• Journal of Environmental Science International
• /
• v.4 no.3
• /
• pp.285-294
• /
• 1995

A comparative study on the chemical compositions of precipitations from February 1993 to April 1993 in Sungnam city of Kyunggi province, Inchon city, Kangneung city of Kangwon province, and Chongwon-gun of Chungbuk province has been performed. The metal cation and anion concentrations were measured by atomic absorption spectrometer and ion liquid chromatography, respectively. pH/Ion meter and direct nesslerization method were used for the concentration measurements of $H^+$ and $NH^{4+}$ ions, respectively. The quantitative orders of the cation and anion average concentrations, correlation coefficients between the ion concentrations, and pH values are used for chemical analysis on the environmental pollution and pollutant sources in the urban, surburban, seaside, and rural areas of the Korean Peninsula.

• Journal of Environmental Science International
• /
• v.7 no.2
• /
• pp.157-164
• /
• 1998

preliminary study on the chemical compositions of forty seven precipitations from March 1994 to May 1995 In Yeoncheon-gun, which Is adjacent to the southern boundary of demilitarized zone (DMZ) in the northernmost tip of Kyunggi Province has been Performed. The metal cation and anion concentrations were measured by atomic absorption spectrometer and ion chromatography, respectively. pH/lon meter and direct nesslerization method were used for the concentration measurements of $H^+$ ion and $NH_46+$ ions, respectively Based on the data, the quantitative orders of the cation and anion average concentrations were $Ca^{2+}>NH_4^+>Na^+>K^+>Mg^{2+}>H^+ and SO_4^{2+}>Cl^-> NO_3^-$, respectively..The ratio of average total anion concentration to average total cation concentration was 0.97. The average pH value of the precipitations was 5.60. These results, correlation coefficients between the ion concentrations, and monthly variations of pH value and precipitation amount are used for chemical analysis on the environmental Pollution and Pollutant sources In Yeoncheon-gun of Kyunggi province near DMZ.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.6
• /
• pp.905-912
• /
• 2019

Bioethanol has attracted much attention in recent decades as a sustainable and environmentally friendly alternative energy source. In this study, we compared the production of bioethanol by Candida molischiana and Saccharomyces cerevisiae at different initial concentrations of cellobiose and glucose. The results showed that C. molischiana can utilize both glucose and cellobiose, whereas S. cerevisiae can only utilize glucose. The ethanol yields were 43-51% from different initial concentrations of carbon source. In addition, different concentrations of microcrystalline cellulose (Avicel) were directly converted to ethanol by a combination of Trichoderma reesei and two yeasts. Cellulose was first hydrolyzed by a fully enzymatic saccharification process using T. reesei cellulases, and the reducing sugars and glucose produced during the process were further used as carbon source for bioethanol production by C. molischiana or S. cerevisiae. Sequential culture of T. reesei and two yeasts revealed that C. molischiana was more efficient for bioconversion of sugars to ethanol than S. cerevisiae. When 20 g/l Avicel was used as a carbon source, the maximum reducing sugar, glucose, and ethanol yields were 42%, 26%, and 20%, respectively. The maximum concentrations of reducing sugar, glucose, and ethanol were 10.9, 8.57, and 5.95 g/l, respectively, at 120 h by the combination of T. reesei and C. molischiana from 50 g/l Avicel.

• Toxicological Research
• /
• v.35 no.4
• /
• pp.295-301
• /
• 2019

In this review, we describe the absorption rates (Caco-2 cell permeability) and hepatic/plasma pharmacokinetics of 53 diverse chemicals estimated by modeling virtual oral administration in rats. To ensure that a broad range of chemical structures is present among the selected substances, the properties described by 196 chemical descriptors in a chemoinformatics tool were calculated for 50,000 randomly selected molecules in the original chemical space. To allow visualization, the resulting chemical space was projected onto a two-dimensional plane using generative topographic mapping. The calculated absorbance rates of the chemicals based on cell permeability studies were found to be inversely correlated to the no-observed-effect levels for hepatoxicity after oral administration, as obtained from the Hazard Evaluation Support System Integrated Platform in Japan (r = -0.88, p < 0.01, n = 27). The maximum plasma concentrations and the areas under the concentration-time curves (AUC) of a varied selection of chemicals were estimated using two different methods: simple one-compartment models (i.e., high-throughput toxicokinetic models) and simplified physiologically based pharmacokinetic (PBPK) modeling consisting of chemical receptor (gut), metabolizing (liver), and central (main) compartments. The results obtained from the two methods were consistent. Although the maximum concentrations and AUC values of the 53 chemicals roughly correlated in the liver and plasma, inconsistencies were apparent between empirically measured concentrations and the PBPK-modeled levels. The lowest-observed-effect levels and the virtual hepatic AUC values obtained using PBPK models were inversely correlated (r = -0.78, p < 0.05, n = 7). The present simplified PBPK models could estimate the relationships between hepatic/plasma concentrations and oral doses of general chemicals using both forward and reverse dosimetry. These methods are therefore valuable for estimating hepatotoxicity.

• Korean Journal of Animal Reproduction
• /
• v.27 no.2
• /
• pp.143-152
• /
• 2003

The objective of this study were to investigate the effects of Se and Vit. E administration on blood chemical values and Vit. E concentrations of serum in calves born from Hanwoo dams injected Se and Vit. E at late pregnancying periods. The effects of Se and Vit. E administration of blood chemical values in calves born from Hanwoo dams injected Se and Vit. E at the last month of pregnancying periods were examined. In albumin concentration of blood, the Vit. E 2000IU group were slightly higher than other groups and the cholesterol concentrations were also higher in Vit. E 15001u group than other groups. But, another components examined of blood chemical values were not significantly different in all experimental groups. The blood chemical values in calves born from Hanwoo dams administrated Se and Vit. E at two months before parturition were examined. However, there were not significantly different in all experimental groups in concentrations of albumin, cholesterol, BUN, creatinine, glucose, inorganic phosphorous, calcium, total protein and triglycerides. The concentrations of serum Vit. E in calves born from Hanwoo dams administrated Se and Vit. E at 30 and 15 days before parturition were examined. The concentrations of Vit. E in serum were higher in treatment groups than in control group(P>0.05). The concentrations of serum Vit. E in calves born from Hanwoo dams administrated Se and Vit. E at 60 days before parturition were examined, the concentrations of Vit. E in serum were slightly higher in groups administrated than in control group(P>0.05), but there were not significantly difference in all experimental groups.

• Journal of Environmental Health Sciences
• /
• v.20 no.2
• /
• pp.39-54
• /
• 1994

Dry and wet deposition samples were continuously collected by deposit gauge. In Bulkwang area of Seoul and Kanghwa in west coastal area of Korea. In order to evaluate the level of air pollution and its chemical composition, Bulkwang area located in Seoul and Kanghwa in west coastal area were chosen for sampling site. dry deposition concentrations, pH, electric conductivity and water soluble ion concentrations of deposit gauge were analysed. The results of comparison between urban area and coastal area were summarized as follows. Mean concentrations of dry deposition in Bulkwang was 2.807 ton/km$^2$/month (range: 5.171~1.128 ton/km$^2$/month) while that in Kanghwa was 1.990 ton/km$^2$/month (range: 3.358 ~ 1.084 ton/km$^2$/month), which showed a significant difference between two areas. The rainfall during the period from June to September in 1990 recorded 1859.7 mm which was 78.8% of its mean amount in Seoul, and 1846.9 mm which was 81.6% that of Kanghwa. In Bulkwang area, correlation coefficients of deposit chemical composition were 0.95 for SO$_4^{-2}$ and Na$^+$, 0.94 for SO$_4^{-2}$ and NH$_4^+$, 0.93 for CI$^-$ and NH$_4^+$ and 0.85 for Cl$^-$ and Ca$^{2+}$, respectively. Then, the results indicate that sulfates such as $Na_2SO_4$, $(NH_4)_2SO_4$, and CaSO$_4$ were the major chemical state of deposit. In Kanghwa area, it was considered that NaCl, $NH_4NO_3$, NaNO$_3$, and $Ca(NO_3)_2$ were the major chemical state of deposit.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.18 no.5
• /
• pp.37-48
• /
• 2015

Soil nutrient management is important to maintain the constant productivity of seedling production in the nursery for successful forest restoration. This study investigated the effects of organic manure and chemical fertilizer application levels on the growth, soil properties, and nutrient concentrations of yellow poplar seedlings. One-year-old yellow poplar seedlings were treated with the combination of 3 level organic manures(0, 5 Mg/ha, 10 Mg/ha; mixture of poultry manure, cattle manure, swine manure, and sawdust) and 3 level nitrogen-phosphorus-potassium(NPK) chemical fertilizers(0, 1x(urea, $30g/m^2$; fused superphosphate, $70g/m^2$; potassium chloride, $15g/m^2$), 2x). Organic manure significantly increased the soil pH and the concentrations of nitrogen, available phosphorous, exchangeable potassium, calcium, and magnesium. In contrast, the NPK chemical fertilizer decreased the soil pH and exchangeable calcium concentration, did not affect the soil concentrations of nitrogen and magnesium, and increased the concentrations of available phosphorous and exchangeable potassium. Both organic manure and NPK chemical fertilizer treatments increased the seedling height, root collar diameter, and dry weight by 39% and 25%, respectively. The treatment with manure 5 Mg/ha and NPK 2x chemical fertilizer mostly increased seedling dry weight by 2.6 times more than that of the control. Compared to the effects of the fertilization treatments on the soil properties, the effects on nutrient concentrations in the leaves were relatively small. These findings indicate that organic manure that was derived from livestock byproducts and sawdust can be utilized with chemical fertilizer to improve seedling production as well as conserving soil quality.

• Journal of Industrial Technology
• /
• v.25 no.A
• /
• pp.141-149
• /
• 2005

We investigated numerically the evolutions of several chemical species which are important for film growth and particle generation in the pulsed $SiH_4$ plasmas. During the plasma-on, the $SiH_x$ concentration increases with time mainly by the generation reaction from $SiH_4$, but, during the plasma-off, decreases because of the hydrogen adsorption reaction. During the plasma-on, the concentrations of negative ions increase with time by the polymerization reactions of negative ions and those become almost zero in the sheath regions because of the electrostatic repulsion. During the plasma-off, the concentrations of negative ions decrease with time by the neutralization reactions with positive ions and some negative ions can diffuse toward the sheath regions because there is no electric field inside the reactor. The polymerized negative ions of higher mass can be reduced successfully by using the pulsed plasma process.

• Bulletin of the Korean Chemical Society
• /
• v.17 no.10
• /
• pp.964-967
• /
• 1996

• Bulletin of the Korean Chemical Society
• /
• v.35 no.11
• /
• pp.3239-3243
• /
• 2014

We have developed a simple method for tuning the morphologies of $Cu_2O$ microcrystals. $Cu_2O$ microcrystals were prepared by precipitation at room temperature from a mixture of $Cu(CH_3COO)_2{\cdot}H_2O$, N,N,N',N'-tetramethyl ethylenediamine (TMEDA), ascorbic acid, and polyethylene glycol (PEG). TMEDA was used to promote the formation of copper-TMEDA complexes. A variety of $Cu_2O$ microcrystal morphologies were obtained simply by varying the concentrations of TMEDA and ascorbic acid. Aggregated $Cu_2O$ microspheres are formed at higher concentrations of ascorbic acid in the absence of TMEDA. Aggregated $Cu_2O$ microcubes are formed at lower concentrations of ascorbic acid and higher concentrations of TMEDA. The crystal growth mechanism of these $Cu_2O$ morphologies is explained.