• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.69-69
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• 2001

We report a study of the nitriding of the martensitic grade of stainless steel AKSK 420 in a low-pressure rl discharge using pure nitrogen. Much studied samples of the austenitic grade AISI 304 were treated at the same time to provide a comparison. With a treatment time of 4.0 h at $400^{\circ}C$, the nitrogen-rich layer on MSK 420 is 20pm thick and has a hardness about 4.3 times higher than that of the untreated material. The layer thickness is much greater than that obtained on AISI 304 under identical treatment conditions, reflecting the different Cr content of the two alloys. The alloy AlISI 420 is more susceptible than AISI 304 to the formation of CrN and ferrite, and this has a deleterious effect on the hardnes, gain. Below the temperature at which CrN forms, the treated layer retains its martensitic structure, but with a larger lattice parameter than the bulk, a phase that we term expanded martensite, by analogy with the situation with austenitic stainless steel. The fact that the treated layer retains a martensitic structure is interesting in view of previous evidence that nitrogen is an austenite stabilizer.

• Journal of Applied Biological Chemistry
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• v.54 no.2
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• pp.143-146
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• 2011

Novel pyrazoline (4) was synthesized from chalcone (3) which was prepared from 2'-hydroxy-l'acetonaphthone (1) and 4-methoxy benzaldehyde (2). Pyrazoline (4) forms resonance assisted hydrogen bond between naphthol hydroxyl group and imine nitrogen in a pyrazoline ring. Pyrazoline (4) shows Poly ADP-ribose Polymerase (PARP) cleavage ability as a proof of apoptosis in cancer cell, which reveals its anti-cancer property.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.295-297
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• 2003

Cryogenic systems is requirement for the operation of HTS power cables. In general, HTS power cables require temperature below 77K, a temperature that can be achieved from the liquid nitrogen or sub-cooled LN2. HTS power cable is needed for sufficient refrigeration to overcome its low temperature heat loading. This loading typically comes in two forms : (1) heat leaks from the surroundings and (2) internal heat generation. This paper is a explanation for the cooling test of 10m HTS power cable.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.144-147
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• 2004

Organosilicon polymers have long paid attention as functional polymers [1,2]. Among others, poly- (1-trimethylsilyl-1-propyne) [PTMSP] is a polymer, which forms a gas separating membrane with extraordinary high gas permeability. In particular, composite membranes that constituted two different matrices (inorganic and organic) have been recently developed in order to improve the permeation characteristics.(omitted)

• Korean Journal of Environmental Agriculture
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• v.22 no.3
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• pp.197-202
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• 2003

Phosphorus is one of the major plant growth limiting nutrients, despite being abundant in soils in both inorganic and organic forms. Phosphobioinoculants in the form of microorganisms can help in increasing the availability of accumulated phosphates for plant growth by solubilization. Penicillium oxalicum CBPSTsa, isolated from paddy rhizosphere, was studied for its phosphate solubilization. The influence of various carbon sources like glucose, sucrose, mannitol and sorbitol and nitrogen sources like arginine, sodium nitrate, potassium nitrate, ammonium chloride and ammonium sulphate were evaluated using liquid media with tricalcium phosphate (Ca-P), ferric phosphate (Fe-P) and aluminium phosphate (Al-P). Maximum soluble phosphate of 824 mg/L was found in the amendment of sucrose-sodium nitrate from 5 g/L of Ca-P. Mannitol, sorbitol, and ariginine were poor in phosphate solubilization. While sucrose was better carbon source in solubilization of Ca-P and Al-P, glucose fared better in solubilization of Fe-P. Though all the nitrogen sources enhanced P solubilization, nitrates were better than ammonium In the amendments of ammonium chloride and ammonium sulphate, higher uptake of available phosphates by the fungus was found, and this resulted in depletion of available P in Fe-P amendment Phosphate solubilization was accompanied by acidification of the media, and the highest pH decrease was observed in glucose amendment Among the nitrogen sources, ammonium chloride favored greater pH decrease.

• Microbiology and Biotechnology Letters
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• v.47 no.1
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• pp.11-19
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• 2019

The properties of microalgae as bioresources for biodiesel production can be improved by adding nitrogen sources into the culture medium. Thus, Nannochloropsis oceanica CCAP 849/10 was cultured in f/2 media supplemented with five different forms of nitrogen at $0.88mmol-N\;l^{-1}$ each: ammonium bicarbonate ($NH_4HCO_3$), ammonium sulfate ($(NH_4)_2SO_4$), sodium nitrate ($NaNO_3$), ammonium nitrate ($NH_4NO_3$), and urea. The cell density, lipid content, and fatty acid profile of the microalga were determined after 15 days of cultivation. The growth of N. oceanica based on cell number was lowest in the medium with $NH_4NO_3$, and increased significantly in the medium with $NH_4HCO_3$. Cells treated with $(NH_4)_2SO_4$, and $NH_4NO_3$ produced the highest total lipid contents (i.e., 65% and 62% by dry weight, respectively). The fatty acid profiles of the microalga were significantly different in the various nitrogen sources. The major fatty acids detected in cultures supplemented with $NH_4HCO_3$, $(NH_4)_2SO_4$, $NH_4NO_3$, or urea were C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, C20:5, and C22:6. However, the C16:1 content in the $NaNO_3$-supplemented culture was very low. This study highlights that the nitrogen source can strongly influence lipid production in N. oceanica and its fatty acid composition.

• Korean Journal of Soil Science and Fertilizer
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• v.7 no.2
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• pp.119-125
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• 1974

Uptake amount, percent translocation to grain and grain yield efficiency of N. P. K. Si were investigated with N. P. K simple trials (countrywide, 1967~69) and other nitrogen fertiltzer field trials in relation to yield class. 1) Uptake rate with yield increase were similar in all nutrients but silica showed greater yearly variation. 2) In N. P. K simple trials showing very low nitrogen efficiency(46kg grain/ nitrogen uptake kg) it and percent translocation increased with yield increase. 3) Nitrogen efficiency deacreased with the increase of nitrogen uptake and the decreasing rate depends greatly on fertilizer forms and variety. Nitrogen efficiency was greater in sandy loam where yield was higher than in clay loam. 4) Nitrogen efficiency positively correlated with percent translocation. 5) In high yielding fields yield was attributed only to the increase of nitrogen uptake, keeping efficiency around 50. 6) Major factor for high yield is considered as the increase of nitrogen efficiency rather than nitrogen uptake. 7) Phosphorus efficiency in N. P. K. simple trials was considerably low, suggesting too much uptake due to soil reduction.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 1997.10a
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• pp.1.1-32
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• 1997

Atmospheric monitoring capabilities were established in 1988 by the University of Florida at Duke forest, near Durham. NC: Cary forest, near Gainesville, FL: and Austin forest, near Nacogdoches, TX. Continuous (hourly averaged) measurements of air quality (ozone, nitrogen oxides and sulfur dioxide) and meteorological variables were made at these three low elevation (< 200 meters), rural locations in the southeastern U.S. for more than three years. During the same period at these sites wet and dry acid deposition samples were collected and analyzed on an event and weekly basis, respectively The monitoring locations were selected to determine actual atmospheric exposure indices for southern pine species in support of on-site surrogate exposure chamber studies conducted by Southern Commercial Forest Research Cooperative (SCFRC) investigators. Daily and quarterly averaged ozone maxima were higher (55 ppb) at the northernmost site in the network (Duke forest) in the second and third quarters (spring and summer seasons) and lower (35 ppb) in the first and fourth quarters (winter and fall seasons), when compared to ozone levels at the two southernmost sites (Cary and Austin forests). Seasonal ozone levels at the latter two sites were similar Nitrogen oxieds and sulfur dioxide levels were insignificant (< 5 ppb) most of the time at all sites, although soil emissions of NO at two sites were found to influence nighttime ozone concentrations. Typical maximum quarterly and annual aggregate ozone exposure indices were significantly higher at Duke forest (92.5/259 ppm-hr) than those values observed at the two southern sites (65.6/210 ppm-hr). Acid deposition (wet and dry) components concentrations and deposition fluxes observed at the Duke forest, NC piedmont site, were generally greater, dependent on site and season, than corresponding variables measured at either of the two southern coastal plain sites (Cary and Austin forests). Acid deposition variables observed at the latter two sites were remarkably similar, both qualitatively and quantitatively, although the sites were located 1300 km apart. A comparison of deposition fluxes of elemental nitrogen (NO3, NH4') and sulfur (5042-, SO3) components in wet and dry forms indicated that wet deposition accounts for approximately 70% of the total nitrogen and 73% of the total sulfur input on an annual equivalent basis at all sites.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.408-412
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• 2019

In this study, nitrogen doped carbon felt was prepared by pyrolysis of urea at high temperature and applied as an electrode for vanadium redox flow cell. Urea is easier to handle than ammonia and forms $NH_2$ radicals at higher temperatures, creating a nitrogen functional group on the carbon surface and acting as an active site in the vanadium redox reaction. Therefore, the discharge capacity of activated carbon felt electrodes using urea was 14.9 Ah/L at a current density of $150mA/cm^2$, which is 23% and 187% higher than OGF and GF, respectively. These results show the possibility that activated carbon felt electrode using urea can be used as electrode material for redox flow battery.

• The Korean Journal of Ecology
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• v.26 no.3
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• pp.135-142
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• 2003

Four legume plants showed better growth by the external nitrogen supply rather than the symbiotic nitrogen fixation only under salt additions. In case of Glycine max and Phaseolus angularis, total nitrogen contents decreased by high salinity level but their amino acid levels significantly increased with the increase of salt treatments and indicated high soluble-/insoluble-N ratios. Cassia tora and Albizzia julibrissin contained less amino acids than G. max and P. angularis but total N (esp. insoluble N fraction) increased with higher salt levels. Asparagine occurred as a main amino acid especially in G. max and P. angularis and can be seen as potential N-storage form in these plants. It might be play an important role for the osmoregulation mechanism under the saline condition. Meanwhile, to investigate what kinds of nitrogen sources are effective for overcoming salt stress on soybean plants, various N forms and concentrations (NH₄NO₃-N, NO₃-N, NH₄NO₃-N; 2.5 and 5 mM) were additionally supplied to the salt gradient medium. Soybean plants treated with NH₄NO₃-N showed the best growth up to 40 mM NaCl and NO₃- fed plants indicated good growth even at 80 mM NaCl treatments. Contrary to NH₄NO₃- and NO₃- fed plants, NH₄/sup +/- fed plants showed remarkable growth reduction and died by 40 and 80 mM NaCl treatments after the first harvest (15th day). Consequently, these results suggest that salt excluding and resistant capacities of soybean plants under NaCl treatments are increased in order of NH₄ - N, control, NO₃- N and NH₄NO₃- N depending on N concentration except NH₄- N treatments.