• ALGAE
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• 제17권3호
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• pp.171-185
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• 2002

The standing crop of genus Microcystis, microcystin concentrations and environmental factors were monitored at stations of the lower reaches of the Nakdong River in 1998 and 1999 during the periods of its occurrence. The Microcystis were observed from May to Octorber, and the cell density was highest at Station Seonam up to 250,000 cells${\cdot}ml^{-1}$ forming scum over the water surface. There were signigicant relationships between the standing crop of Microcystis and nitrate nitrogen, total phosphorus concentrations and Ph. Presumably these parameters were important in the succession to Microcystis dominated phytoplankton community in the summer period in the river. However, Ammonium nitrogen, phosphate phosphorus concentrations and N/P ratio were not critical factors. The Microcystis bloom was notable above $25^{\circ}C$ of surface water temperature. Microcystins were detected from May to November in the algal materials from the river. The 84.2% of algal materials with Microcystis exhibited the microcystin with the maximum of 1711.8 ${\mu}g{\cdot}g^{-1}$ dw. The microcystin concentrations in the algal materials were significantly related to the stading crop of Microcystis, which was the primary determinant factor in the toxin levle of algal materials. The concentrations were also significantly related to pH of the water column in the positive pattern.

• Elastomers and Composites
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• 제51권3호
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• pp.240-249
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• 2016

$BiVO_4$ nanomaterial was synthesized from bismuth (III) nitrate pentahydrate [$Bi(NO_3)_3{\cdot}5H_2O$] and ammonium vanadate (V) [$NH_4VO_3$]. The $BiVO_4$-graphene nanocomposite was fabricated by calcining the $BiVO_4$ nanomaterial and graphene under an oxygen-free atmosphere at $700^{\circ}C$. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize structural and morphological properties of samples. The catalytic activity of the $BiVO_4$-graphene nanocomposite was studied for the reduction of 4-nitrophenol, 3-nitrophenol and 2-nitrophenol by sodium borohydride [$NaBH_4$]. The photocatalytic activity of the $BiVO_4$-graphene nanocomposite was demonstrated by the degradation of organic dyes like BG, MB, MO and RhB under irradiation at 365 nm. The catalytic and photocatalytic activity were studied by UV-vis spectrophotometry.

• Journal of Plant Biology
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• 제34권4호
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• pp.289-296
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• 1991

Cultures of hairy root induced from ginseng(Panax C.A. Meyer) transformed with Agrobacterium rhizogenes (strain A4, ATCC 15834) were established and morphologically two different hairy root strains (HB1, HB2) were obtained. To determine the optimum growth rate, the hairy root (HB2) was cultured in various liquid medium supplemented with or without plant growth hormone. The growth rate of hairy root cultured on MS medium was 1.3-3.1 times higher than those cultured on other media, and the optimum sucrose concentration and pH were 3-6%, 5.5-6.5, respectively. Also, the growth rate of hairy root was increased when 0.02 M ammonium nitrate, 1.2 mM potassium phosphate (monobasic) and 0.5 mg/l IBA were supplied to liquid medium. The saponin patterns and contents of hairy root (HB2) were determined by TLC and HPLC. The crude saponin contents were 4.67% and the total saponin contents were 1.0%, on dry weight basis.

• 한국해양학회지:바다
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• 제9권4호
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• pp.153-163
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• 2004

In order to estimate the nutrient flux of the Seomjin River into the coastal waters of South Sea, and to understand the estuarine reactions during mixing between river water and seawater, we collected surface water along the salinity gradient in the Seomjin River estuary from Mar. 1999 to Apr. 2001. We found that nitrate and silicate were delivered by fluvial input, while phosphate was, supplied from disposed wastes in the Gwangyang Bay. Mean annual flux of dissolved inorganic nitrogen (DIN), phosphate and silicate into the Gwangyang Bay was estimated 10.9 molesㆍsec$^{-1}$(4,820 tonnesㆍyr$^{-1}$), 0.07 molesㆍsec$^{-1}$(68 tonnesㆍyr$^{-1}$), 13.3 molesㆍsec$^{-1}$(11,747 tonnesㆍy$^{-1}$), respectively. An evident removal of phosphate, silicate and ammonium at the mid-salinity zone during the dry season was attributed to the active uptake of phytoplankton, and consequently nutrient flux into the Gwangyang Bay was low. Whereas, during the flood season in summer, conservative or additional distribution of the nutrients was observed in the estuary. As a rsult nutrient flux into the Gwangyang Bay was maintained high. High concentrations of chlorophyll a and the active removal of nutrient during the dry season at the mid-salinity zone suggest that nutrient distribution in the Seomjin River estuary was mainly controlled by biological processes and nutrient fluxes into the Gwangyang Bay might be significantly modified of by the primary production.

• Membrane and Water Treatment
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• 제8권6호
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• pp.517-528
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• 2017

This study evaluates the performance of membrane bioreactor (MBR) coupled with a modified walnut shell granular activated carbon (WSGAC) for tannery wastewater treatment. For this purpose, a pilot with overall volume of 80L and 12 hours hydraulic retention time (HRT) is operated in three scenarios. Here, the chemical oxidation demand (COD) of wastewater is reduced more than 98% in both C:N ratios of 13 (S1) and 6.5 (S2). This performance also remains intact when alkalinity depletes and pH reduces below 6 (S3). The ammonium removal ranges between 99% (S2) and 70% (S3). The reliability of system in different operating conditions is due to high solids retention time and larger flocs formation in MBR. The average breakthrough periods of WSGAC are determined between 15 minutes (S2) and 25 minutes (S1). In this period, the overall nitrate removal of MBR-WSGAC exceeds 95%. It is also realized that adding no chemicals for alkalinity stabilization and consequently pH reduction of MBR effluent (S3) can slightly lengthen the breakthrough from 15 to 20 minutes. Consequently, MBR can successfully remove the organic content of tannery wastewater even in adverse operational conditions and provide proper influent for WSGAC.

• Asian-Australasian Journal of Animal Sciences
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• 제24권3호
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• pp.439-448
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• 2011

Oxalic acid is synthesized by a wide range of plants. A few of them are forage plants that can cause oxalate poisoning in ruminants under certain conditions. In this paper, the role of some agronomic, climatic and genetic factors in minimizing oxalate accumulation in forage plants has been discussed. Research indicates that the content of oxalate in forage can be controlled by fertilizer application. For example, nitrate application resulted in higher contents of soluble and insoluble oxalates than ammonium application. With an increased rate of potassium application, soluble oxalate content showed an increasing trend and insoluble oxalate content showed a decreasing trend. With an increased rate of calcium application, soluble oxalate content showed a decreasing trend and insoluble oxalate content showed a reverse trend. Other agronomic factors such as growing season, harvesting practices, plant maturity, plant species, plant variety and plant parts can also have a large effect on oxalate accumulation. However, the potential benefits of the above approaches for improving forage quality have not been fully exploited. In addition, there is still insufficient information to fully utilize means (e.g. plant nutrients, season and soil moisture) to minimize oxalate accumulation in forage plants. Therefore, more research is required for a better understanding of the interactions between oxalate and the above-mentioned factors in forage plants.

• Journal of Microbiology
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• 제40권3호
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• pp.193-198
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• 2002

Several 2,4,6-trinitrotoluene (TNT) degrading bacteria were isolated from an activated sludge by an enrichment culture technique, and their TNT removal activities were examined. Among the isolates, strain C1 showed the highest degrading capability, and completely removed 100 or 200 mg I$\^$-1/ of TNT within 6 hours of incubation. This bacterium was identified as Klebsiella sp. The effects of different carbon sources on the removal of the parent TNT by Klebsiella sp. C1 were negligible, but the transformation rates of TNT metabolites such as amino-dinitrotoluenes and diamino-nitrotoluenes were higher with fructose addition compared to glucose addition. When nitrate was used as the nitrogen source, the degradation rates of TNT and hydroxylamino-dinitrotoluenes were higher than those with the ammonium addition. Although the TNT removal rate of Klebsiella sp. C1 was slightly higher in anaerobic conditions, the further transformations of TNT metabolites were more favorable in aerobic conditions.

• Journal of Korean Society for Atmospheric Environment
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• 제22권E1호
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• pp.27-34
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• 2006

Although the importance of size-resolved raindrops study has been known, it has not been popularized up to the present. In the present study, an attempt was made to generalize the size-resolved raindrops study by a combination of the frozen raindrop collection method and a commercially available high-performance capillary electrophoresis (HPCE). Samplings were carried out at Kyoto, Japan in October 2002. The inorganic ions (chloride, nitrate, sulphate, calcium, ammonium, sodium, magnesium, potassium) in size classified raindrop samples were successfully analyzed by HPCE with good repeatability. To assure the accuracy and precision of HPCE data, t-test was conducted with paired analytical data, which were experimentally constructed by analyzing standard solutions with HPCE and IC, respectively. T-test showed that there is no notable difference between the concentrations determined by the two analytical methods. Every ionic concentration in both cation and anion was found to be strong raindrop size dependence. Though there was slight increase of sodium and sulphate concentrations between 0.85 mm and 1.15 mm raindrop radius, it showed a strong decrease for every ionic component with increasing droplet radius. The combination of the frozen raindrop collection method and a commercially available HPCE can meet the need of size-resolved raindrops study.

• 한국환경농학회지
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• 제24권3호
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• pp.238-244
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• 2005

Fertilization effects on changes in soil $CO_2$ flux and organic C in switchgrass (Panicum virgatum L.) land managed for biomass production were investigated. The mean daily soil $CO_2$ flux in the manure treatment was 5.63 g $CO_2-C\;m^{-2}\;d^{-1}$, and this was significantly higher than the mean value of 3.36 g $CO_2-C\;m^{-2}\;d^{-1}$ in the control. The mean daily $CO_2$ fluxes in N and P fertilizer treatments plots were not different when compared to the value in the control plots. Potentially mineralizable C (PMC), soil microbial biomass C (SMBC), and particulate organic C (POC) were highest at the 0 to 10 cm depth of the manure treatment. Potentially mineralizable C had the strongest correlation with SMBC (r = 0.91) and POC (r = 0.84). There was also a strong correlation between SMBC and POC (r = 0.90). Our results indicated that for the N and P levels studied, fertilization had no impact on temporal changes in soil organic C, but manure application had a significant impact on temporal changes in soil $CO_2$ evolution and active C constituents such as PMC, SMBC, and POC.

• Mycobiology
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• 제36권1호
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• pp.28-33
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• 2008

Ganoderma lucidum (Fr.) Karst (Polyporaceae), belonging to basidiomycota, is one of the most famous medicinal mushrooms. This study was carried out to investigate favorable mycelial growth conditions, such as pH, temperature, growth media, carbon sources and nitrogen sources of Korean strains in G. lucidum. The most suitable temperature for the mycelial growth was obtained at $30^{\circ}C$. In general, optimal temperature range for the mycelial growth was found at $25{\sim}30^{\circ}C$. This Mushroom has a broad pH range ($5{\sim}9$) for its mycelial growth and mostly favorable growth was found at pH 5. Generally, Hamada, Glucose peptone, YM, Mushroom complete and Lilly media were the most suitable for the mycelial growth of G. lucidum. Among 10 different carbon sources, dextrin, galactose and fructose were best but the rest of other carbon sources also facilitated the growth of mycelia. The most suitable nitrogen sources were ammonium acetate, glycine, arginine and calcium nitrate, but to a certain extent, all of the supplemented nitrogen sources also stimulated the mycelial growth.