• Clean Technology
• /
• v.11 no.3
• /
• pp.123-128
• /
• 2005

Among various metal oxides semiconductors, $TiO_2$ is the most studied semiconductor for environmental clean-up applications due to its unique ability in photocatalyzing various organic contaminants, its chemical inertness, and nontoxicity. $TiO_2$, however, has a few drawbacks to be solved such as reactivity mainly working under ultraviolet irradiation (${\lambda}$ < 387 nm) and electron - hole recombination on $TiO_2$. In this study, to extend the absorption range of $TiO_2$ into the visible range and enhance electron - hole separation, we synthesized platinum (Pt) deposited $C-TiO_2$. The presence of Pt as an electron sink has been known to snhance the separation of photogenerated electron-hole pairs and induce the thermal decomposition. The characterization of as-synthesized $Pt-C-TiO_2$ was performed by Transmission Electron Microscopic (TEM), the Brunuer-Emmett-Teller (BET) method, X-ray Diffractometer (XRD), UV-vis spectrometer (UV-DRS), and X-ray Photoelectron Spectroscopy (XPS). In order to estimate the photocatalytic activity of the synthesized materials, the photoelectron Spectroscopy (XPS). In order to estimate the photocatalytic activity of the synthesized materials, the photodegradation experiment of an azo dye (Acid Red 44; $C_{10}H_7N=NC_{10}H_3(SO_3Na)_2OH$)was carried out by using an Xe arc lamp (300 W, Oriel). A 420 nm cut-off filter was used for visible light irradiation. From the results, Pt-deposited $C-TiO_2$ showed a far superior phothdegradation activity to Degussa P25, the commercial product under the irradiation of visible light and enhanced photocatalytic activity of visible-working $C-TiO_2$. This is a useful result into the application for the purification system of dye wastewater using visible energy of sun light.

• Korean Journal of Ecology and Environment
• /
• v.35 no.1 s.97
• /
• pp.10-20
• /
• 2002

Changes of seasonal and vertical water quality was analyzed with physico-chemical data from Soyang and Paldang river-reservoir system in Korea during the 1996 to 1998. In Soyang river-reservoir system, the water column was well stratified, which narrow epilimnion layer of 5 to 10 m depth in spring to summer enlarged gradually about 40 m depth in fall as going to times. In contrast, metalimnion layer tended to be narrow during the same period. Water temperature of hypolimnion was maintained about $5^{\circ}C$ continuously throughout the year. DO of the epilimnion layer was supersaturated from spring to summer, however, it was decreased to 75% at the epilimnion layer and $45{\sim}50%$ at the hypolimnion layer at the late fall. The lowest conductivity of below $50\;{\mu}S/cm$ was observed at the metalimnion layer during thesummer to fall. In Paldang river-reservoir system, the water column wag well mixed layer throughout the year, although water temperature was changed seasonally from $5^{\circ}C$ in February to $28^{\circ}C$ in July. Water temperature between upper and lower layer was different about $5^{\circ}C$ from late spring (May) to early fall (September). DO was over and less saturated in upper and lower layer during the early summer to early fall, respectively. Conductivity was decreased to $90\;{\mu}S/cm$ in lower layer of below $4{\sim}5\;m$ depth during the late spring to early fall and that of upper layer of above 10 m depth decreased to about $100\;{\mu}S/cm$ during the late fall (November) and early spring (March). Retention time of Soyang river-reservoir system was much longer than that of Paldang river-reservoir system. Chlorophyll a, T-N and T-P concentration in Paldang river-reservoir system were higher than that of Soyang river-reservoir system by a factor of 2.7, 1.2 and 2.6, respectively. Algal blooming was deeply affected by the nutrients than the retention time.

• Korean Journal of Ecology and Environment
• /
• v.33 no.4 s.92
• /
• pp.366-373
• /
• 2000

Toxin production and low digestibility of cyanobacteria are known to cause low exploitability of cyanobacteria by zooplankton. In this study, we compared relative tolerance and compatibility of zooplankton taxa in eight eutrophic lakes, exposed to frequent cyanobacterial blooms, uring the summer season of 1999. Microcystis, Anabaena, Oscillatoria and Phormidium were common cyanobacteria in all lakes. with relatively lower $NO_3-N$ concentration (<0.2 mgN/l) and TN/TP ratio (<20), compared with other lakes where colonial cyanobacteria dominated. Rotifers were dominant zooplankton in most lakes, and among them, Keratella, Polyarthra and Hexathra were common. The laboratory feeding experiment showed that relative copepods that greatly decreased (90%) after 4 day when cyanobacteria were used as the food source of zooplankton, while rotifers gradually increased with the change of dominant taxa from Keratella through Pompholyx to Monostyla. These results suggest that rotifers may be capable of coexisting with cyanobacteria by exploiting them for the food source.

• Korean Journal of Environmental Biology
• /
• v.31 no.1
• /
• pp.19-36
• /
• 2013

Physiochemical characters of sea waters during summer flood- and winter dry-seasons and their spatial variations were investigated along the coastal area off the eastern South Sea, Korea. Using the hierarchical clustering method, in this study, we present comprehensive analyses of coastal waters masses and their seasonal variations. The results revealed that the coastal water of the study area was classified into six water masses (A to F). During summer season, the surface water was mainly occupied by the coastal pseudo-estuarine water (water mass B) with low salinity and high nutrients and the river-dominated coastal water (water mass C) with low nutrients, respectively. The bottom water was dominated by cold water (water mass D) with very low temperature, high salinity and high nutrients, compared to masses of surface water. Notably, the water mass B, with high concentrations of nutrients (silicate and nitrogen) and low salinity, which is strongly controlled by the water quality of river freshwater, seems to play an important role in controlling the water quality and further regulating physical processes on ecosystem in the eastern coastal area of South Sea. The water mass D (bottom cold water) coupled with a strong thermocline, which exists in near-bottom layer along the western margin of Korea Strait, has a low temperature, pH and DO, but abundant nutrients. This water mass disappears in winter owing to strong vertical mixing, and subsequently may act as a pool for nutrients during winter dry-season. On the other hand, vertically well-mixed water column during the winter season was typically occupied by the Tsushima (water mass E) and the coastal water (water mass F) with a development of coastal front formed in a transition zone between them. These winter water masses were characterized by low nutrient concentration and balance in N/P ratio, compared with summer season with high nutrient concentrations and strong N-limitation. Accordingly, the analysis of water masses will help one to better chemical and biological processes in coastal area. In most of the study area, characteristically, the growth of phytoplankton community is limited by nitrogen, which is clearly different with coastal environment of West Sea of Korea, with a relative lack of phosphorus. It showed the western and the southern coasts in Korea are substantially different from each other in environmental and ecological characteristics.

• Childhood Kidney Diseases
• /
• v.11 no.1
• /
• pp.9-15
• /
• 2007

Purpose : Edema is one of the cardinal features of nephrotic syndrome. Although the pathogenesis of edema is not entirely understood, it is caused by hypovolemia or hypervolemia by different mechanisms. Accordingly it is important to evaluate the volume status of patients in order to treat the edema, but it is difficult to evaluate the patient's volume status only by clinical parameters. The quotient of urine sodium and potassium excretion $U_K/(U_{Na}+U_K)$ is introduced as a more useful way to evaluate volume status. In this study we will propose the usefulness of $U_K/(U_{Na}+U_K)$ in evaluating the volume status of children with nephrotic syndrome. Methods : Primary nephrotic syndrome patients at Yeungnam University Hospital since January 1995 to June 2005, were included in the study. We analyzed clinical parameters such as tachycardia, cardiomegaly, pleural effusion, blood chemistry and urinalysis prospectively. We defined hypovolemia when $U_K/(U_{Na}+U_K)$ exceeded 60%. Intravenous albumin and diuretics were administered to hypovolemic edematous patients. On the other hand, hypervolemic edematous patients were treated only with diuretics. Results : There were 50 cases of primary nephrotic syndrome patients(hypervolemia: 29 vs hypovolemia: 21). There were no significant differences in clinical symptoms and laboratory findings except for FeNa While $F_eNa$ and $U_K/(U_{Na}+U_K)$ had a significant negative correlation, BUN and $U_K/(U_{Na}+U_K)$ had a significant positive correlation. Urine output after edema treatment was effective and there were no treatment-related side effects in both groups. Conclusion : FeNa, BUN and $U_K/(U_{Na}+U_K)$ are a useful parameters for evaluating volume status of edematous nephrotic syndrome patients. We could suggest a therapeutic option for using albumin and/or diuretics according to volemic status by means of measured $U_K/(U_{Na}+UK)$.

• Korean Journal of Poultry Science
• /
• v.18 no.1
• /
• pp.43-55
• /
• 1991

This experiment was conducted to study the sparing effects of animal proteins on weight gain, nutrients utilizability and economic analysis of broiler. Experiment diet contained different ratio of animal and plant protein and were supplemented different levels of methionine and lysine for the respective protein levels. A total of 264 broiler chicks were fed four diets of control, $T_1$, $T_2$ and $T_3$ for 42 days from April 7, 1990 to May 19, 1990. Dietary protein levels of control, $T_1$, $T_2$ and $T_3$ for starter and finisher were 20~18, 18~16, 18~16 and 22~20%, respectively. Methionine and lysine levels of control, $T_1$, $T_2$ and $T_3$ were 0.4~1.1, 0.44~1.21, 0.48~1.32 and 0.48~1.32% for starter diet, respectively, and were 0.32~0.90. 0.35~0.99, 0.38~1.08 and 0.38~1.08% for finisher diet, respectively. The results obtained were summarized as follows. 1. The birds fed control diet gained most for overall period. $T_3$ treatment which was high in protein, methionine and lysine levels gained most for finisher period. 2 The birds fed control diet consumed most feed, and the birds fed T$_3$ diet consumed least feed. for overall period. Feed conversion during 1~4 weeks was better in $T_1$ (1.51) and $T_2$ (1.53) than in control (1.61) and $T_3$ (1.63) . During 4~6weeks, feed conversion was better in $T_3$ (1.37) and control(1.58) than T, (2.05) and T, (2.16) (P＜0.01) 3. Dry matter, crude fiber and NFE utilizability were increased for 1~4 weeks and decreased for 4~6 weeks as methionine and lysine levels increased and crude protein utilizability tended to be increased as protein levels increased. 4. Abdominal fat content was lowest in bird fed control diet and was high in birds fed low protein diet Carcass percentage was highest at control and the abdominal fat content was higher in bird fed lower protein diet than bird fed other protein diets(P＜0.05). 5. Feed cost per kg weight gain was lowest at $T_3$ which contained more soybean oil meal than other feeds and next was control. According to the results of this experiment, it was revealed that optimum protein, methionine and lysine levels for starter and finisher broiler diet were 20~18, 0.4~0.32 and 1.1~0.9%, respectively.

• Journal of Korea Soil Environment Society
• /
• v.2 no.2
• /
• pp.9-24
• /
• 1997

Surfactant-aided in situ soil flushing has been proposed as an alternative for the expensive and time consuming 'pump and treat' technology in remediation of contaminated soil and groundwater Injected surfactants can effectively solubilize contaminants sorbed to the soil matrix or nonaqueous phase liquids(NAPLs) in residual saturation. The contaminants solubilized in groundwater are recovered and treated further. The theoretical background of the technology and the results of the field operations, mostly in the US. were summarized. In addition, the factors crucial to the successful application of the technology were discussed. Cost analyses and technical limitations in current applications were also discussed. In conclusion, it is likely that in situ surfactant flushing become a viable option for soil remediation in limited cases. Currently, further advances with respect to operation cost and to treatment efficiency are required for more extensive application of the technology. However, the current trends in soil remediation, specially the growing emphasis on risk based corrective action and natural attenuation, will increase the competitiveness of the technology. For example, removal of easily washable contaminants by short term soil flushing followed by long term monitoring and natural attenuation can greatly reduce the operation cost and time.

• Korean Journal of Soil Science and Fertilizer
• /
• v.41 no.4
• /
• pp.260-266
• /
• 2008

Small lysimeter experiment under rain shelter plastic film house was conducted to investigate the effect of soil characteristics on the leaching and soil solution concentration of nitrate and phosphate. Three soils were obtained from different agricultural sites of Korea: Soil A (mesic family of Typic Dystrudepts), Soil B (mixed, mesic family of Typic Udifluvents), and Soil C (artificially disturbed soils under greenhouse). Organic-C contents were in the order of Soil C ($32.4g\;kg^{-1}$) > Soil B ($15.0g\;kg^{-1}$) > Soil A ($8.1g\;kg^{-1}$). Inorganic-N concentration also differed significantly among soils, decreasing in the order of Soil B > Soil C > Soil A. Degree of P saturation (DPS) of Soil C was 178%, about three and fifteen times of Soil B (38%) and Soil A (6%). Prior to treatment, soils in lysimeters (dia. 300 mm, soil length 450 mm) were tabilized by repeated drying and wetting procedures for two weeks. After urea at $150kg\;N\;ha^{-1}$ and $KH_2PO_4$ at $100kg\;P_2O_5\;ha^{-1}$ were applied on the surface of each soil, total volume of irrigation was 213 mm at seven occasions for 65 days. At 13, 25, 35, 37, and 65 days after treatment, soil solution was sampled using rhizosampler at 10, 20, and 30 cm depth and leachate was sampled by free drain out of lysimeter. The volume of leachate was the highest in Soil C, and followed by the order of Soils A and B, whereas the amount of leached nitrate had a reverse trend, i.e. Soil B > Soil A > Soil C. Soil A and B had a significant increase of the nitrate concentration of soil solution at depth of 10 cm after urea-N treatment, but Soil C did not. High nitrate mobility of Soil B, compared to other soils, is presumably due to relatively high clay content, which could induce high extraction of nitrate of soil matrix by anion exclusion effect and slow rate of water flow. Contrary to Soil B, high organic matter content of Soil C could be responsible for its low mobility of nitrate, inducing preferential flow by water-repellency and rapid immobilization of nitrate by a microbial community. Leached phosphate was detected in Soil C only, and continuously increased with increasing amount of leachate. The phosphate concentration of soil solution in Soil B was much lower than in Soil C, and Soil A was below detection limit ($0.01mg\;L^{-1}$), overall similar to the order of degree of P saturation of soils. Phosphate mobility, therefore, could be largely influenced by degree of P saturation of soils but connect with apparent leaching loss only more than any threshold of P accumulation.

• Journal of Chest Surgery
• /
• v.42 no.5
• /
• pp.576-587
• /
• 2009

Background: The up-regulation of the nitric oxide (NO)-cGMP pathway might be involved in the change of vascular reactivity in rats 3 days after they suffer acute myocardial infarction. However, the underlying mechanism for this has not been clarified. Material and Method: Acute myocardial infarction (AMI) was induced by occluding the left anterior descending coronary artery (LAD) for 30 min (Group AMI), whereas the sham-operated control rats were treated similarly without LAD occlusion (Group SHAM), The concentration-response relationships for phenylephrine (PE), KCl, acetylcholine (Ach) and sodium nitroprusside (SNP) were determined in the endothelium intact E(+) and endothelium denuded E(-) thoracic aortic rings from the rats 3 days after AMI or a SHAM operation. The concentration-response relationships of PE in the E(+) rings from the AMI rats were compared with those relationships in the rings pretreated with nitric oxide synthase (NOS) inhibitor $N{\omega}$-nitro-L-arginine methyl ester (L-NAME) or the cyclooxygenase inhibitor indomethacin. The plasma nitrite/nitrate concentrations were checked via a Griess reaction. The cyclic GMP content in the thoracic aortic rings was measured by radioimmunoassay and the endothelial nitric oxide synthase (eNOS) mRNA expression was assessed by real time PCR. Result: The mean infarct size (%) in the rats with AMI was $21.3{\pm}0.62%$. The heart rate and the systolic and diastolic blood pressure were not significantly changed in the AMI rats. The sensitivity of the contractile response to PE and KCl was significantly decreased in both the E(+) and E(-) aortic rings of the AMI group (p<0.05). L-NAME completely reversed these contractile responses whereas indomethacin did not (p<0.05). Moreover, the sensitivity of the relaxation response to Ach was also significantly decreased in the AMI group (p<0.05). The plasma nitrite and nitrate content (p<0.05), the basal cGMP content (p<0.05) and the eNOS mRNA expression (p=0.056) in the AMI rats were increased as compared with the SHAM group. Conclusion: Our findings indicate that the increased eNOS activity and the up-regulation of the NO-cGMP pathway can be attributed to the decreased contractile or relaxation response in the rat thoracic aorta 3 days after AMI.

• The Korean Journal of Food And Nutrition
• /
• v.27 no.2
• /
• pp.175-182
• /
• 2014

This study investigates the free radical-scavenging activities of Amaranth (Amaranthus spp. L.) red and purple flower extracts. The methanol and hot water extracts of flower are being evaluated for its total polyphenol and flavonoid contents, scavenging activities by the DPPH and ABTS analysis, SOD-like activity, and inhibition activities of superoxide radical on the HL-60 cells and nitric oxide of the RAW 264.7 cells. The PFM (purple flower extracted with MeOH) showed the highest total phenolic and flavonoid content, 606.95 mg GAE/100 g and 254.69 mg CE/100 g, respectively. Amongst the scavenging activities of the DPPH radicals, PFM($RC_{50}=155.06{\mu}g/m{\ell}$) is the highest of all the samples. The ABTS radical-scavenging activity is also highest for PFM (53.16%) at the $250{\mu}g/m{\ell}$ concentration. But, the SOD-like activity of the PFW (purple flower extracted with hot water) increases more than 3 folds of the PFM. In the leukemia HL-60 cell, the PFM shows strongly inhibited superoxide radical generations at a concentration of $200{\mu}g/m{\ell}$ at 72.34%, which increases with 1.79 folds more than the RFW (red flower extracted with hot water). The inhibition activity of nitric oxide in Raw 264.7 cells is the highest for PMF (46.90%) at a $250{\mu}g/m{\ell}$ concentration. In conclusion, PMF show the highest flavonoid contents and the most powerful free radical-scavenging activity. Our results suggest that the increase of antioxidant activities depend on flavonoid contents. Thus, Amaranth flower can be useful for natural antioxidant compounds.