• Parasites, Hosts and Diseases
• /
• v.24 no.2
• /
• pp.115-120
• /
• 1986

This study was carried out to reveal the effect of temperature, salinity and aeration on maturation and hatching of Fibricola seoulensis eggs. The eggs were incubated and were observed daily for the appearance of eyespots and hatching. The results were summarized as follows. 1. From $4{\sim}5$ days after incubation in distilled water at $28^{\circ}C$ or at $11{\sim}26^{\circ}C$, the eyespots began to appear and the rates of eggs with eyespots were over 90% in $28^{\circ}C$ on the 7th or 8th day. However, eyespots did not appear in $5{\sim}15^{\circ}C$ or $4^{\circ}C$ by the 18th day. 2. The mature eggs began to hatch at the 8th day, and hatching rate 2 weeks after incubation was over 90% at $28^{\circ}C$, but it was below 5% at $11{\sim}26^{\circ}C$, and 0% at $5{\sim}15^{\circ}C$ and at $4^{\circ}C$. 3. Aeration did not influence the appearance of eyes pots nor hatching. 4. In salines under 0.6%, the rates of eyespots appearance were over 90% on the 7th day. The rate was 55.0% in 0.9% at 20 days, and 0% in 1.2%. 5. The hatching rates in salines below 0.3% concentration were over 90% by 14 days of incubation. However, the rate decreased to 44% in 0.6% saline and to 0% over 0.9% salinity. 6. The eggs incubated in the dark hatched in 12.5% on the 10th day, but hatching rate of mature eggs increased to 85.7% within 2 hours after exposure to light. Above results demonstrated that the best temperature for maturation and hatching of F. seoulensis eggs was $28^{\circ}C$, and the miracidia began to hatch at $8{\sim}9$ days after incubation. In the field, hatching and invasion into snails of the miracidia may occur from May to September in Korea. In salines under 0.3% concentration maturation and hatching were not influenced, but as salinity increased hatching was inhibited more than maturation was.

• Pediatric Infection and Vaccine
• /
• v.10 no.2
• /
• pp.215-222
• /
• 2003

Purpose : This study was to analyze serious bacterial infections in infants younger than three months of age and to review the direction of treatments for these patients. Methods : 378 febrile infants with a rectal temperature ${\geq}38.0^{\circ}C$ visited from Jan. 2001 through Dec. 2002 were retrospectively studied. Infants with the following criteria belonged to the low risk group. WBC $5,000{\sim}15,000/mm^3$, WBC negative in urine stick test and negative for nitirite test, CSF WBC < $10/mm^3$ and negative in CSF gram stain, negative chest X-ray, stool WBC <5/HFP(high power field), and focal infection. If any of the above criteria were not met, they belonged to the high risk group. SBI was defined as a positive culture of urine, blood or CSF. SI was defined as aseptic meningitis or pneumonia including above laboratory tests of SBI. SBI patients were separately compared with two groups, high risk and low risk. Results : Of the 378 infants that were tested 216(57.1%) were in the high risk group and 162(42.9%) in the low risk group. Among 105 SBI(27.8%) and 172 SI(45.5%), there were 98 urinary tract infection(25.2%), 10 bacteremia(2.6%), 2 bacterial meningitis(0.6%), and 77 aseptic meningitis(22.8%). There were 76 SBI(35.2%) from the high risk group and 29 SBI(17.9%) from the low risk group identified. The results of the sensitivity(72.4%), the specificity(48.7%), the negative predictive value(82.1%) and the positive predictive value (35.2%) were calculated. Conclusion : Even though the probability of SBI in the low risk group is insignificant, it should still be considered in febrile infants younger than 3 months of age. I believe the CSF study is necessary because of the moderate high incidence of abnormal finding in our study.

• Radiation Oncology Journal
• /
• v.15 no.3
• /
• pp.197-206
• /
• 1997

Purpose : Phospholipase D (PLD) catalyzes the hydrolysis of phosphatidylcholine to phosphatidic acid (PA) and choline. Recently, PLD has been drawing much attentions and considered to be associated with cancer Process since it is involved in cellular signal transduction. In this experiment, oleate-PLD activities were measured in various tissues of the living rats after whole body irradiation. Materials and Methods : The reaction mixture for the PLD assay contained $0.1\;\muCi\;1,2-di[1-^{14}C]palmitoyl$ phosphatidylcholine 0.5mM phosphatidylcholine, 5mM sodium oleate, $0.2\%$ taurodeoxycholate, 50mM HEPES buffer(pH 6.5), 10mM $CaCl_2$, and 25mM KF. phosphatidic acid, the reaction product, was separated by TLC and its radioactivity was measured with a scintillation counter. The whole body irradiation was given to the female Wistar rats via Cobalt 60 Teletherapy with field size of 10cmx loom and an exposure of 2.7Gy per minute to the total doses of 10Gy and 25Gy. Results : Among the tissues examined, PLD activity in lung was the highest one and was followed by kidney, skeletal muscle, brain, spleen, bone marrow, thymus, and liver. Upon irradiation, alteration of PLD activity was observed in thymus, spleen, lung, and bone marrow. Especially PLD activities of the spleen and thymus revealed the highest sensitivity toward $\gamma-rar$ with more than two times amplification in their activities In contrast, the PLD activity of bone marrow appears to be reduced to nearly $30\%$. Irradiation effect was hardly detected in liver which showed the lowest PLD activity. Conclusion : The PLD activities affected most sensitively by the whole-body irradiation seem to be associated with organs involved in immunity and hematopoiesis. This observation s1ron91y indicates that the PLD is closely related to the physiological function of these organs, Furthermore, radiation stress could offer an important means to explore the phenomena covering from cell Proliferation to cell death on these organs.

• 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.

• Journal of Soil and Groundwater Environment
• /
• v.14 no.6
• /
• pp.78-86
• /
• 2009

Applicability of CaO and steel slag as stabilizers in the treatment of field and paddy soils near Pungjeong mine contaminated with arsenic and cationic heavy metals was investigated from batch and column experiments. Immobilization of heavy metals was evaluated by TCLP dissolution test. Immobility of heavy metal ions was less than 15% when steel slag alone was used. This result suggests that $Fe_2O_3$ and $SiO_2$, known as the major component of steel slag, have little effect for the immobilization of heavy metal ions due to acidity of TCLP solution. Immobilization of cationic heavy metals was little affected by the ratio of CaO and steel slag while arsenic removal was increased as the ratio of steel slag to CaO increased. In the column test, concentrations of both arsenic and cationic heavy metals in effluents were below the water discharge guideline over the entire reaction period. This result can be explained by the immobilization of cationic heavy metals from the increased pH in soil solution as well as by the formation of insoluble $Ca_3(AsO_4)_2$. From this work, it is possible to suggest that arsenic and cationic heavy metals can be concurrently stabilized by application of both CaO and steel slag.

• Korean Journal of Soil Science and Fertilizer
• /
• v.14 no.1
• /
• pp.24-30
• /
• 1981

A pot Experiment and a field investigation were carried out in order to obtain some information on the ammonia volatilization and nitrogen absorption by paday rice plants in relation to the potassium application and roots growth. Results obtained were as follows ; 1. Urea application to the polt where potassium was added and rice plant was grown increased the ammonia volatilization at the beginning, but in the latter stage, the volatilization gradually decreased below that of no potassium plot. 2. Total nitrogen absorbed by rice plant, however, was much greater from the potassium added plot than no potassium and pH of the wet soil was lower in the former treatment than in the latter. 3. The application of urea presumably caused greater raise of soil pH and higher ammonia valatilization from the potassium added plot than the no potassium at the beginning, but the active growth of plants and raveneous absorption of N by the plants at the later stage of plant growth resulted in lower ammonia volatilization and lower pH in the potassium added plot than no potassium plot. 4. When the penetration of rice roots was restricted, pH of the wet soil was lower in the plot where potassium added than no potassium, and so was the ammonia volatilization. 5. Under high pH condition of paddy soil, a heavier basal application of potassium chloride or potassium sulfate may reduce the ammonia volatilization particulary in the early growth period of paddy rice when the nutrient absorption by plant is insignificant. However, under an acid normal soil, it may cause ammonia loss through raise of soil pH at the early growth of paddy rice.

• Korean Journal of Soil Science and Fertilizer
• /
• v.12 no.1
• /
• pp.15-23
• /
• 1979

In the first paper of the series the five soil fertility factors were evaluated by means of principal component analysis and varimax method. They are interpreted as representing, 1) skeletal available phosporus status, 2) organnic matter status, 3) salt status 4) base status, and 5) free oxide status. In order to resynthesize such fragmented information for the overall soil fertility evaluation, the method of multiple regression analysis was adopted, using the five factor scores and yield data for Korean paddy soils as independent and dependent variables respectively. As test of linear models with different combinations of independent variables the results of t-test of regression coefficient were revealed that the organic matter status (FII) has no relevance to the yield of paddy and that the free oxides and salt supply has by it self only an insignificant contribution to the yield. The multiple correlation coefficient (R) revealed its multiple regression analysis was as low as 0.43. Introduction of quadratic terms to the linear model bettered the result. Thus multiple correlation coefficient (R) was increased as 0.59. Therefore, a coefficient of determination 0.35 was obtained by a quadratic model with interaction terms among the five fertility constituents. Generally we think that the fertility factor has more contribution to raise the rice yield in paddy and that the failure of yield prediction by fertility factor scores was caused by one of follows; 1) the roughness of the yield inspection, and 2) missextraction of fertility constituents. The second step in this study, assuming that the residuals by multiple regression analysis were due to factors other than soil fertility, we can now proceed to predicting the yield from the field characters with the classified fertility groups by means of Hayashi's theory of quantification No. 1. Such variables as fertility groups (FTYG), water availability (WATER), soil drainage (DRNG), climatic zone (CLIZ), surface soil's stickiness (STCKT), surface soil's dry consistence (DCNST), and surface soil's texture (FTEXT) are taken up as the explanatory variables. The quantification appears reasonable; the well to extremely well in soil drainage, very sticky of surface soil, inefficiency in water availability, coarse texture, and very hard to extremely hard dry consistence in soil are detrimental to the rice yield. The R was as high as 0.90 for the set of variables. But the given explanatory variables in this study were not quite effective in explaining rice yield. The method developed seems to be promising only if properly collected data are available. Conditions that should be satisfied in the yield inspection obtained from common cultivator for the purpose of deriving a prediction equation were put forward.

• Korean Journal of Soil Science and Fertilizer
• /
• v.16 no.1
• /
• pp.28-35
• /
• 1983

The object of this study was to investigate the distribution of Cd fractions in paddy soils in relation to some soil characteristics and to find out the relationships between soil Cd fractions and Cd content in brown rice. Thirty six soils and rice samples were collected from the paddy field adjacent to zinc mining sites at harvest time in 1981. Total Cd content of brown rice samples was analyzed. A sequential extraction procedure was used to fractionate Cd in soils into the designated forms of exchangeable, adsorbed, organically bonded, carbonate, sulfide, and residual Cd. The results obtained were as follows: 1. The distribution of Cd fractions in soil showed a wide difference depending on soil properties. As an average value it was observed that organically bonded Cd amounted 43.7%; residual Cd, 6.5%; and other fractions, 10-15%. 2. With higher soil pH, organically bonded and carbonate Cd fraction tended to be higher but exchangeable fraction lower. Other forms of Cd showed no difference with soil reaction. 3. Organically bonded fraction was positively correlated with soil organic matter content, while others except adsorbed fraction showed an adverse tendency. 4. The relation of fraction distribution to soil C E C was similar to the case of organic matter. 5. Cadmium content in brown rice showed significant possitive correlation with organically bonded Cd content (r = 0.655) and carbonate, Cd content of soil (r = 0.328) but there was no significant correlation with contents of other forms.

• Korean Journal of Soil Science and Fertilizer
• /
• v.12 no.1
• /
• pp.1-14
• /
• 1979

The fertility which is the combined factor is one of the important capability determiants of paddy soils. In this study, we aimed at attaining a quantitative evaluation of soil fertility and further establishing an objective fertility classification on the basis of the fertility evaluation. The samples used in this series studies were collected from Korean paddy field. They include deltas, flood plains, coastal plains, valley plains, fans and low terraces. On the basis of correlation analysis, factor analysis was applied to a set of 15 variables. As a result of factor analysis, five mutually independent and clearly definable fertility component factors were extracted from the 15 variables for the whole 90 surface soil samples. The fertility status of each sample soil could be objectively designated by the score of the five factors. As a means of summarizing the information obtained, taxonomic distances between all pairs of the samples were computed from these five factor scores further to be subjected to numerical taxonomy. Seven fertility groups were formulated, each of which was characterized by one or more of the fertility components. As this fertility classification was based on the present state of soil properties, it would be useful in pointing to the proper direction of further fertility amelioration and improvement for each group to enhance potential productivity of Korean paddy fields.

• Korean Journal of Soil Science and Fertilizer
• /
• v.25 no.3
• /
• pp.249-254
• /
• 1992

This research was conducted to investigate the effects of fly ash applications on growth and yield parameters of corn (Zea mays L.), and soil chemical properties. Corn height at silking stage, and height and dry matter ratio at harvesting stage were enhanced by applications of fly ashes derived from bituminous coal and anthracite, respectively. Effects of fly ash treatment on growth parameters of corn were varied with kinds and levels of fly ash application and growth periods, but relatively small without revealing a major negative effect as compared to the control. Yield of corn was increased by applying fly ash of anthracite origin, but other yield components were not influenced negatively by fly ash treatment. Soil total carbon contents, cation exchange capacity, and phosphorus contents of soils sampled after harvest of corn were significantly increased by fly ash treatment, although there were slightly different effects according to kinds and levels of fly ash application. Exchangeable cations of soils were varied within an experimental error range. Phosphorus taken up by corn was enhanced by treating fly ash of the bituminous coal to the soil and there were a positive correlation between phosphorus uptake and soil Phosphorus level. Cation uptake by corn was changed a little, but no significant reduction was observed in cation uptake due to fly ash treatment. It seems to be difficult to figure out the mechanism of fly ash effects on growth and nutrient uptake by corn with one year field experiment, however treatment of fly ash enhanced some parameters of growth and yield, and nutrient uptake by corn without revealing any major negative effects. To determine the value of fly ash as a fertilizer source, continuous researches under various soil and crop conditions were considered to be necessary.