• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.49-57
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• 2000

This study was carried out to find the optimal condition to treat refractory organic matter which can’t treat clearly with biological treatment and to find the optimal division dosage and division dose timing in the modification of Fenton oxidation which is used resolve the problem that hydrogen peroxide is too expensive. The results are following; 1. The highest TOC removal efficiency was 41% and color removal efficiency was 64% when the dilution magnitude of leachate is fold. This suggests that dilution is efficiency when high concentration of leachate is treated. 2. The removal efficiency of TOC and color increased up to the molar ratio between ferrate and hydrogen peroxide was 1:1. However above that ratio, removal efficiency hardly increased. The highest removal efficiency of TOC and color were 38% and 71% when the mole ratio of ferrate to hydrogen peroxide was 1.5:1. 3. When the mole ratio between ferrate and hydrogen peroxide was fixed, the removal efficiency of TOC and color increased as the dosage of hydrogen peroxide increased. 4. pH of samples were adjusted at pH 3, 5, 7, 9, 11. After oxidation reaction, pH of samples were dropped to 2.59, 2.54, 5.34, 6.36 and 9.68. The highest color removal efficiency was 75.7% when initial pH was at pH 7. 5. The removal of TOC and color was ended within 10. min. and the removal efficiency increased logarithmically within 10min. However after 10 min., the removal efficiency of hardly increased. 6. The color removal efficiency was higher with modification of fentone oxidation than that with fentone oxidation by 5%. Optimal division dosage ratio was 1:1 and optimal dose timing ratio was 2:1. However the TOC removal efficiency was not higher with modification of Fenton oxidation than that with Fenton oxidation.7. The CO $D_{Mn}$ /BO $D_{5}$ Ratio decreased with the time went by. It meant bioresolution increased as time went by. However, after 15 min., the CO $D_{Mn}$ /BO $D_{5}$ Ratio did not decrease any more. 8. In the case of $H_2O$$_2$ Divisiom Dose experiment, the increase of bioresolution was highest at the $H_2O$$_2$ Division dosage Ratio of 3:7.3:7.

• Korean Journal of Medicinal Crop Science
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• v.2 no.2
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• pp.162-167
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• 1994

This study was carried out to investigate the compositions of fatty acids, inorganic components and volatile organic acids from Korean valerian roots, Valeriana fauriei var. dasycarpa Hara and Valeriana officinalis var. latifolia Miq. The contents of total lipids ranged from 3.7 % to 4.5% and the major fatty acids were linoleic, linolenic and palmitic acid. Ash contents ranged from 4.3% to 6.3%. and the contents of Na, Fe, Zn and Cu showed some quantitative differences depending upon grown region or species. Fourty components were identified from acidic fraction of dichloromethane extract of V. fauriei var. dasycarpa Hara, of which the major components were 3-methyl butanoic, dimethoxy-2-propenoic. 3, 4-dimethoxy benzoic and 3-methyl pentanoic acid.

• Ocean and Polar Research
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• v.36 no.4
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• pp.407-421
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• 2014

The benthic environmental impact experiment addresses environmental impacts at a specific site related to deep-sea mineral resource development. We have acquired several tens of multi- or box core samples at 31 sites within the Benthic environmental Impact Site (BIS) since 2010, aiming to examine the basic properties of surficial deep-sea sediment as a potential source for deep-water plumes. In this study, we present the geochemical properties such as major elements, rare earth elements (REEs), and heavy metal contents at the BIS. Such proxies vary distinctly according to the Facies association. The lithology of all core sediments in the BIS corresponds to both Association Ib and Association IIIb. The vertical profiles of some major elements ($SiO_2$, $Fe_2O_3$, CaO, $P_2O_5$, MgO, MnO) show noticeable differences between Association Ib and IIIb, while others ($Al_2O_3$, $TiO_2$, $Na_2O$, and $K_2O$) do not vary between Association Ib and IIIb. REEs are also distinctly different for Associations Ib and IIIb; in Association Ib, REY and HREE/LREE are uniform through the sediment section, while they increase downward in Association IIIb like the major elements; below a depth of 8 cm, REY is over 500 ppm. The metal enrichment factor (EF) evaluates the anthropogenic influences of some metals (Cu, Ni, Pb, Zn, and Cd) in marine sediments. In both Associations, the EF for Cu is over 1.5, the EF for Ni and Pb ranges from 0.5 to 1.5, and the EF for Zn and Cd are less than 0.5, indicating Cu is enriched but Zn and Cd are relatively depleted in the BIS. The vertical variations of geochemical properties between Association Ib and IIIb are shown to be clearly different, which seems to be related to the global climate changes such as the shift of Intertropical convergence zone (ITCZ).

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.397-401
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• 2009

The complexes of $C_2-\;and\;C_6$-dihydroceramides with transition metal ions have been investigated by using Electrospray ionization-tandem mass spectrometry (ESI-MS/MS). The formation and fragmentation pathways of several doubly charged cluster ions as well as singly charged cluster ions of $C_2-\;and\;C_6$-dihydroceramides with transition metal ions have studied by ESI-MS/MS in the positive mode. Under ESI conditions, dihydroceramides form singly and doubly charged complexes with transition metal ions $(Mn^{2+},\;Fe^{2+},\;Co^{2+},\;Ni^{2+},\;and\;Zn^{2+}\;except\;Cu^{2+})$ with the compositions of $[DHCer+M+2H^2O-H]^+,\;[2DHCer+M+2H2O-H]^+,\;[3DHCer+M+2H2O-H]^+,\;[2DHCer+M]^{2+},\;[3DHCer+M]^{2+},\;[4DHCer+M]^{2+},\;[5DHCer+M]^{2+},\;and\;[6DHCer+M]^{2+}\;(DHCer\;=\;C_2-\;or\;C_6$-dihydroceramide, M = transition metal ion). The different complexation behavior of copper is responsible for relatively lower affinity of dihydroceramides to copper compared to those of other transition metals. It is also found that in the mass spectrum of the dihydroceramide complexes with copper(II), [2DHCer+Cu-H]$^+$ was observed with considerable intensity as well as [2DHCer+Cu+2$H_2O-H]^+$ due to its different geometry from those of other metals.

• Journal of Environmental Health Sciences
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• v.49 no.5
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• pp.251-261
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• 2023

Background: This paper deals with the study of natural radioactivity in rocks from Ogun State in Southwestern Nigeria. The aim is to determine radiation emissions from rocks in order to estimate radiation hazard indices. Objectives: The following objectives were targeted: 1. To determine radiation emissions from each type of rocks; 2. To estimate radiation hazard indices based on the rocks; 3. To correlate the activity concentrations of radionuclides with major oxides. Methods: The samples were analyzed using a NaI (Tl) gamma ray spectrometric detector and PerkinElmer AAnalyst 400 AAS spectrometer. Results: The activity of ⁴⁰K, ²²⁶Ra, and ²³²Th were found in order of decreasing magnitude from pegmatite>granite>migmatite. In contrast, lower concentrations were found in shale, phosphate, clay stone, sandstone and limestone. The mean absorbed doses were 125±23 nGyh^-1 (migmatite), 74±13 nGy/h (granite), 72±13 nGyh^-1 (pegmatite), 64±09 nGyh^-1 (quartzite), 45±16 nGyh^-1 (shale), 41±09 nGyh^-1 (limestone), 41±11 nGyh^-1 (clay stone), 24±03 nGyh^-1 (phosphate), and 21±10 nGyh^-1 (sandstone). The outdoor effective dose rates in all rock samples were slightly higher than the world average dose value of 0.34 mSvy^-1. The percentage composition of SiO₂ in the rock samples was above 50 wt% except for in the limestone, shale and phosphate. Al₂O₃ ranged from 4.10~21.24 wt%, Fe₂O₃ from 0.39~7.5 wt%, and CaO from 0.09-46.6 wt%. In addition, Na₂O and K₂O were present in at least 5 wt%. Other major oxides, including TiO₂, P₂O₅, K₂O, MnO, MgO and Na₂O were depleted. Conclusions: The findings suggest that Ogun State may be described as a region with elevated background radiation. It is recommended that houses should be constructed with good cross ventilation and residences should use home radiation monitoring instruments to monitor radon emanating from walls.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.436-447
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• 2004

Wetland plants have evolved specialized adaptations to survive in the low-oxygen conditions associated with prolonged flooding. The development of internal gas space by means of aerenchyma is crucial for wetland plants to transport $O_2$ from the atmosphere into the roots and rhizome. The formation of tissue with high porosity depends on the species and environmental condition, which can control the depth of root penetration and the duration of root tolerance in the flooded sediments. The oxygen in the internal gas space of plants can be delivered from the atmosphere to the root and rhizome by both passive molecular diffusion and convective throughflow. The release of $O_2$ from the roots supplies oxygen demand for root respiration, microbial respiration, and chemical oxidation processes and stimulates aerobic decomposition of organic matter. Another essential mechanism of wetland plants is downward water movement across the root zone induced by water uptake. Natural and constructed wetlands sediments have low hydraulic conductivity due to the relatively fine particle sizes in the litter layer and, therefore, negligible water movement. Under such condition, the water uptake by wetland plants creates a water potential difference in the rhizosphere which acts as a driving force to draw water and dissolved solutes into the sediments. A large number of anatomical, morphological and physiological studies have been conducted to investigate the specialized adaptations of wetland plants that enable them to tolerate water saturated environment and to support their biochemical activities. Despite this, there is little knowledge regarding how the combined effects of wetland plants influence the biogeochemistry of wetland sediments. A further investigation of how the Presence of plants and their growth cycle affects the biogeochemistry of sediments will be of particular importance to understand the role of wetland in the ecological environment.

• Journal of the Korean Ceramic Society
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• v.29 no.7
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• pp.577-585
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• 1992

TiB2 and TiC were prepared from the mixture of metal titanium, boron and graphite powders in Argon atmosphere by Self-propagating High-temperature Synthesis method. The sintered properties of TiB2-TiC composite as a function of TiC content and sintering temperature were investigated in TiB2 matrix. The sintered properties were the most excellent at 10 wt% TiC content in TiB2-TiC composite. The relative density, M.O.R strength, hardness and fracture toughness of TiB2-10 wt% TiC composite sintered at 190$0^{\circ}C$ for 90 min by hot-pressing under the pressure of 30 MPa were 98.6%, 634 MPa, 2128.1 kg/$\textrm{mm}^2$ and 4.09 MN/m3/2, respectively.

• Journal of Magnetics
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• v.6 no.4
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• pp.126-128
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• 2001

The effect of rapid thermal anneal (RTA) has been investigated on the properties of an FeMn exchange-biased magnetic tunnel junction (MTJ) using magnetoresistance and I-V measurements and transmission electron microscopy (TEM). The tunneling magnetoresistance (TMR) in an as-grown MTJ is found to be ∼27%, while the TMR in MTJs annealed by RTA increases with annealing temperature up to 300$\^{C}$, reaching ∼46%. A TEM image reveals a structural change in the interface of A1$_2$O$_3$layer for the MTJ annealed by RTA at 300$\^{C}$. The oxide barrier parameters are found to vary abruptly with annealing time within a few ten seconds. Our results demonstrate that the present RTA enhances the magnetoresistive properties of MTJs.

• Korean Membrane Journal
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• v.11 no.1
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• pp.15-20
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• 2009

The periodic water-back-flushing using permeate water was performed to minimize membrane fouling and to enhance permeate flux in tubular ceramic ultrafiltration (UF) system for Gongji stream water treatment in Chuncheon city. The filtration time (FT), which was the water-back-flushing period, 2 min with periodic 15 sec water-back-flushing showed the highest value of dimensionless permeate flux ($J/J_o$), and the lowest value of resistance of membrane fouling ($R_f$), and we acquired the highest total permeate volume ($V_T$) of 6.35 L. Consequently FT 2 min at back-flushing time (BT) 15 sec could be the optimal condition in advanced UF water treatment of Gongji stream. Then the average rejection rates of pollutants by our tubular ceramic UF system were 99.4% for Turbidity, 31.8% for $COD_{Mn}$, 22.6% for $NH_3$-N and 65.9% for T-P.

• Journal of Life Science
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• v.10 no.6
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• pp.577-583
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• 2000

This study was designed to investigate the effect of silk fibroin (Mw 500)power (SFP) on oxygen radicals and their scavenger enzymes in liver membranes of rats. Sprague-Dawley (SD) male rats (160$\pm$10 g) were fed basic diet (control group), and experimental diets (SFP-2.5 and SFP-5.0 groups) added 2.5 and 5.0 g/kg BW/day for 6 weeks. Hydroxyl radical (.OH) levels resulted in a considerable decreases (5.8% and 8.4%, 3.7% and 11.1%, respectively) in liver motochondria and micorsomes of SFP-2.5 and SFP-5.0 groups compared with control group, and $O_2$radical level was remarkably decreased about 15% and 20% in liver cytosol of SFP-2.5 and SFP-5.0 groups compared with control group. Lipid peroxide (LPO) levels were significantly decreased (8.3% and 18.0%, 13.4% and 18.4%, respectively) in liver mitochondria and microsomes of SFP-2.5 and SFP-5.0 groups compared with control group. Oxidized protein (OP) levels were remarkably decreased about 11.6% in liver mitochondria of SFP-5.0 group compared with control group. Mn-SOD activities were remarkably in creased (17.6% and 28.8%, respectively) in mitochondria of SFP-2.5 and SFP-5.0 groups, and Cu/Zn-SOD activities were also effectively in creased (about 14.4%) in liver cytosol of SFP-5.0 groups, but significant difference between GSHPx activity in liver cytosol of these two groups could be not obtained. These results suggest that anti-aging effect of silk fibroin may play an effective anti-aging role in a aattenuating a oxidative stress and increasing a scavenger enzyme activity in liver membranes.