• Journal of Environmental Health Sciences
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• v.37 no.1
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• pp.29-43
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• 2011

The seasonal characteristics of atmospheric particulate matter (PM) were evaluated through the measurement of $PM_{10}$ (particles with an aerodynamic diameter of less than 10 ${\mu}m$) and $PM_{2.5}$ (particles with an aerodynamic diameter of less than 2.5 ${\mu}m$) collected in the downtown area of Iksan city over roughly two weeks in each season of 2004. During the sampling period, 54 samples of $PM_{10}$ and $PM_{2.5}$ were collected and then measured for mass concentrations of PM and its water-soluble inorganic ion species. The concentrations of $PM_{10}$ and $PM_{2.5}$ were highly variable on a daily time scale in all seasons, especially in fall. Annual concentrations of $PM_{10}$ and $PM_{2.5}$ were $54.7{\pm}21.6\;{\mu}g/m^3$ and $34.0{\pm}13.4\;{\mu}g/m^3$, respectively. The daily concentrations of the analyzed ions similarly showed a pronounced variation, although a difference between seasons existed. Among them, $SO_4^{2-}$, $NO_3^-$ and $NH_4^+$ were the most abundant ions in all seasons, contributing up to 32% of $PM_{10}$ and 39% of $PM_{2.5}$. The contribution of $SO_4^{2-}$ and $NO_3^-$ showed a seasonal variation, as $SO_4^{2-}$ was the highest during spring and summer and $NO_3^-$ was the highest during fall and winter. Non-seasalt $SO_4^{2-}$ and $NO_3^-$ were found to exist mainly as neutralized chemical components of $(NH_4)_2SO_4$ and $NH_4NO_3$ due to the high concentration of $NH_4^+$ in PM samples, which were a major form of airborne PM in all seasons. Seasonal characteristics of $PM_{10}$ and $PM_{2.5}$ in Iksan were described in relation to the temporal variations of daily concentration of PM and its inorganic ion species including inter-particle reactions.

• Applied Biological Chemistry
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• v.24 no.2
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• pp.105-111
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• 1981

Growth responses of Brevibadterium ammoniagenes BA 17-2, which had been obtained by the treatment of several mutagens in our previous report, were investigated to select the preliminary optimal concentrations of phosphate, $Mg^{++}$, $Mn^{++}$ and thiamine for the production of 5'-XMP aminase. In this experiment it was shown that the concentration of phosphate in the medium has an important effect on the growth of microorganism. Using the medium containing 0.2% of $MgSO_4{\cdot}7H_2O$, 3mg/l of $MnSO_4{\cdot}H_2O$and $1\;mg/l$ of thiamine-HCl, the maximum cell mass was obtained at the concentration of 0.4% of $KH_2PO_4$ and $K_2HPO_4$, respectively. Above the concentration of these phosphates, cell growth was inhibited as the phosphate concentration increased to 1%, but the inhibition was overcome by the addition of 1% of $MgSO_4{\cdot}7H_2O$ and 3mg/l of thiamine-HCl. The 5'-XMP aminase activity was also influenced by the concentration of phosphate, $Mg^{++}$, $Mn^{++}$, and thiamine. In addition, the optimal culture pH and temperature for the enzyme activity were found to be 6.8 and $32^{\circ}C$, respectively.

• Journal of the Korean Applied Science and Technology
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• v.13 no.1
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• pp.67-74
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• 1996

This study was conducted to find a catalyst system which has high conversion and selectivity for the oxidative coupling of methane to produce ethane and ethylene. Various catalysts were tested in a fixed bed reactor ar $750^{\circ}C$, 1 atm, and the feed ratio($CH_4/O_2$) of 2/1. Under the reaction condition, 10wt%$PbSO_4/MgO$ catalyst showed the highest catalytic activity : methane conversion, $C_2$ selectivity and yield were 50, 40 and 20%, respectively. Catalysts containing sulfate compounds, 10wt%$PbSO_4/MgO$, 10wt%$MgSO_4/MgO$ and $Na_2SO_4/MgO$ revealed a moderate methane conversions such as 38, 50 and 50%, respectively and low $C_2$ selectivities such as 18, 5 and 9%, respectively. Catalysts containing carbonate compounds, 10wt%$PbCO_3/MgO$, 10wt%$Li_2CO_3/MgO$ and $NaCO_3/MgO$, also showed a moderate methane conversions such as 64, 44 and 51%, respectively and low $C_2$ selectivities such as 5, 6 and 2%, respectively. With the existence of chlorine and mercury, $C_2$ selectivity was decreased.

• Journal of the Korean institute of surface engineering
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• v.53 no.3
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• pp.87-94
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• 2020

Herein, sulfonated carbon nanotubes (CNT) have been prepared in dilute sulfuric acid (H₂SO₄) via a novel sulfonation approach based on gas-liquid interfacial plasma (GLIP) at room temperature. The sulfonic acid groups and total acid groups densities of CNT after GLIP treatment in 2 M H₂SO₄ for 45 min can reach to 0.53 mmol/g and 3.64 mmol/g, which is higher than that of sulfonated CNT prepared under 0.5 M / 1 M H₂SO₄. The plasma sulfonated CNT has been applied as catalysts for the conversion of microcrystalline cellulose to glucose. The effect of hydrolysis temperature and hydrolysis time on the conversion rate and product distribution have been discussed. It demonstrates that the total conversion rate of cellulose increasing with hydrolysis temperature and hydrolysis time. Furthermore, the GLIP sulfonated CNT prepared in 2 M H₂SO₄ for 45 min has shown high catalytic stability of 85.73 % after three cycle use.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.3
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• pp.305-315
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• 1999

The annular denuder system(ADS) was used to determine characteristics of acidic air pollutants and $PM_{2.5}$ species in Seoul-metropolitan areas. All measurements were done simultaneously in downtown(Kwanghwamun, Mullae, Chamshil, Ssangmun dongs) and outskirts(Puch n, Kuri cities) during four seasons. The samples were analyzed using ion chromatography for gas-phase matters(HCl, $HNO_2$, $HNO_3$ and $SO^2$) and particulate phase matters($Cl^-$, $NO^{2-}$, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $NH_4^-$ and $Ca^{2+}$) and was measured fine particles($PM_{2.5}$). The seasonal mean concentrations of HCl, HNO2, HNO3 and SO2 in downtown and outskirt areas were very similar. All chemical species monitored from this study showed seasonal variations. Nitric acid(HNO3) and Nitrous acid(HNO2) were showed higher concentrations during the summer. $PM_{2.5}$, $SO_4^{2-}$, $NH_4^-$, $NO_3^-$ and $Cl^-$ in the particulate phase matters were higher levels during the winter months. The concentrations of these components were 54.8, 3.82, 2.49, 1.80 and 1.02$\mu\textrm{g}$/㎥, respectively.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.454-458
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• 2007

The removal characteristics of ionic species, such as $Ca^{2+}$, $Mg^{2+}$, $Sr^{2+}$, $SO{_4}^{2-}$, $NO{_3}^-$, and $Cl^-$ by adsorption on the alumina were investigated. Alumina precusor powders were prepared from $Al(NO_3)_3{\cdot}9H_2O$ and $NH_4OH$. Alumina materials prepared from the heat treatment in a furnace at $450{\sim}750^{\circ}C$ for 5 h were analysed using FT-IR and the Brunauer-Emmett-Teller (BET) method. The specific surface area of the product particles decreased significantly with treatment temperature. The adsorption capacities of $SO{_4}^{2-}$and $NO{_3}^-$ on alumina were 23 mg/g and 12.4 mg/g, respectively. But, removal efficiencies of $Cl^-$ were less than 4 mg/g. In general, the removal efficiencies of the anion species were decreased with increasing treatment temperature. The best anion removal efficiency was obtained when the alumina was treated under $450^{\circ}C$. Removal efficiencies of $Ca^{2+}$, $Mg^{2+}$, and $Sr^{2+}$ were increased with increasing treatment temperature.

• Journal of Food Hygiene and Safety
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• v.38 no.3
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• pp.170-175
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• 2023

In this study, the effect of MnSO₄ on the insecticidal crystal (IC) produced by Bacillus thuringiensis for a rapid detection medium was analyzed. The strains used included one B. thuringiensis reference (KCTC 1511) and nine wild-type strains. The IC in B. thuringiensis was detected following the method published by the Ministry of Food and Drug Safety in Korea. In the nutrient agar to which 0.005% MnSO₄ was added, IC was observed on two of the three plates after 48 hours of incubation and on all three plates after 120 hours. In AK agar, IC was observed on one and two of the three plates after 48 and 96 hours of incubation, respectively. These results indicated that 0.005% MnSO₄ nutrient agar is more appropriate than AK agar for production of IC in B. thuringiensis. The effect of various MnSO₄ concentrations on IC production was studied after 24 hours of incubation. IC was produced on 1 of the 10 plates with 0.000% MnSO₄ nutrient agar, 2 of the 10 plates with 0.001% MnSO₄ nutrient agar, and 3 of the 10 plates with 0.002% MnSO₄ nutrient agar. IC was not observed for the other nutrient agars containing 0.003%-0.009% MnSO₄. These results indicated that nutrient agar with 0.002% MnSO₄ led to the most rapid production of IC by B. thuringiensis after 24 hours of incubation. However, the conditions for IC production by B. thuringiensis depended on the incubation conditions and strain activity. Therefore, further studies are needed to verify the effects of 0.002% MnSO₄ on the production of IC by various Bacillus thuringiensis strains.

• Journal of the Korean Ceramic Society
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• v.35 no.12
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• pp.1286-1293
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• 1998

${SO_4}^{2-}$ ions present in industrial waste water if combined with other metal ions in the water can cause serious scale problem in a transporting pipe. In this study therefore ${SO_4}^{2-}$ ions in an acidic solution have been removed by using surface active glasses. Glasses with various compositions of $SiO_2-Na_2O-B_2O_3-RO$ (R=Mg, Ca, Sr, Ba) system were reacted in a ${SO_4}^{2-}$ ion-containing solution with various pHs ranging from 1 to 4 for various time the reacted glass surfaces were analyzed by XRD and SEM and all ions in the reacted solution were also measured ${SO_4}^{2-}$ ions in the solution were combined with divalent ions leached out of glass and precipitated on the glass surface as sulfate crystals. In this was the surface ion could be removed from the acidic solution. The sulfate ion removal capacity is closely related to the solubility product con-stants of the newly formed sulfate crystals. Almost no sulfate crystal was formed on the MgO-containing glass while sulfate crystals were easily formed on the glass containing either SrO or BaO This indicates that those glasses have strong removal efficiency of ${SO_4}^{2-}$ ions from the solution.

• Korean Journal of Crystallography
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• v.16 no.2
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• pp.75-80
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• 2005

[ $LiK_{1-x}Rb_{x}SO_{4}(x=0.1,\;0.2)$ ] crystals were grown by means of aqueous solution growth technique at 313 K. Structure analysis of them was carried out with space group $P6_{3}(#173)$ by X-ray diffraction. In these compounds, the Li and $SO_{4}^{2-}$ ions lying on the three-fold axes formed infinite three-dimensional network and K and Rb atoms located on the six-fold axes are coordinated by twelve and fifteen O atoms respectively. The most suitable stabilization was achieved when the occupancy factors of K and Rb atoms are (0.91 : 0.09), (0.77 : 0.23) respectively.

• Journal of Life Science
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• v.12 no.2
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• pp.47-52
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• 2002

Saccharomyces cerevisiae KNU5377 (KNU5377) and S. cerevisiae ATCC24858 (ATCC24858) were exposed to $H_2SO_4$ as a stress, which was added at various concentrations to a YPD media. The growth of KNU5377 was reduced to approximately 60% in the YPD media containing 40 nm sulfuric acid when compared to the non-stressed condition. When their growth was monitored during an overnight culture, two strains, KNU5377 and ATCC24858, could not grow when exposed to over 50 mM of sulfuric acid. After a short exposure to this acid for 1 h, KNU5377 exhibited stronger resistance against $H_2SO_4$ than ATCC24858. The neutral trehalase activity of KNU5377 unchanged despite under various concentrations of $H_2SO_4$. In contrast, It at of ATCC24858 was much low at higher $H_2SO_4$concentrations. Trehalose, a non-reducing disaccharide, was maximally accumulated after a short exposure to 60 nm $H_2SO_4$ for KNU5377, but it was reduced under more severe stressful conditions. These results suggest that KNU5377 should modulate the trehalose concentrations under the severe stress condition of high sulfuric acid concentrations. The most highly induced protein in the KNU5377 exposed to sulfuric acid was found to be an approximately 23 kDa protein, which was revealed to be the 605 large subunit ribosomal protein, Ll3 by FASTA search results.