient and reduced nitrogen fertilizer of chinese cabbage. The hairy vetch residues decomposed rapidly releasing half of their residues within 40 days after burial. The yield of chinese cabbage was 90% in the plot of manure of hairy vetch compared with chemical fertilizer. The yield in the plot treated with green manure of hairy vetch and 50% of chemical fertilizer was reduced 5% less than that of chemical fertilizer. Therefore, it was estimated that the green manure of hairy vetch-chinese cabbage cropping system could reduce nitrogen chemical fertilizer as much as 84~148kgN/ha. the green manure of hairy vetch with animal slurry maintained soil nutrient and reduced nitrogen fertilizer of chinese cabbage.

• Mycobiology
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• 제33권1호
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• pp.23-29
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• 2005

The effects of different concentrations of three amino acids as carbon and or nitrogen sources on mycelial dry weights, changes in pH values of synthetic medium, ammonia secretion and extracellular protease activity by three zoosporic fungi, pathogens of fish and shellfish, were studied. As compared with the control, the addition of isoleucine and aspartic acid as nitrogen sources were generally stimulative for mycelial dry weight production whereas phenylalanine was inhibitory irrespective to the tested fungal species. When amino acids served as carbon and nitrogen sources, the mycelial dry weights of the three fungi were increased (mostly non-significantly) relative to untreated control but weights were decreased as the concentrations of the three amino acids raised. The addition of individual amino acids as carbon and nitrogen sources to the medium significantly increased pH values of the medium comparable to the control. The addition of each of the three amino acids as carbon and nitrogen sources to the medium significantly induced ammonia secretion by the three species of zoosporic fungi. Ammonia secretion in synthetic medium amended with amino acids as nitrogen source raised by the three zoosporic fungi relative to untreated control except in case of Achlya racemosa treated with isoleucine. Extracellular protease activity was almost promoted in case of Achlya proliferoides and Saprolegnia furcata cultures treated with isoleucine and aspartic acid individually in presence of glucose and vice versa in case of phenylalanine. However, extracellular protease activity of A. racemosa decreased compared with the control at various concentrations of isoleucine and both phenylalanine and aspartic acid assumed inconsistent effects. Extracellular protease activity of the three zoosporic fungi in the medium devoid of glucose varied depending upon zoosporic fungal species, the tested amino acid and the applied concentrations. The values of protease activity were approximately less two folds than that obtained in presence of glucose.

• 환경생물
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• 제24권2호
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• pp.186-194
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• 2006

Nitrogen dynamics of Seagrass Zostera marina were investigated in both Dongdae Bay and Ojiri from March to August, 2004. All seagrass samples were separated into four fractions such as leaves (new and adult), sheath and rhizome in order to understand temporal variations of nitrogen content in different fractions of Zostera marina. There are temporal variations of shoot production rates and total nitrogen contents in their different fractions at both study areas. Leaf production were almost 4 to 5 fold higher in summer than in winter. The irradiance is the primary factor controlling the leaf production of Zostera marina in both sites although water temperature also influence its productivity. Nitrogen contents of leaves were overall low in summer than in winter, but nitrogen content of rhizome increased during the summer season. In addition, nitrogen contents of new leaves were mostly higher than adult leaves in spite of lower nitrogen content of new and adult leaves in high productivity period. This result suggests that Zostera marina seems to have significant translocation ability of nitrogen in a shoot. The nitrogen content of leaf tissue may reflect nutritional nitrogen availability.