• Archives of Pharmacal Research
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• 제29권10호
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• pp.879-883
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• 2006

To develop a $^{13}C-urea-containing$ capsule for more economic and sensitive diagnosis of Helicobacter pylori infection, the $^{13}C-urea-containing$ capsules were prepared with various additives such as polyethylene glycol, microcrystalline cellulose, sodium lauryl sulfate and citric acid. Their dissolution test and $^{13}C-urea$ Breath Test in human volunteers were then performed. Polyethylene glycol increased the initial dissolution rates of urea and difference ${\sigma}$ $^{13}C$ values from $^{13}C-urea$, while microcrystalline cellulose and sodium lauryl sulfate decreased them. Irrespective of addition of citric acid, the compositions with polyethylene glycol showed higher values from $^{13}C-urea$ compared to a commercial 76 mg $^{13}C-urea-containing$ capsule due to higher initial dissolution rate. The capsules with 38 mg $^{13}C-urea$ and 1.9 mg polyethylene glycol, which showed higher Helicobacter pylori-positive value of about $8{\textperthousand}$ at 10 min, improved the sensitivity of $^{13}C-urea$ in human volunteers. Thus, the $^{13}C-urea-containing$ capsule with polyethylene glycol would be a more economical and sensitive preparation for diagnosis of Helicobacter pylori infection.

• Asian-Australasian Journal of Animal Sciences
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• 제6권4호
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• pp.619-622
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• 1993

Rumen bacterial amino acids in sheep on urea diet were monitored to assess a possible change in amino acid synthesis as a long term response to high rumen ammonia environment. A sheep was fed a semipurified diet with soybean meal, followed by a diet with urea as a main nitrogen source. Mixed rumen bacteria were harvested from ruminal fluid taken 3 h after feeding (twice in soybean meal feeding and 6 times in urea feeding) and fractionated as cell wall, proteins and protein-free cell supernatant of monitor amino acids in each fraction. Ruminal ammonia concentration at the sampling ranged from 5.7 to 39.5 mgN/dl. Cell wall and protein fractions of mixed rumen bacteria were stable in their amino acid composition regardless of nitrogen sources of diet and the feeding duration. However, protein-free cell supernatant fraction showed a higher alanine proportion with urea feeding (18.6 and 28.2 molar % of alanine for samples from sheep fed soybean meal and urea, respectively) and its duration (20.6 and 32.9 molar % for samples from sheep on urea diet for 1 and 65 days, respectively). Total free amino acid level of bacteria was depressed in the initial period of urea feeding but restored on 65th day of the feeding. These results suggest that an alanine synthesizing system may develop in rumen bacteria as urea feeding becomes longer.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.521-527
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• 2005

The effects of an urae injection at the exhaust pipe for a 4-cylinder DI(Direct Injection) diesel engine are investigated experimentally. The urea quantity was controlled by NOx quantity and MAF(Manifold Air Flow). The urea injection must be precisely metered and then I used the urea syringe pump. I have tested 4 kinds of items that were with the EGR base engine and without the EGR engine. Then I tested each urea-SCR(Selective Catalytic Reduction) system. As the results, I can caculate the SUF(Stoichiometric Urea Flow) and visualize the NOx results by variation of engine speed and engine load. Also, I can make the NOx map. Therfore, I knew that NOx reduction effects of the urea-SCR system without the EGR engine were better than the with EGR base engine except of low load and low speed.

• 한국토양비료학회지
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• 제44권4호
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• pp.545-550
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• 2011

Urea intercalated into montmorillonite (MT) exhibits remarkably enhanced N use efficiency, maintaining its fast effectiveness. This study dealt with the release property of urea from metal-urea-clay hybrid with MT (MUCH) under continuous-flow conditions and the cumulative impacts of its successive application on physicochemical properties of soils. Releases of urea were completed within 4 hrs under continuous-flow condition regardless of the types and the leaching solutions. However, urea release property was significantly affected by both the form of fertilizer and the presence of electrolytes in solution. The fast release property of urea from MUCH in continuous-flow condition was not significantly affected by soil properties such as soil pH and soil texture. In addition, its successive application did not lead to any noticeable change in soil physicochemical properties, water stable aggregate rate, water holding capacity and cation exchange capacity in both sandy loam and clay loam soils. Therefore, this study strongly supported that urea intercalated into MT could be applied as fast-effective N fertilizer, in particular for additional N supply.

• Korean Chemical Engineering Research
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• 제57권3호
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• pp.387-391
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• 2019

A highly porous Ni@MIL-101catalyst for urea oxidation was synthesized by anchoring Ni into a Cr-based metal-organic framework, MIL-101, particles. The morphology, structure, and composition of as synthesized Ni@MIL-101 catalysts were characterized by X-Ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electro-catalytic activity of the Ni@MIL-101catalysts towards urea oxidation was investigated using cyclic voltammetry. It was found that the structure of Ni@MIL-101 retained that of the parent MIL-101, featuring a high BET surface area of $916m^2g^{-1}$, and thus excellent electro-catalytic activity for urea oxidation. A $urea/H_2O_2$ fuel cell with Ni@MIL-101 as anode material exhibited an excellent performance with maximum power density of $8.7mWcm^{-2}$ with an open circuit voltage of 0.7 V. Thus, this work shows that the highly porous three-dimensional Ni@MIL-101 catalysts can be used for urea oxidation and as an efficient anode material for urea fuel cells.

• Journal of Plant Biology
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• 제5권2호
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• pp.6-12
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• 1962

For the comparison with the previous paper (4) the present report deals with the absorption and metabolism of urea and other nitrogen ions in barley seedling absorbed through root. 1. The amount of nitrate in barley treated with urea reach it peak on the 8th day. NO3 on the 4th, NH4 on the 6th or 8th, respectively. 2. The ammonia content in urea group reaches its peak on the 6th day but other groups on the 4th day. The present data in the urea group show to shorten 4 days compared with that of the previous paper(4). 3. the content of total amide from the present data aare gradully increased on all of the groups during this experiment. These are agreement with the result of the previous paper (4). 4. the alcohol solution nitrogen in the urea gorup shows the similar tendency to the NaNO3 group but reaches it peak 2 days later than in the (NH4)2SO4 group. 5. The content of total nitrogen in the urea series has the lowest amount at the beginning while the richest from the 4th day after. These would be explained on that the absorption of urea is delayed and the PH in the urea solution does not change, so called "physiological neutrality". The author should like express his sincere thanks to Prof. M.J.Lee of Seoul National University for his valuable advices.e advices.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.306-312
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• 1998

This paper describes syntheses of thickener for di-urea grease using constant velocity joint. The thickeners of di-urea grease were synthesized by reaction of diisocyanate with various alkylamines, hexylamine, octylamine, stearylamine and cyclohexylamine at high temperatxire. The synthesized thickener were analyzed by FT-IR spectroscopy and two kinds of Mass spectroscopy (EI & FAB). Dropping point and Consistency of synthesized di-urea grease were determined.

• 한국축산시설환경학회지
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• 제3권1호
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• pp.43-48
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• 1997

This experiment was conducted for the effects of application levels of slurry and urea on the production of silage corn. The result was as follows; 1. DM yield of silage corn was the highest in the 100kg/ha level of urea and 160kg/ha of slurry. 2. Crude protein content was increased with increasing slurry and urea. 3. Total N production was increased continuously with increasing slurry in the 100kg/ha of urea, however, it was not affected by 200kg of urea. 4. NDF content was not affected by an application levels of slurry and urea.

• 동력기계공학회지
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• 제13권4호
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• pp.5-10
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• 2009

Urea-SCR system, the selective catalytic reduction using urea as reducing agent, is a powerful technique to reduce nitrogen oxides(NOx) emitted from diesel engines. However, a tank of urea(32.5 wt%)-water solution can be frozen in low ambient temperature levels of below $-11^{\circ}C$. The purpose of this study is to understand freezing and melting phenomena of the urea-water solution, and its can be applied to get the urea-water solution from frozen it within 5 minutes after cold start. Factors considered were the type of heater and the urea tank shape. From the results, it was found that melting volume of cartridge heater B during 5 minutes of heating period was 83ml when supplying electric power of 150W. Horizontal heater B, which was put in the narrow bottom space of the tank T1, had fast melting characteristics.

• 동력기계공학회지
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• 제15권4호
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• pp.42-47
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• 2011

The purpose of this study is to investigate the best melting condition with various winding number of a heating pipe, supplying quantity of engine coolant and coolant temperature at the inlet of the heating pipe. Also, it is to suggest getting method of an appropriate quantity of the agent for the urea-SCR system within 10 minutes. For this matter, this study identifies the temperature distribution of inside of urea-tank while it is frozen at the low temperature condition, and suggests the best melting condition of the frozen urea within 10 minutes. From the results, it was found that 2L of melted urea was obtained by the coolant flow rate of 200L/hr at $70^{\circ}C$ for 10 minutes from the start of engine operating.