• Korean Journal of Veterinary Service
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• v.34 no.4
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• pp.429-439
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• 2011

This article described the comparison of a quick, easy, cheap, effective, rugged and safe (QuEChERS) sample preparation and the classical method established by National Veterinary Research and Quarantine Service (NVRQS) for the determination of pesticide residues in livestock products using GC-tandem mass spectrometry. The classical method by NVRQS used liquid-liquid partioning followed by evaporizing. The modified QuEChERS entailed extraction of 2 g sample with 15 ml acetonitrile containing 1% acetic acid followed by addition of 6 g anhydrous magnesium sulfate and 1.5 g sodium acetate. After centrifugation, 6 ml of the extract underwent a cleanup step (in a technique known as column-based solid phase extraction) using 400 mg each of $C_{18}$ and primary secondary amine sorbents plus 1,200 mg magnesium sulfate. The quantitation of individual pesticides by both methods was based on tissue standard calibration curves with a correlation coefficient in excess of 0.98 for the 24 pesticides. The detection limits by the classical method were ranged 1.3~5.0 ${\mu}g$/kg, with mean recoveries between 76.2% and 114.3% except aldrin (59.3%) and deltamethrin (63.6%). The detection limits by modified QuEChERS were ranged 0.3~6.2 ${\mu}g$/kg, with mean recoveries between 68.0% and 114.3% except dimethipin (152.6%), chlorfenvinphos (138.1%), 4,4-DDT (61.5%), aldrin (60.4%) and chinomethionate (30.3%).

• Journal of the Korean Wood Science and Technology
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• v.49 no.1
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• pp.44-56
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• 2021

The carbonized length and area of plywood by the various spreading concentration of water glass and the type of additives were measured in accordance with the 45° MecKel's burner method of the fire protection performance standard of the Korean National Fire Agency. As a result of treating water glass with a concentration of 20 to 50 % on plywood, the flame retardancy tended to increase in proportion to the concentration of water glass. However, the optimum concentration of water glass was determined to be 30 % due to the efflorescence and sticky on the surface of plywood treated with high-concentration water glass of more than 30 %. As a result of the experiment by adding different proportions of additives to the water glass with concentration of 30 %, the standard of flame performance standard was satisfied under the conditions with the addition of 15% potassium hydroxide and 1-10% aluminum hydroxide, respectively. On the other hand, there were no significant difference in the flame retardancy by adding magnesium sulfate. These results about the flame retardancy of plywood by water glass and additives were expected to be basic data for improving flame-retardant treated wood.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.2
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• pp.183-188
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• 1993

This experiment was conducted to investigate the effect of sulfur containing fertilizers on growth, yield and nutritive quality of soybean as affected by lime application at reclaimed soil. Lime application for neutralization requirements showed the effect of increased grain yield about 32% compared to the non application at newly opened land of red and yellow soil. In case of lime application, the sulfur containing fertilizers combined with super phosphate, ammonium sulfate, and gypsum increased the grain yield by 31%, 11%, and 3%, respectively. When lime was not applied, magnesium carbonate application increased the yield by 47%, super phosphate by 22%, and gypsum by 15%. The protein content of grain was higher at lime application than those of non lime application and was increased by the application of sulfur containing fertilizer. But lipid content was not affected by lime or sulfur application. From the above results obtained it was concluded that sulfur fertilizer effect under lime application was significant when combined with super phosphate or ammonium sulfate application. Magnesium carbonate or super phosphate application was the best combination with sulfur-containing fertilizer.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.3
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• pp.105-112
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• 2003

Effects of magnesium sulfate ($MgSO_4$) and magnesium hydroxide $[Mg(OH)_2]$, which have different chemical characteristics, on soil pH, electrical conductivity (EC), and exchangeable cation distributions were investigated. Using plastic columns packed with a loam soil, the two Mg-fertilizers were treated at the rate of $300kg\;MgO\;ha^{-1}$ and water was applied on the soil surface four times at every 7 days. Soil samples were taken at 5, 10, 15, and 20 cm depth after 7 days of each water application. Magnesium hydroxide could increase soil pH, but due to the low solubility of $Mg(OH)_2$, the effect on pH was limited on the surface soil. Soil pH was lowered in the $MgSO_4$ treatment and the effect was found through the 20 cm depth. Since the pH decrease in $MgSO_4$ treated soil was due to the salts from $MgSO_4$, after leaching of most salts from the investigated soil depth pH was not significantly different from that of non-treated soil. Soil EC was increased in $MgSO_4$ treatment through the soil depth, but in $Mg(OH)_2$ treatment EC was slightly increased only at the surface layer. Exchangeable Mg was increased in both of the treatments at surface layer after the first water application. In $Mg(OH)_2$ treatment, the increase of exchangeable Mg was found only at 5 cm depth through the experiment, but leaching down of Mg in the $MgSO_4$ treatment was very apparent. High concentration of Mg in the $MgSO_4$ treated soil could effectively replace exchangeable Ca through the investigated soil depth, but the effect of $Mg(OH)_2$ on exchangeable Ca was not significant.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2057-2064
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• 2014

Thermochemical sulfate reduction (TSR) was conducted in autoclave on the system of crude oil and $MgSO_4$ at different temperatures. Gas chromatography pulsed flame photometric detector (GC-PFPD) was used to detected the composition of organic sulfur compounds in oil phase products. The results of the analysis indicate that with increased temperature, the contents of organic sulfur compounds with high molecular weight and thermal stability, such as benzothiophenes and dibenzothiophenes, gradually became dominated. In order to gain greater insight into the formation and distribution of organic sulphur compounds from TSR, positive ion electrospray Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used in detecting the detailed elemental composition and distribution of them. The mass spectra showed that the mass range of sulfur compounds was 200-550 Da. Four sulfur class species, $S_1$, $N_1S_1$, $O_1S_1$ and $O_2S_1$, were assigned in the positive-ion spectrum. Among the identified sulfur compounds, the $S_1$ class species was dominant. The most abundant $S_1$ class species increase associated with the DBE value and carbon number increasing which also indicates the evolution of organic sulfur compounds in TSR is from the labile series to the stable one. In pure blank pyrolysis experiments with crude oil cracking without TSR, different composition and distribution of organic sulfur compounds in oil phase products were seen from mass spectra in order to evaluate their pyrolysis behaviors without $MgSO_4$. FT-IR and XRD were used in analyzing the products of solid phases. Two distinct crystallographic phases MgO and $MgSO_4$ are found to coexist in the products which demonstrated the transformation of inorganic sulfur compounds into organosulfur compounds exist in TSR.

• Journal of environmental and Sanitary engineering
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• v.8 no.1
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• pp.81-91
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• 1993

This paper was carried out to isolate and identify Aeromonas caviae which can degrade Sodium Dodecyl Benzene Sulfonate(SDBS) effectively. And the affecting factors for the ability of bacterial degradation were also studied. Frm October 1991 to February 1992, two hundred samples from sweage in Taegu area and Nakdong river waters in Talsung Gun area were tested. Minimal salt medium which contain SDBS only as a carbon source was used as a culture medium. The isolated new strain was identified as Aeromonas caviae Kim & Kweon. The optimal pH for SDBS degradation were 7.0 and temperature, $32^{\circ}C.$ It was taken 24 hours to degrade SDBS of 20mg/l completely under the optimal pH and temperature. And in the case of 30 mg/l of SDBS, it was taken 36 hours. The nitrogen sources were added to the minimal salt media containing 20mg/l of SDBS, and they were incubated at $32^{\circ}C$ for 14 hours. 86.9% SDBS were degraded after addition of 0.03% peptone as a organic nitrogen source. And 70.5% SDBS after addition of 0.05% ammonium sulfate as a inorganic nitrogen source. In the case of metal compounds(0.015%), the degradation rate for SDBS were 3.5 fold increased in the media containing magnesium chloride and calcium chloride than in the media that were not containing these metal compounds. And where the media containing magnesium chloride was 0.05%, the degradation rate was 65.8%. And above 0.3% NaCI, the degradation rate was decreased slowly.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.1
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• pp.39-44
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• 1989

This experiment was conducted to mature newly reclaimed upland and to increase soybean yield at this upland, Kim Jae, Jeon Buk, Koera from 1987 to 1988. Lime, lime-magnesium and calcium sulfate were applied with two, levels, amount of lime requirement, and 1.5 times of lime requirement. The results were summarized as follows: 1. The yields of soybean among treaments were in order of lime-magnesium 1.5 times, lime 1.5 times, lime-magnesium, calcium sulfate, lime and control with significancy at 1% level. 2. Correlations between yield components and inorganic element contents (T-N, $P_2O_5$, CaO and MgO) in plant at flowering stage were positive, but manganese in plant was negative at 5%, respectively. 3. Correlations, between yields and MgO and CaO contents in plant at flowering stage were positive, but Mn in plant was negative at 5% respectively. 4. Inorganic element contents of the soils at flowering stage were higher than those of before experiment. Correlation between yield and base saturation degree in soil at flowering stage was positive at 5%.

• Microbiology and Biotechnology Letters
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• v.7 no.2
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• pp.65-70
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• 1979

By the successive enrichment culture, methanol-utilizing bacteria of 213 strains were isolated from soil samples collected from various places. Among them one strain showing excellent growth was selected. The organism isolated was obligate methylotroph and identified as Methylomonas methanolica on the basis of its mophological and physiological characteristics of the cell. The medium have been to be collected for the maximum biomass productivity. The microorganism was capable of growing satisfactorily on a medium containing only methanol 0.8％ (v/v), ammonium sulfate 0.6％, magnesium sulfate 0.1％, phosphate salts, but did not require growth factor.

• KSBB Journal
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• v.26 no.6
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• pp.529-532
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• 2011

Whey based medium was optimized for the production of viable Lactobacillus crispatus KLB 46 isolated from the vagina of Korean women. Among the various nitrogen sources such as yeast extract, beef extract, and proteose peptone no. 3 supplemented to whey, beef extract showed the highest viable cell production. The addition of Tween 80 to the whey based medium increased viable cell concentration. As beef extract supplementation is not economically attractive, corn steep liquor was added as a supplementary nitrogen sources. When corn steep liquor was supplied with beef extract with the ratio 5 : 1, the viable cell count was $3.11{\times}10^9$ CFU/mL. Also, the addition of mineral salts containing sodium acetate (5 g/L), potassium phosphate dibasic (2 g/L), magnesium sulfate (0.1 g/L) and manganese sulfate (0.05 g/L) to the whey medium increased viable cell count further ($5.00{\times}10^9$ CFU/mL).

• The Korean Journal of Zoology
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• v.3 no.1
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• pp.9-12
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• 1960

The present status of insecticide resistance of Korean mosquitoes is still unknown. The experiment cited below is a part of our series of resistance tests on Korean mosquitoes. The test was carried out during the summer of 1959 to ascertain the degree of resistance of Culex pipiens to insecticides currently used. Culex pipiens eggs were collected from ditches in Seoul City and reared in laboratory with media consisted of the following : Distrilled water 1.0 liter, Magnesium sulfate (MgSO$_4$.7$H_2O$) 1.0gram , Calcium sulfate (CasO$_4$.2$H_2O$) 0.5gram ; Sodium cholride 0.5 gram. A Sufficient amount of beer yeast was also used as a larvar food. Late third and early fourth instar larvae were selected for testing. The results are summarized in the following. THe LC-50 of Culex pipiens to insecticides were 0.061 ppm in p, p-DDT , 0.045 ppm in ${\gamma}$-BHC and0.029 ppm in malathion. Comparing these with LC-50 doses of Orlando laboratory strain, it can be pointed out that the present resistance of Seoul strain shows about a ten-fold increase in DDt, and a fourfold increase in ${\gamma}$-BHC . The resistance development of the Seoul strain has, however, not arisen so markedly as compared with data observed in other parts of Far Eastern areas received heavy insecticidal operations.