• Journal of Microbiology and Biotechnology
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• 제32권6호
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• pp.768-775
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• 2022

In this study we aimed to derive the response surface models for Escherichia coli reduction in wheat flour using atmospheric cold plasma (ACP) with three types of gas. The jet-type atmospheric cold plasma wand system was used with a 30 W power supply, and three gases (argon, air, and nitrogen) were applied as the treatment gas. The operating parameters for process optimization considered were wheat flour mass (g), treatment time (min), and gas flow rate (L/min). The wheat flour samples were artificially contaminated with E. coli at a concentration of 9.25 ± 0.74 log CFU/g. ACP treatments with argon, air, and nitrogen resulted in 2.66, 4.21, and 5.55 log CFU/g reduction of E. coli, respectively, in wheat flour under optimized conditions. The optimized conditions to reduce E. coli were 0.5 g of the flour mass, 15 min of treatment time, and 0.20 L/min of nitrogen gas flow rate, and the predicted highest reduction level from modeling was 5.63 log CFU/g.

• 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.

• 한국표면공학회지
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• 제29권5호
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• pp.549-555
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• 1996

Diamond Like Carbon film is amorphous film which is considered to consist of three coordinate graphite structure and tetrahedron coordinate diamond structure. Its hardness, thermal conductivity and chemical stability are nearly to one of diamond. It is well known to become semi-conductor by doping of inpurity. In this study Diamond Like Carbon film was synthesized by Microwave Plasma CVD in the gas mixture of hydrogen-methan-nitrogen and doped of nitrogen on the single-crystal silicon or silica glass. The temperature of substrate and nitrogen concentration in the gas mixture had an effect on the bonding state, structural properties and conduction mechanism. The surface morphology was observed by Scanning Electron Microscope. The strucure was analyzed by laser Raman spectrometry. The bonding state was evaluated by electron spectroscopy. Diamond Like Carbon film synthesized was amorphous carbon containing the $sp^2$ and $sp^3$ carbon cluster. The number of $sp^2$ bonding increased as nitrogen concentration increased from 0 to 40 vol% in the feed gas at 1233K substrate temperature and at $7.4\times10^3$ Pa. Increase of nitrogen concentration made Diamond Like Carbon to be amorphous and the doze of nitragen could be controlled by nitrogen concentration of feed gas.

• 대한수의학회지
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• 제43권4호
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• pp.641-648
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• 2003

Changes of plasma DNA contents and serum biochemical values were measured in rats administered with $HgCl_2$ to investigate the in vivo cytotoxic effects of mercury and examine the usefulness of these changes as indicators of mercury exposure and diagnosis of mercury poisoning. Rats were given once intraperitonealy $HgCl_2$(0.13. 0.32. 0.8 and 2 mg/kg b.w) and the changes of plasma DNA contents and serum biochemical values were measured at the time of 2, 4, 8, 24, 48 and 72 hours after the administration of $HgCl_2$. Plasma DNA contents began to increase from 2 hours after the administration of $HgCl_2$ in all the treatment groups significantly compared to control with dose-dependent pattern. The levels of plasma DNA reached to peak at 48 hours as 2.77, 7.60, 15.46 and 16.51 times higher than control in each treatment group of 0.13, 0.32, 0.8 and 2 mg/kgb.w, respectively and remained to be higher until 72 hours after the administration. The values of creatine kinase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, blood urea nitrogen and glucose of serum were increased, however the values of alkaline phosphatase, total protein and triglyceride were decreased. These changes of increase and decrease showed dose-dependent pattern but the starting time, maintenance and magnitude of change were various and characteristic according to serum biochemical indices. Among the changes of serum biochemical values, those of aspartate aminotransferase, lactate dehydrogenase and blood urea nitrogen were apparently and significantly increased compared to control from 2 to 72 hours by the administration of 2 mg/kg $HgCl_2$. This study demonstrates that plasma DNA and serum biochemical values such as aspartate aminotransferase, lactate dehydrogenase, blood urea nitrogen and etc. are valuable as biomarkers for mercury exposure assessment and diagnosis of mercury poisoning.

• Asian-Australasian Journal of Animal Sciences
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• 제12권8호
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• pp.1298-1309
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• 1999

The nutritional value of protein varies between feedstuffs. It is possible to feed animals using crystalline amino acids as a sole nitrogen source, but in practice only some limiting amino acids are added to the diet. In order to use feedstuffs efficiently, it is important to determine exact amino acid requirements. Reported values differ widely because the requirements are affected by various factors. In this report, therefore, the factors affecting amino acid requirements are reviewed as follows: 1) availability of dietary amino acids, conversion factors of nitrogen to protein, interaction of amino acids, and strain, sex and age of animals; 2) amino acid requirements for maximum performance and maintenance, usefulness of non-essential amino acids; 3) plasma amino acid concentration as a parameter to determine amino acid requirements; and 4) nitrogen excretion to reduce environmental pollution. These factors should be considered, it is to improve the dietary efficiency, which is to reduce excess nitrogen excretion for environmental pollution.

• Fibers and Polymers
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• 제5권1호
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• pp.52-58
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• 2004

Previous investigation results revealed that after the Low Temperature Plasma (LTP) treatment, the hydrophilicity of wool fiber was improved significantly. Such improvement enhances the wool dyeing and finishing processes which might be due to the changes of the wool surface to a more reactive one. In this paper, wool fibers were treated with LTP with different gases, namely, oxygen, nitrogen and gas mixture (25 % hydrogen/75 % nitrogen). Investigations showed that chemical composition of wool fiber surface varied differently with the different plasma gas used. The surface chemical composition of the different LTP-treated wool fibers was evaluated with different characterization methods, namely FTIR-ATR, XPS and saturated adsorption value. The experimental results were thoroughly discussed.

• Journal of Nutrition and Health
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• 제25권5호
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• pp.397-403
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• 1992

This study was performed to investigate the effect of dietary magenesium on stress reactions in rats having abdominal surgery. Sixty three male rats of sprague-dawley strain were blocked into 3 groups : rats fed regular magnesium (0.05% Mg: control) rats receiving regular magnesium with surgery(Mg-adeq : S) Five weeks after feeding abdominal surgery was performed and randomly chosen 7 rats from each group were sacrificed on 1, 3 and 5 days after surgery. Te following were found ; 1) Rats fed marginal magnesium showed significantly elevated urinary urea nitrogen urinary potassium and plasma glucose compared controls only one day after abdominal surgery but not 3 days or 5 days after surgery 2) Rats fed adequate magnesium did not show any significant change in metabolic stress indicator after surgery. 3) Plasma free fatty acid and cortisol level were not different among groups. 4) Decreased plasma magnesium and potassium level were found in rats fed marginal magne-sium and sacrificed one day and three days after surgery.

• 한국연소학회지
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• 제22권1호
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• pp.23-31
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• 2017

Large-scale fuel tanks emit massive amount of hardly-combustible VOC mixtures which are light hydrocarbon species in dilution with nitrogen and carbon dioxide. We have developed a lab-scale burner to combust those VOC mixtures by use of a turbulent partially-premixed flame as a pilot flame. For a higher HC treatment ratio, the mixture gases were reformed by a rotating arc plasma device. The results showed that the nitrogen mole fraction and the injecting speed of the VOC mixture influence on the performance of the burner. It was also found that the size of the pilot flame and the power supplied to the plasma device determine the overall HC treatment ratio and the concentrations of CO and NOx in the exhaust gas.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.179-179
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• 2016

A radio-frequency (RF) Inductively Coupled Plasma (ICP) torch system was used for boron-nitride nano-tube (BNNT) synthesis. Because of electrodeless plasma generation, no electrode pollution and effective heating transfer during nano-material synthesis can be realized. For stable plasma generation, argon and nitrogen gases were injected with 60 kW grid power in the difference pressure from 200 Torr to 630 Torr. Varying hydrogen gas flow rate from 0 to 20 slpm, the electrical and optical plasma properties were investigated. Through the spectroscopic analysis of atomic argon line, hydrogen line and nitrogen molecular band, we investigated the plasma electron excitation temperature, gas temperature and electron density. Based on the plasma characterization, we performed the synthesis of BNNT by inserting 0.5~1 um hexagonal-boron nitride (h-BN) powder into the plasma. We analysis the structure characterization of BNNT by SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy), also grasp the ingredient of BNNT by EELS (Electron Energy Loss Spectroscopy) and Raman spectroscopy. We treated bundles of BNNT with the atmospheric pressure plasma, so that we grow the surface morphology in the water attachment of BNNT. We reduce the advancing contact angle to purity bundles of BNNT.

• Asian-Australasian Journal of Animal Sciences
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• 제21권3호
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• pp.434-442
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• 2008

The objective of this study was to determine the optimum ratio of methionine to methionine plus cystine for growing pigs. A nitrogen balance trial was conducted using a total of 21 barrows (Large WhiteLandrace) over two replicates. The initial body weight was $20.36{\pm}1.22kg$ (mean${\pm}$SD) in the first replicate and $23.54{\pm}1.02kg$ (mean${\pm}$SD) in the second. For each replicate, the 21 pigs were randomly assigned to one of seven dietary treatments with three observations per treatment. The diets included a methionine and cystine-deficient basal diet with all other essential nutrients meeting nutrient requirements and six diets formulated with graded levels of DL-methionine (0.00, 0.03, 0.06, 0.10, 0.13, 0.16%) and $L-Cystine{\cdot}HCl{\cdot}H_2O$ (0.19, 0.15, 0.11, 0.07, 0.04, 0.00%). This resulted in ratios of methionine to methionine plus cystine of 41.3, 29.6, 35.3, 41.2, 46.0, 51.6 and 57.5%. Each experimental period lasted 12 days consisting of a seven-day adaptation period followed by a five-day total collection of urine and feces. During the collection period, pigs were fed 900 g/day for the first replicate and 1,200 g/day for the second replicate. The feed was provided in three equal portions at 0800, 1500, and 2200 h daily. Pigs had ad libitum access to water after feeding. There was a linear (p<0.01) and quadratic (p<0.01) effect on daily gain and feed conversion as the ratio of methionine to methionine plus cystine increased. Pigs receiving the diets providing a methionine to methionine plus cystine ratio of 51.6% had the best daily gain and feed conversion. Plasma urea nitrogen was also lowest for this treatment. Nitrogen retention increased (p<0.01) as the relative proportion of methionine increased up to 51.6% and then a downward trend occurred at 57.5%. The quadratic regression model, as well as one- and two- slope regression line models, were used to determine the optimum ratio of methionine to methionine plus cystine. Eliminating the 35.3% methionine to methionine plus cystine treatment resulted in $R^2$ values in excess of 0.92. The optimal ratio of methionine to methionine plus cystine was estimated to be 54.15% for nitrogen retention and 56.72% for plasma urea nitrogen.