• Journal of Korean Society for Atmospheric Environment
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• v.34 no.1
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• pp.120-143
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• 2018

The analytical methods and their ambient levels of organic nitrogenous compounds such as nitrosamines, nitramines (nitroamines), imines, amides and nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) in the atmosphere are summarized and discussed. Sampling for the analysis of organic nitrogenous compounds was mostly conducted using high volume air sampler. The direct liquid extraction (DLE) using sonification and the pressurized liquid extraction (PLE) using the accelerated solvent extraction (ASE) have been frequently employed for the extraction of organic nitrogenous compounds in the atmospheric samples. After extraction, clean-up via filtration and the solid phase extraction (SPE) and concentrations using nitrogen and rotary evaporator have been generally conducted but in some studies the clean-up and concentration steps have been omitted to prevent the loss of analyte and improve the recovery rate of the analytical procedure. Instrumental analysis was mainly carried out using gas chromatography (GC) or the high performance liquid chromatography (HPLC) coupled with the single quadrupole mass spectrometer or tandem mass spectrometer in the electron ionization (EI), positive chemical ionization (PCI) and negative chemical ionization (NCI) mode and analysis sensitivity of nitrosamines and nitramines were higher in NCI mode. Desirable sampling and analysis methods for analyzing particulate organic nitrogenous compounds are suggested.

• Journal of the Korean Society for Heat Treatment
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• v.9 no.3
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• pp.219-227
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• 1996

The purpose of this research is to develop the technology for the synthesis of (Ti,Al)N powder, which shows simultaneously the excellent properties of TiN and AlN, from the Ti-Al intermetallic compounds by the direct nitriding method. The effects of variables such as temperature, Ti-Al intermetallic compounds ($TiAl_3$, TiAl and $Ti_3Al$) were investigated by TG, XRD and SEM. The (Ti,Al)N powder can be easily synthesized from the intermetallic compounds by the direct nitriding method. Among the intermetallic compounds, the nitriding behavior increased with TiAl> $Ti_3Al$ > $TiAl_3$, as the difference of diffusion coefficient for nitrogen in each materials. The ternary nitride such as $Ti_2AlN$ and $Ti_3Al_2N_2$ can be synthesized by the direct nitriding method, although the ternary nitride coexist with TiN and AlN. The ternary nitrides are stable below $1400^{\circ}C$, but these are gradually decomposed into TiN and AlN above $1400^{\circ}C$.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.203-206
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• 2006

The sensor consists of a heater, an insulating layer, a pair of contact electrodes, and CNT-sensing film on a micromachined diaphragm. The heater plays a role in the temperature change to modify sensor operation. Gas sensor responses of CNT-film to $NO_2$ at room temperature are reported. The sensor exhibits a reversible response with a time constant of a few minutes at thermal treatment temperature of $130^{\circ}C$.

• Korean Journal of Ecology and Environment
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• v.43 no.4
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• pp.453-458
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• 2010

DOC (Dissolved Organic Carbon) is an operational terminology for organic carbon molecules dissolved in natural waters. DOC has been studied by ecologists extensively, because it plays a key role in various ecological functions such as substrates for secondary production and the carbon cycle. DOC also represents a substrate for microbial growth within potable water distribution systems, and can react with disinfectants (e.g., chloride) to form harmful disinfection by-products. In addition, residual DOC may carry with it organically bound toxic heavy metals. DOC in aquatic ecosystems may ultimately be transported to the oceans, or released back to the atmosphere by heterotrophic respiration, which can accelerate global climate change. There is evidence that DOC concentrations in aquatic ecosystems are increasing in many regions of the world including Europe, North America, and even in Korea. Land use changes, elevated temperature, elevated $CO_2$, recovery from acidification, and nitrogen deposition have been proposed as mechanisms for the trend. However, the key driving mechanism is yet to be conclusively determined. We propose that more extensive and longer-term observations, research of chemical properties of DOC, impacts of elevated DOC on environmental issues and interdisciplinary approaches are warranted as future studies to fill the gaps in our knowledge about DOC dynamics.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.1
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• pp.32-37
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• 2006

In this study, we have purified and characterized the membrane bound nitrate reductase obtained from the denitrifying bacteria, Ochrobactrum anthropi SY509, which was isolated from soil samples. O. anthropi SY509 can grow in minimal medium using nitrate as a nitrogen source. We achieved an overall purification rate of 15-fold from the protein extracted from the membrane fraction, with a recovery of approximately 12% of activity. The enzyme exhibited its highest level of activity at pH 5.5, and the activity was increased up to $70^{\circ}C$. Periplasmic and cytochromic proteins, including nitrite and nitrous oxide reductase, were excluded during centrifugation and were verified using enzyme essay. Reduced methyl viologen was determined to be the most efficient electron donor among a variety of anionic and cationic dyestuffs, which could be also used as an electron donor with dimethyl dithionite. The effects of purification and storage conditions on the stability of enzyme were also investigated. The activity of the membranebound nitrate reductase was stably maintained for over 2 weeks in solution. To maintain the stability of enzyme, the cell was disrupted using sonication at low temperatures, and enzyme was extracted by hot water without any surfactant. The purified enzyme was stored in solution with no salt to prevent any significant losses in activity levels.

• Bulletin of the Korean Chemical Society
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• v.23 no.10
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• pp.1381-1391
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• 2002

The solvent sublation using ion pairs of metal-2-naphthoate(2-HNph) and tetrabutyl ammonium ($TBA^+$) ion has been studied for the concentration and determination of ultra trace Bi(III), In(III) and Tl(Ⅲ) ions in water samples. The partition coefficients ($K_p$) and the extraction percentages of 2-HNph and the ion pairs to methyl isobutyl ketone (MIBK) were obtained as basic data. After the ion pair $TBA^+$·M$(Nph)_4^-$ was formed in water samples, the analytes were concentrated by the solvent sublation and the elements were determined by GF-AAS. The pH of the sample solution, the amount of the ligand and counter ion added and stirring time were optimized for the efficient formation of the ion pair. The type and amount of optimum surfactant, bubbling time with nitrogen and the type of solvent were investigated for the solvent sublation as well. 10.0 mL of 0.1 M 2-HNph and 2.0 mL of 0.1 M $TBA^+$ were added to a 1.0 L sample solution at pH 5.0. After 2.0 mL of 0.2%(w/v) Triton X-100 was added, the ion pairs were extracted into 20.0 mL MIBK in a flotation cell by bubbling. The analytes were determined by a calibration curve method with measured absorbances in MIBK, and the recovery was 80-120%.

• Archives of Pharmacal Research
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• v.19 no.6
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• pp.475-479
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• 1996

Diethylcarbamazine (DEC, 1-diethylcarbamyl-4-methylpiperazine) is an antiparasitic piperazine derivative used in the treatment of lymphatic filariasis caused by Wuchereria bancrofti, Brugia malayi or grugia timori. DEC-N-oxide is a major metabolite in humans and has antifilarial activity. In carrying out pharmacokinetic studies, gas chromatographic analysis of DEC in plasma can be complicated by the presence of the metabolite, since the thermally unstable DEC-N-oxide is converted back to a material which coelutes with DEC under the conditions of the analysis. We now report a method to separate DEC-N-oxide from DEC in plasma using solid phase extraction with subsequent gas chromatographic analysis using a nitrogen specific detector. One-diethylcarbamyl-4-ethylpiperazine (E-DEC) was the internal standard. The standard curve of DEC was linear in the range of 10 to 200 ng/ml as described by Y=0.0350+0.0128X, $R^2=0.999$. The limit of quantitation was 4 ng/mL. Reproducibility at 10, 100 and 200 ng/mL concentration points of the standard curve gave coefficient variations of 6.1%, 7.8% and 1.6%, respectively. The recovery following solid phase extraction was 99.3% for DEC and 94.8% for the internal standard. This sensitive and specific analytical method is suitable for pharmacokinetic studies of DEC.

• Journal of Korean Society of Forest Science
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• v.95 no.5
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• pp.585-590
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• 2006

In vitro-grown axillary shot-tip meristems of Lycium chinense Mill. from cold-acclimated plant were successfully cryopreserved using a vitrification technique. After loading for 15 minutes with a mixture of 2.0 M glycerol and 0.4 M sucrose ($20^{\circ}C$), small segments (1-2 mm, 3-4 mm, and 5-6 mm) were cut from axilary buds and exposed to the cryoprotectant solution containing 30% glycerol, 15% ethylen glycol,15% dimethyl sulfoxide (DMSO), and 0.4 M sucrose at $0^{\circ}C$ for 30-120 minutes prior to direct plunge into liquid nitrogen (LN). After rapid thawing ($40^{\circ}C$), the segments were washed with MS medium containing 1.2 M sucrose for 0-35 minutes, and then transferred onto recovery-growth medium. The highest survival rate (about 90%) was obtained with cold-hardening treatment, and cryopreserved explants were successfully recovered to plantlets. No abnormal morphological changes were observed with the recovered plants after cryopreservation.

• Bulletin of the Korean Chemical Society
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• v.22 no.1
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• pp.19-24
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• 2001

A solvent sublation has been studied for the determination of trace Au(III), Pt(IV) and Pd(II) in waste water with their complexes of 2-mercaptobenzothiazole (MBT). Experimental conditions such as the concentration of HCl, the amount of MBT as a ligand, the type and amount of surfactants, bubbling rate and time, and the type of organic solvent were optimized for the solvent sublation, i.e., 25.0 mL of 2.0 M HCl solution and 30mL of 0.4%(w/v) MBT ethanolic solution were added to a 1.0 L sample to form stable complexes. The addition of 4.0 mL of 1 ${\times}$$10^{-3}$ M CTAB (cetyltrimehtylammonium bromide) solution was needed for the effective flotation accomplished by bubbling nitrogen gas at the rate of 40.0 mL/min for 35 minutes. As a solvent, 20.0 mL of MIBK (methylisobuthylketone) was used to extract the floated complexes. The procedure was applied to three kinds of waste waters. Au(III) was determined as 0.68 ng/mL and 0.98 ng/mL respectively for final washed water of two plating industries in Banwol. Pd(II) and Pt(IV) were not detected in any of the three samples. The recovery, which was obtained with analyte-spiked samples, were 95-120%.

• International Journal of Industrial Entomology and Biomaterials
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• v.39 no.1
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• pp.34-38
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• 2019

In this study, we investigated the effect of silkworm, and its by-products on exercise endurance, muscle mass, and fatigue recovery using ICR mice model. Powders of silkworm, pupae, dongchunghacho, and silk powder were suspended in water and feed to mice for 2 weeks. The forced swimming time was increased by 4.3, 4.1 and 2.8 seconds after silkworm, pupae, and dongchughacho administration compared to DW fed group. Increases in exercise ability were achieved by difference mechanism according to feeding materials. Pupae increased muscle mass by 129% compared with the control group which may effect on elongation of swimming time. Dongchunghacho improved the plasma concentrations of fatigue markers such as creatinine, blood urea nitrogen (BUN), and D-lactate. Silkworm administration showed dual effect, the muscle mass induction (114% vs. control) and anti-fatigue (plasma creatinine, BUN, and D-lactate were 63, 75, and 78% vs. con) effect which contributed most elongated swimming time. In conclusion, silkworm and its by-products including pupae and dongchunghacho with the predominant protein and bioactive components improved muscle mass and showed anti-fatigue effect which could promote exercise performance ability.