• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.217-224
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• 2011

Removal of dissolved selenium by D. michiganensis, a iron-reducing bacterium, and effects of dissolved metal elements such as iron, sulfate, and copper were investigated. Selenide that was reduced from selenite (2 mM) by D. michiganensis was gradually removed from the aqueous medium. As the reduced selenide was combined with aqueous iron, it was precipitated as a nanoparticulate iron-selenide. Sulfate and copper negatively affected the microbial selenite reduction, and the copper was especially toxic to the bacterium, inhibiting a microbial removal of dissolved selenite. These results show that it should be carefully biotreated for a selenium-contaminated site considering in situ sulfate or copper distribution and concentration. Consequently, the formation of iron-selenide by bacteria will be an important measure for preventing a long-distance migration of selenium in the subsurface environments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.1
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• pp.105-113
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• 1995

Seasonality in biomass and egg Production was investigated for Calanus sinicus, one of the major copepods in Asan Bay, Korea. Biomass of this species in this restricted embayment showed only one Peak in spring, but e99 Production showed two Peaks, spring (April and May) and fall (September). Average egg Productions during the spawnlng seasons were 16.3 egg/female/day (spring) and 7.6eggs/female/day (fall) with maximum egg Production of 39.0 eggs/female/day. Food concentrations in this bay measured'1 terms of particulate organic carbon (POC) were relatively high around the year, and correlation between egg Production and POC was not significant. With the food Provided sufficiently animals Produced a lot of fecal Pellets, but egg Production was ceased after several days of experiment. From these results it was believed that egg Production in this bay was influenced by food quality and feeding history rather than food concentrations. Habitat temperatures also seem to have influence on egg Production from the tacts that no egg was Produced at extreme habitat temperatures, although the correlation between the two was not significant. In this bay, two generations with different time periods seem to progress yearly. Distribution was coupled with life cycle only at certain time of the year. During the other periods predation pressure by the higher trophic levels and shift of the centers of the distributions toward deeper outer bay seemed to be responsible for the observed distribution and egg Production of this species in this bay. Comparing with the Previous reports, migration of fairly long distance and continual reproduction seemed possible for this species.

• Journal of Periodontal and Implant Science
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• v.32 no.2
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• pp.429-455
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• 2002

There are numerous kind of materials and techniques to regenerate the periodontal tissue which has been lost due to destructive periodontal disease, including bone graft material. Many bone graft materials have been reported and among these materials, synthetic material has been developed fin the long time because of its sufficient supply economically. Calcium sulfate which was evaluated as including much calcium, has been used in the clinical field. In the dental field calcium sulfate has been used as bone graft material and Kim reported that improved bone formation and more amount of new attachment after grafting calcium sulfate. but, because calcium sulfate has the problem that it generates the heat in setting period and resolves fast, we need to evaluate the effect of the improved calcium sulfate on periodontal tissue. The present study evaluates the effect of paste type calcium sulfate on the epithelial migration, alveolar bone regeneration, cementum formation and gingival connective tissue attachment in intrabony defect in dogs. Four millimeter deep and four millimeter wide 3-wall defects were surgically created in the mesial or distal aspects of premolars or molars. the test group received paste-type calcium sulfate with a flap procedure and the control group underwent flap procedure only. Histologic analysis after 8 weeks of healing revealed the following results : 1. The length of epithelial growth(the distance from CEJ to the apical end of JE) was 0.52${\pm}$0.26mm in the control and 0.56${\pm}$0.25mm in the test group. there was no statistically significant difference between the two groups. 2. The length of connective tissue adhesion was 1.74${\pm}$1.06mm in the control and 1.28${\pm}$0.57mm in the test group. there was no statistically significant difference between the two groups. 3. The length of new bone was 2.01${\pm}$0.95mm in the control and 2.62${\pm}$0.81mm in the test group. there was no statistically significant difference between the two groups. 4. The length of new cementum was 1.86${\pm}$0.80mm in the control and 2.77${\pm}$ 0.86mm in the test group. there was a statistically significant difference between the two groups.(P<0.01) These results suggest that the use of paste type calcium sulfate in 3-wall intrabony defects has significant effect on new cementum formation , but doesn't have any significant effect on the prevention of junctional epithelium migration and new bone formation. Finally, the paste type calcium sulfate that is used in this study is suggested to be the material that can have a significant effect on the periodontal healing, if its biocompatibility is improved.

• Korean Journal of Ecology and Environment
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• v.57 no.2
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• pp.102-110
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• 2024

This study presents a fine scale distribution of the endangered species, Odontobutis obscura, through field surveys and literature reviews. Using the mark-recapture method, the population size in major habitats was determined. Field surveys conducted on 18 streams in Geoje Island revealed that the O. obscura was only found in the main streams and tributaries of the Sanyang, Gucheon, and Buchun Streams, which are part of the Sanyang Stream watershed. The O. obscura exhibited relative abundances ranging from 0.5% to 35.3% at different locations, with certain spots showing higher relative abundances (18.8% to 35.3%), indicating major habitat areas. A review of six literature studies confirmed the presence of the O. obscura, although there were differences in occurrence status depending on the purpose, scope, and duration of the studies. Combining the results of field and literature surveys, it was found that the O. obscura inhabits the main and tributary streams of the Sanyang, Gucheon, and Buchun Streams, from the upper to lower reaches. Currently, the O. obscura population in the Sanyang Stream watershed maintains a stable habitat, but its limited distribution range suggests potential issues such as genetic diversity deficiency in the long term. The population size of the O. obscura was confirmed at two specific locations, with densities of 0.5 to 1.5 individuals per m². The average movement distance from the release point was 13.1 m, indicating the limited mobility characteristic of ambush predators. Understanding the distribution and population size of endangered species is the first step towards their conservation and protection. Based on this information, further research could significantly contribute to the conservation of the O. obscura.