• The korean journal of orthodontics
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• v.36 no.6
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• pp.465-473
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• 2006

Objective: This study evaluated the effects of nitric oxide (NO) on the proliferation and differentiation of human periodontal ligament cells involved in orthodontic tooth movement. Methods: A range of concentrations of sodium nitroprusside (SNP), a NO donor, were administered to samples of human periodontal ligament cells, followed by measurement of cell viability, alkaline phosphatase (ALP) activity, and expression of osteonectin and bone sialoprotein. Results: Cell viability, ALP activity and the expression of osteonectin and bone sialoprotein were increased in human periodontal ligament cells treated with SNP concentrations of < 0.2 mM compared with controls, but were decreased with SNP concentrations of > 1.0 mM. Conclusion: NO has a biphasic effect on proliferation and differentiation in human periodontal ligament cells, with a stimulatory effect at low concentrations and an inhibitory effect at high concentrations.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.3
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• pp.195-200
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• 2017

This study was conducted to examine the inhibitory effects of meso-dihydroguaretic acid (MDGA, 1) and its synthetic derivatives (compound 2 and 3) against NO production. MDGA is a lignan component isolated from the bark of Machilus thunbergii Sieb. et Zucc. We synthesized dimethylated MDGA (2), diacetylated MDGA (3) and compared NO inhibition of two derivatives with that of MDGA (1). MDGA (1) and compound 3 showed suppressive effects against the generation of NO in LPS-activated macrophages. RT-PCR analysis suggested that MDGA (1) and compound 3 inhibited NO production through the suppression of iNOS mRNA expression. From these results, diacetylated MDGA (3) can be used as a pro-drug for MDGA.

• Microbiology and Biotechnology Letters
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• v.12 no.4
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• pp.271-276
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• 1984

Effect of C/N ratios on the cell growth, cell lipid, cell protein and fatty acids of Rhodotorula sp. was examined. At low concentration of nitrogen in cultural medium the growth of the yeast was retarded, whereas its growth was favorable at high concentration but lipid yield was decreased due to a high content of cell protein. In order to increase lipid yield, the optimum C/N ratio obtained was 45-50 (5% glucose, 0.0414% nitrogen). During the cultivation cell protein synthesis occurred mainly in initia stage and the lipid was accumulated rapidly at the late phase. The highest content of total fatty acid was observed at the optimum C/N ratio. The higher C/N ratio was the more unsaturation degree of fatty acid decreased. It was attributed principally to a decreased oleic acid with palmitic acid increased. No significant changes occurred in content of other fatty acids.

• Journal of Soil and Groundwater Environment
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• v.8 no.1
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• pp.57-67
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• 2003

Nitrate contamination by human activities is a serious problem to water-supply in agricultural area. Shallow groundwater is the main source of water-supply, but it is very sensitive to contamination. Study area for nitrate contamination is a region of Iljuk, Kyunggi where is an agricultural area having many livestock facilities in various scales. As a result, the points having availability of incoming of external contaminant are 77%, and the ones over the Drinking Water Limit (DWL) are 32～42%. For a nitrogen isotope analysis, all the points having availability of incoming of external contaminant have $\delta$$^{15}$ N-NO$_3$ values over 5$\textperthousand$, and the points of 59% are strongly affected by nitrogen originated from animal wastes. The major source of nitrate in this area is intensive livestock facilities. Even though a livestock facility had enclosed, it affects groundwater quality for a long time. The chemical property of contaminant source is various according to animal species in surface water, but not in groundwater since some solutes are removed by reactions during an inflow to subsurface.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.393-396
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• 2008

The study of nitrogen dilution effect on flame stability was experimentally investigated in non-premixed turbulent lifted hydrogen jet with coaxial air. hydrogen gas was used as a fuel and coaxial air was injected to make flame liftoff. And both of the fuel jet and coaxial air velocity were fixed as $u_F$=200 m/s and $u_A$=16 m/s, while nitrogen diluents mole fraction was varied from 0 to 0.2. For the analysis of flame structure and flame stabilization mechanism, the simultaneous measurement of PIV/OH PLIF had been performed. It was found that the turbulent flame propagation velocity increased as decreasing of nitrogen mole fraction. We concluded that the turbulent flame propagation velocity was expressed as a function of turbulent intensity, even though the mole fraction of nitrogen diluents gas was changed.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.598-603
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• 2023

Electrochemical ammonia production using catalysts offers a promising alternative to the conventional Haber-Bosch process, allowing for ambient temperature and pressure conditions, environmentally friendly operations, and high-purity ammonia production. In this study, we focus on the nitrogen reduction reactions occurring on the surfaces of ruthenium catalysts, employing first-principles calculations. By modeling reaction pathways for nitrogen reduction on the (0001) and (1000) surfaces of ruthenium, we optimized the reaction structures and predicted favorable pathways for each step. We found that the adsorption configuration of N₂ on each surface significantly influenced subsequent reaction activities. On the (0001) surface of ruthenium, the end-on configuration, where nitrogen molecules adsorb perpendicularly to the surface, exhibited the most favorable N₂ adsorption energy. Similarly, on the (1000) surface, the end-on configuration showed the most stable adsorption energy values. Subsequently, through optimized hydrogen adsorption in both distal and alternating configurations, we theoretically elucidated the complete reaction pathways required for the final desorption of NH₃.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.380-385
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• 1997

일체형원자로에서 일차측 압력은 질소와 증기의 분압에 따라 스스로 작동하는 자기가압기에 의해 일정하게 유지된다. 1차계통내 용해된 질소의 양과 압력변화의 폭을 최소화시키기 위해 가압기를 냉각시킬 필요성이 있으며 이를 위해 습식단열재(wet thermal insulation)와 냉각튜브(cooling tube)가 설치되었다. 본 연구에서는 자기가압기 작동에 중요한 역할을 하는 습식단열재의 기본적인 열전달 특성과 설계시 고려해야 할 사항을 분석하였다 전산유체코드를 사용해 단열재내치 온도 및 유동 분포를 계산하였고 기존의 실험으로부터 얻어진 열전달상관식을 이용해 단면충의 개수에 대한 민감도 계산, 돌출지점을 통한 열전도, 열전달 계수의 오차가 설계변수에 미치는 영향 등을 분석하였다.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2003.04a
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• pp.175-180
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• 2003

효율적인 정밀농업을 위해서 선행되어야할 과제로 토양의 물리, 화학 및 생물학적인 특성을 구명하는 것이다. 이를 위해 최근 연구가 활발히 진행되고 있으며, 토양분석을 위한 근적외선 분광분석에 관한 연구는 풍건세토를 시료로 토양수분(곡산, 1989), 전질소, 전탄소, 질산태질소 등(정상 등, 1991)을 정량화 할 수 있다고 보고하였다. 그러나 풍건토의 조제와 분쇄 등으로 토양지도를 작성할 수 는 없다. (중략)

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2007.06a
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• pp.215-217
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• 2007

반도체 집적화 기술의 발달로 반도체 공정에서 디바이스의 선폭은 줄어들고, 박막의 다층화가 필수적인 과정이 되었다. 이에 따라 반도체에서 Si 기판과 금속 배선과의 열적 안정성에 대한 신뢰성이 더욱 중요시 되어가고 있다. 이를 방지하기 위하여 우리는 3개의 화합물로 구성된 Tungsten-Carbon-Nitrogen (W-C-N) 확산방지막을 사용하였다. 실험은 Si 기판위에 W-C-N박막을 물리적 기상 증착법(PVD)으로 질소비율을 변화하며 확산방지막을 증착하여 Si 기판과 W-C-N확산방지막의 특성을 여러 온도 열처리 조건에서 확인하였다. 특성을 분석을 위하여 ${\alpha}-step$과 ${\beta}-ray$를 이용하여 증착률을 확인한 후 4-point probe를 이용하여 비저항을 측정하였고, X-ray Diffraction 분석을 통하여 결정 내부의 변화를 확인하였다. 이를 통하여 W-C-N 확산방지막의 열적인 안정성을 질소변화에 따라 조사하였다.

• Journal of the Korean Vacuum Society
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• v.12 no.2
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• pp.86-92
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• 2003

The pumping characteristics of a commercial UHV cryopump with a G-M refrigerator for various gases were investigated. The pumping speeds as a function of pumped amount of $H_2,\; D_2,\; He,\; Ar,\; N_2$, CO and the pumping capacity of $N_2$ were measured and the trend was theoretically analyzed. The spectrum change of the residual gas was also investigated during cyropump operation.