• Microbiology and Biotechnology Letters
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• v.26 no.2
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• pp.96-101
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• 1998

Respiratory denitrification experiments were performed using different carbon sources (acetic acid, glucose, methanol, molasses). In the culture media with glucose and molasses, COD consumption and denitrification rates were higher than with acetic acid and methanol. However, up to 30-40% of reduced nitrate and nitrite were converted to ammonium in glucose and molasses media. In the culture media with acetic acid and methanol, ammonium was not accumulated. Some of the consumed COD seemed to be used by the acid formers for the acidification in glucose and molasses media. By initial pH control of with molasses media, higher denitrification rate (up to 99%) and faster response could be obtained.

• Korean Journal of Materials Research
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• v.11 no.11
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• pp.953-959
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• 2001

Homogeneous spherical W-Co salt powders were made by spray drying of aqueous solution of ammonium $metatungstate(NH_4)_6(H_2W_{12}O_{40}){\cdot}4H_2O,\; AMT)$ and cobalt nitrate $hexahydrate(Co(NO_3)_2{\cdot}6H_2O)$. The thermal decomposition process of spray dried W-Co salt powders was studied by TG, XRD, SEM, TEM and FT-IR. Spray dried W-Co salt powders were calcined for 1 hour in the temperature from$ 350^{\circ}C$ to $800^{\circ}C$ in atmosphere of air. At the temperatures over $600^{\circ}C$, spherical $CoWO_4/WO_3$ composite oxide powders were obtained. The primary particle size of W/Co composite oxide powders increased with increasing thermal decomposition temperature due to the particle growth. The observed crystallite size by TEM was in the range of 60nm and that of $CoWO_4$ calculated by Scherrer's formula at $800^{\circ}C$ was smaller than 55nm. The crystallite site was identified by XRD and TEM.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3659-3664
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• 2013

Eight representative explosives (ammonium perchlorate (AP), ammonium nitrate (AN), trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), cyclonite (RDX), cyclotetramethylenetetranitramine (HMX), pentaerythritol tetranitrate (PETN), and hexanitrostilbene (HNS)) were comprehensively analyzed with an ion trap mass spectrometer in negative ion mode using direct infusion electrospray ionization. MS/MS experiments were performed to generate fragment ions from the major parent ion of each explosive. Explosives in salt forms such as AP or AN provided cluster parent ions with their own anions. Explosives with an aromatic ring were observed as either $[M-H]^-$ for TNT and DNT or $[M]^{{\cdot}-}$ for HNS, while explosives without an aromatic ring such as RDX, HMX, and PETN were detected as an adduct ion with a formate anion, i.e., $[M+HCOO]^-$. These findings provide a guideline for the rapid and accurate detection of explosives once portable MS instruments become more readily available.

• Journal of Environmental Health Sciences
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• v.16 no.2
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• pp.31-39
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• 1990

An analytical method for particulate carbon and other elements by using elemental analyzer was investigated. Carbon, hydrogen, and nitrogen was determined as CO$_{2}$, H$_{2}$, and N$_{2}$, respectively. Organic was determined after scparation from elemental carbon(Cae) by volatilization and thermal decomposition in a heated helium flow. With organic materials examined in this reprot, more than 90% of carbon was detected as above 600$^{\circ}$C. But it is considered that a few percents of some compounds were charred above 550$^{\circ}$C. A small amount of Cae was oxidized in the inert atmosphere above 850$^{\circ}$C, but the reason was not explained clearly. Based on the thermal chracteristics of Cao it was found that the optimum temperature of heating in the helium flow of an elemental analyzer for Cao analysis is 630$^{\circ}$C. Carbon in a sample after removing Cao was assumed as Cae and the gramatom ratio of hydrogen to carbon in the sample was 0.4 and less. Rescovery of nitrogen derived from some ammonium salts and nitrates was 100% by two-step measurement with elemental analyzer. By the analytical method investigated in this report, carbon and other elements in suspended particulates(S.P) collected at an urban area in Seoul were measured. There was a good correlation between total nitrogen in SP measured by elemental analyzer and nitrogen estimated form ammonium ions and nitrate ions in SP. The nitrogen from these ions accounts for 80% of the total nitrogen. It is further suggested that the residue(20%) of the total nitrogen is attributed to the other nitrogeneous compounds.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.E1
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• pp.24-31
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• 2008

In this study, a new PM (particulate matter) sampler was developed and fabricated to collect fine particles in the atmosphere, and laboratory and field tests were carried out to evaluate the performance of the sampler. The PM sampler, which was based on impingers, employed an aerosol condensation system as a PM magnifier to improve its collection efficiencies. Sodium chloride, ammonium sulfate and ammonium nitrate aerosols were used as test particles, because these components are rich in ambient aerosols. As a result, it was found that the collection efficiency of the novel PM sampler was very high. Thus, it is believed that the PM sampler is an effective device for sampling fine particles. In addition, it was demonstrated that this work could contribute to the collection or removal of fine particles and be applied to the semicontinuous sampling of ambient aerosols for chemical composition analysis.

• Journal of the Korean Chemical Society
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• v.52 no.1
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• pp.66-72
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• 2008

The photocatalytic degradation of a textile diazo dye in aqueous solution has been investigated under Solar and UV-A light. The effect of various parameters such as concentration of dye, amount of catalyst and pH on the degradation of dye has been studied. Addition of hydrogen peroxide, ammonium persulphate and isopropanol strongly influences the degradation rate. Kinetic analysis of photodegradation reveals that the degradation follows approximately pseudo first order kinetics according to the Langmuir-Hinshelwood model. Carbon dioxide, nitrate and sulphate ions have been identified as mineralisation products. The photocatalyst ZnO was found to be more efficient in UV-A light than in Solar light.

• Korean Journal of Microbiology
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• v.11 no.3
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• pp.121-128
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• 1973

In order to clarify the best cultural conditions of Rhizopus niveus the effects of aeration, pH and various nutrients, such as different carbon and nitrogen sources, vitamins, and growth substances, on the mycelial growth were studied through liquid culture, and amylase activities of the fungus at different cultural periods were measured. Soluble starch, xylose and galactose are excellent sources of carbon for growth of the fungus. Sorbose and lactose are utilized slightly for growth. peptone, ammonium sulfate and alanine are excellent nitrogen sources for growth, tyrptophane nad potassium nitrate are utilized slightly for growth and sodium nitrite is not utilized. Thiamine nad gibberellin are excellent growth substances for the fungal growth, and biotin, nicotinamide and indole acetic acid (IAA) are also effective. Rhizopus niveus grows better at rotatory culture than at stationary culture and earlier growth of the fungus increases remarkably at rotatory culture. Optimum pH than at pH3. Growth increases linerly with an increase of soluble starch content up to 100g per liter medium, but 5 grams of ammonium sulfate per liter is the optimum nitrogen concentration for growth, if Pfeffer's medium is employed. Amylase activities of Rhizopus at different cultural periods showed that the maximum amylase production takes place after the cell population has reached its peak in the culture. Dextrinogenic amylase production has reached maximum at stationary phase, and maximum saccharogenic maylase production takes place in the pahse of negative gorwth acceleration.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.689-695
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• 2003

Electrochemical decontamination process has been applied for recycle or self disposal with authorization of large amount of metallic wastes contaminated with uranium compounds such as $UO_2$, ammonium uranyl carbonate (AUC), ammonium di-uranate (ADU), and uranyl nitrate(UN) with tributylphosphate(TBP) and dodecane, which are generated by dismantling the contaminated system components and equipment of a retired uranium conversion plant in Korea Atomic Energy Research Institute (KAERI). Electrochemical decontamination for metallic wastes contaminated with uranium compounds was evaluated through the experiments on the electrolytic dissolution of stainless steel as the material of the system components in neutral salt electrolytes. The effects of type of neutral salt as the electrolyte, current density, and concentration of electrolyte on the dissolution of the materials were evaluated. Decontamination performance tests using the specimens taken from a uranium conversion plant were quite successful with the application electrochemical decontamination conditions obtained through the basic studies on the electrolytic dissolution of structural material of the system components.

• Journal of Integrative Natural Science
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• v.4 no.2
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• pp.103-112
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• 2011

This study was carried out on 4 batch reactors to determine the specific ammonium oxidizing rate (SAOR), specific nitrate forming rate (SNFR) and inhibitory degree of nitrifying activities with saline concentrations. Under salt free condition ammonia was consumed during the reaction period within 200 min. When the salt level increased to 10, 20 and 30 g $NaClL^{-1}$ in reactor, ammonia depletion took 250, 300 and above 350 min, respectively. During concentration above 10 g $NaClL^{-1}$, there was nitrite accumulation. Also, at 30 g $NaClL^{-1}$ ammonia did not depleted and $NO_2{^-}$-N accumulated until the final reaction. Nitrate formation rates decreased with increasing salt concentration. SAOR and SNFR showed a decreasing trend as salinity concentrations were increased. The SAOR was reduced from 0.2 to 0.08 mg $NH_4{^+}$-N $g^{-1}VSS\;day^{-1}$ as the salt concentration increased from 0 to 30 g $NaClL^{-1}$. Similarly, the SNFR decreased from 0.26 kg $NO_3{^-}$-N $kg^{-1}VSS\;day^{-1}$ at saline free to 0.1 kg $NO_3{^-}$-N $kg^{-1}VSS\;day^{-1}$ at saline 30 g L-1. A severe inhibition of nitrifiers activity was observed at increased salt concentrations. The inhibition ratio of specific ammonium oxidation rates were 17, 47 and 60% on the reactor of 10, 20 and 30 g $NaClL^{-1}$ added, respectively. The inhibition ratio of specific nitrate forming rates also were inhibited 30, 53 and 62% on the reactor of 10, 20 and 30 g $NaClL^{-1}$ added, respectively. As the salinity concentrations increased from 0 to 30 mg $NaClL^{-1}$, the average MLSS concentration increased from 1,245 to 1,735 $mgL^{-1}$. The SS concentration of supernatant in reactor which settled about 30 minutes was not severely difference between concentration of salt free reactor and one of those high salt contained reactors.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.3
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• pp.307-317
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• 2019

To develop sustainable new natural anti-aging ingredients from Korean native plants, we investigated the cultivation potential of Nymphoides indica using the eco-friendly aquaponics system, and tested the anti-aging effects from N. indica extracts. N. indica could be grown in aquaponics system using floating leaved deep water culture method, and propagated through rhizome propagation. It was confirmed that the nitrate ($80{\mu}g/mL$), potassium ($63.5{\mu}g/mL$) and water temperature ($25^{\circ}C$) greatly affected the cultivation of the N. indica. In addition, synergistic effects were found when two major components (3,7-di-O-methylquercetin-4'-O-${\beta}$-glucoside & sweroside) were present at more than about $5{\mu}g/mL$. The extract had a significant effect on the recovery of skin cells damaged by environmental pollutant such as $benzo[{\alpha}]pyrene$, ammonium nitrate, formaldehyde. It also suppressed $PGE_2$, $TNF-{\alpha}$ and COX-2, and inhibited the production of MMP-1. Taken together, the results suggested that the standardized extracts of N. indica cultivated in the aquaponics has considerable potential as a new cosmetics ingredient with an anti-aging effect.