• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.2
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• pp.64-72
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• 2004

We measured the vertical profiles of $O_2$, H$_2$S, and pH in sediment pore water beneath marine cage fish farms using a microsensor with a 25 ${\mu}{\textrm}{m}$ sensor tip size. The sediments are characterized by high organic material load. The oxygen consumption, hydrogen sulfide oxidation, and sulfate reduction rates in the microzonations (derived from the vertical distribution of chemical species concentration) were estimated by adapting a simple one-dimensional diffusion-reaction model. The oxygen penetration depth was 0.75 mm. The oxic microzonations were divided into upper and lower layers. Due to hydrogen sulfide oxidation within the oxic zone, the oxygen consumption rate was higher in the lower layer. The total oxygen consumption rate integrated with reaction zone depth was estimated to be 0.092 $\mu$mol $O_2$cm$^{-2}$ hr$^{-1}$ . The total hydrogen sulfide oxidation rate occurring within 0.7 mm thickness was estimated to be 0.030 $\mu$mo1 H$_2$S cm$^{-2}$ hr$^{-1}$ , and its turnover time in the oxic sediment layer was estimated to be about 2 minutes. This suggests that hydrogen sulfide was oxidized by both chemical and microbial processes in this zone. The molar consumption ratio, calculated to be 0.84, indicates that either other electron accepters exit on hydrogen sulfide oxidation, or elemental sulfur precipitation occurs near the $O_2$- H$_2$S interface. Total sulfate reduction flux was estimated to be 0.029 $\mu$mol cm$^{-2}$ hr$^{-1}$ , which accounted for more than 60% of total $O_2$ consumption flux. This result implied that the degradation of organic matter in the anoxic layer was larger than in the oxic layer.

• Horticultural Science & Technology
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• v.35 no.1
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• pp.121-130
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• 2017

This study was carried out to investigate a method for producing cultured virus - free ovules for breeding high - quality Citrus cultivars. Ovules from the immature fruits of three citrus cultivars native to Jeju (Dongjeongkyool, Cheongkyool, and Jikak) and two cultivars of Citrus unshiu Marc. (Miyagawa wase and Haryejosaeng) that were thought to be infected with Citrus tristeza virus (CTV) were cultured on MS2 medium (Murashige - Skoog [MS] basal medium containing $500mg{\cdot}L^{-1}$ malt extract, $50g{\cdot}L^{-1}$ sucrose, $1.0 mg{\cdot}L^{-1}$ kinetin, and $8g{\cdot}L^{-1}$ agar). After four weeks of culture, 10, 21, 13, 5, and 7 somatic embryos and 2, 4, 2, 4, and 5 white callus cells (surrounding green somatic embryos) were obtained from Dongjeongkyool, Cheongkyool, Jikak, Miyagawa wase, and Haryejosaeng, respectively. After six weeks of culture, somatic embryos were obtained from cultured cells grown on MT basal medium supplemented with malt extract ($500mg{\cdot}L^{-1}$), lactose ($70g{\cdot}L^{-1}$), and agar ($16g{\cdot}L^{-1}$). Over 60% of the somatic embryos from citrus cultivars native to Jeju developed into normal plants on MS basal medium supplemented with malt extract ($500mg{\cdot}L^{-1}$), sucrose ($50g{\cdot}L^{-1}$), and agar ($8g{\cdot}L^{-1}$) after 10 weeks of culture. Normal plants were regenerated from two Citrus unshiu Marc. cultivars on MT basal medium supplemented with sorbitol (1.0 M), galactose (1.0 M), $GA_3$ ($1.0mg{\cdot}L^{-1}$), and Gelrite ($3g{\cdot}L^{-1}$). The absence of virus in plants generated from cultured ovules was confirmed by RT - PCR and antigen - antibody reactions. Therefore, virus - free Citrus cells can be obtained for breeding high - quality citrus cultivars using the biotechnological technique evaluated in this study.

• Journal of the Korean Vacuum Society
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• v.20 no.6
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• pp.395-402
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• 2011

The nanomechanical properties of fully lithiated and unlithiated silicon nanowire deposited on silicon substrate have been studied with atomic force microscopy. Silicon nanowires were synthesized using the vapor-liquid-solid process on stainless steel substrates using Au catalyst. Fully lithiated silicon nanowires were obtained by using the electrochemical method, followed by drop-casting on the silicon substrate. The roughness, derived from a line profile of the surface measured in contact mode atomic force microscopy, has a smaller value ($0.65{\pm}0.05$ nm) for lithiated silicon nanowire and a higher value ($1.72{\pm}0.16$ nm) for unlithiated silicon nanowire. Force spectroscopy was utilitzed to study the influence of lithiation on the tip-surface adhesion force. Lithiated silicon nanowire revealed a smaller value (~15 nN) than that of the Si nanowire substrate (~60 nN) by a factor of two, while the adhesion force of the silicon nanowire is similar to that of the silicon substrate. The elastic local spring constants obtained from the force-distance curve, also shows that the unlithiated silicon nanowire has a relatively smaller value (16.98 N/m) than lithiated silicon nanowire (66.30 N/m) due to the elastically soft amorphous structures. The frictional forces of lithiated and unlithiated silicon nanowire were obtained within the range of 0.5-4.0 Hz and 0.01-200 nN for velocity and load dependency, respectively. We explain the trend of adhesion and modulus in light of the materials properties of silicon and lithiated silicon. The results suggest a useful method for chemical identification of the lithiated region during the charging and discharging process.

• Parasites, Hosts and Diseases
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• v.28 no.1
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• pp.45-52
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• 1990

Intestinal histopathological changes due to infection with Echinostcma hortense (Trematoda) were studied in rats after experimental infection with the metacercariae. The metacercariae were obtained from the tadpoles of Rana nigrcmaculata, a second intermediate host infected in the laboratory. Total 18 albino rats(Sprague-Dawley) were given 200 matacercariae each and sacrificed on the day 1, 3, 7, 11, 22 or 44 post-infection(PI) Segments of- the small intestine at 1, 3, 5, 8 and 30 cm posterior to the pylorus(PTP) were rejected and studied histopathologically. 1. The flukes were seen to have intruded into the intervillous space in the upper small intestine at early stages(1∼3 days PI), however, they were located mainly in the intestinal lumen at later stages(7∼44 days PI) . The flukes were sucking and destroying the epithelial layers of villi with their oral and ventral suckers. 2. Histopathological changes of the intestine were recognizable in as early as 1∼3 days after infection, and the changes became severer as the infection progressed. 3. The intestinal mucosa was histopathologically characterized by villous atrophy and crypt hyperplasia throughout the infection period. Major villous changes were blunting, fusion, severe destruction and loss of epithelial layers of villi. Villous/crypt(V/C) height ratio was remarkably reduced from 3 : 1 in controls to 1 : 1 in severely infected animals. In the stroma of villi, inaamma- tory cell infiltrations, vascular congestion, edema, and/or fibrosis were recognized. The goblet cells were increased in number after 11 days PI. It was revealed in the present study that the pathological changes in the intestine of rats infected with E. hortense were chieay confined to the mucosal layer of the upper small intestine, however, the changes were very severe accompanying remarkable destruction of villi and loss of mucosal integrity, and persistent until 44 days PI.

• The Korean Journal of Mycology
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• v.12 no.3
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• pp.105-110
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• 1984

Seven seed samples of corn obtained from Kangweon Provincial Office of Rural Development, Kerea were tested for seed-borne fungi, and found that all the samples tested were infected with Fusarium moniliforme to an extent of $6.0{\sim}79.5%$. Severely infected seed samples showed poor germination on blotter. Seed component plating showed that the fungus present not only in tip caps, pericarps and endosperms, but also in embryos. Heavy infection of the fungus caused severe seed rot and seedling blight in soil, but the damage was not severe and many plants grew without any symptoms when the seeds with light infection were sown in soil. However the fungus was frequently detected from inside of the stems of healthy looking seedlings. The results indicate that the fungus transmit from seed to plant systemically. In inoculation experiments, the fungus produced stem rots on corn plants of 110 days old. The cultivar of Hwangok 3 was revealed more susceptible to the fungus than that of Suweon 19.

• Korean journal of applied entomology
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• v.12 no.1
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• pp.1-21
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• 1973

Some experiments were conducted to investigate the effects of the chemosterilant, hempa, on the biology of the rice weevil, Sitophilus oryzae L., and the transmission of the lethal factors in the progeny. One to three days old adult males were fed on the wheat grains treated with concentrations of 0.0625, 0.125, 0.25, and $0.5\%$ of hempa water solution. The effects of the treatment on the mortality, longevity, and the performance of oviposition were examined for the Pl generation, and the hatchability and mortality in the postembryonic development were also tested in the $F_1,\;F_2,\;BC_1,\;F_3,\;and\;BC_2$ generations to analyze the inheritance of the lethal factors. The results obtained were summarized as follows. (1) The average longevity of the treated males were ranged from 26.6 to 30.4 days, and indicated no statistical differences. (2) The mortality of the treated males were ranged between $3.3\%\;and\;13.3\%$ and showed no statistical significance. (3) The overall mean number of eggs laid by a female mated to a treated male with concentrations of 0.0625, 0.125, 0.26 and $0.5\%$ were 3.78, 4.05, 3.75 and 3.61 for the respective treatments, and they were not differ significantly from those of control which were 3.60 per female per 3 day period. The unmated female laid 1.91 in the same period, and significantly differ from those in other experimental groups. (4) The overall mean hatchability of the eggs laid by the females mated with males that had been treated with various concentrations of hempa were 86.82, 64.77, 53.47, 40.33 and $24.78\%$ for the respective concentrations of 0, 0.0625, 0.125, 0.25 and $0.5\%$. The hatchability decreased with the increasing concentrations. (5) The minimum hatchabilities were obtained from the eggs laid in the period of 10-12 days after treatment, then the hatchability increased showing some recovery. The recovery seemed to be very much delayed for the males which had been treated with the greater concentrations. Such a difference in hatchability might be related with the sensitivity of the developmental stages of the sperms, and broader spectrum in the stages and severer effects seemed to be associated with the increased concentrations. (6) The overall mean of larval mortality in the $F_l$ generation were 6.55, 17.89, 27.40, 35.42 and $52.17\%$ for the respective concentrations of 0,0.0625, 0.125,0.25 and $0.5\%$. And there was a tendency to increase in the mortality with the increase of concentrations. (7) The correlation coefficients between per cent sterile eggs and larval mortality for the experimental plots of 0.125, 0.25 and $0.5\%$ treatments showed r=+0.83 and +0.85, respectively, and it seemed to be close correlation between the lethal effects on the embryonic and post-embryonic developments. (8) Since the $SC_{50}$ of the sterile eggs was $0.133\%$ and $SC_{50}$ of the larval mortality was $0.565\%$, it was considered that tile lethal factors expressed more in the egg stages than the larval stages. (9) The ratio of female to male in the $F_l$ adults showed 100 : 125, 100 : 108 and 100 : 124 for the plots of 0.125, 0.25 and $0.5\%$ treatments, respectively. And it n·as considered that the sex ratio distortions might occur with the higher concentrations. (10) When the F, males originated 1.on the eggs had been laid by p, in the period of 16-18 days after treatment, were crossed to normal females $(BC_1)$ and made sib matings $(F_2)$, the per cent sterile eggs of the $BC_1$ generation were 13.88 and $33.04\%$ , and were 31.01 and $38.73\%$ for the $F_2$generation with the plots of 0.0625 and $0.125\%$ treatment, respectively. And these seemed to be a results of the $F_1$ individuals are carrying some chromosomal aberrations (11) The larval mortality was the highest in the $F_2$ plot and followed the female backcross plot, and the least in the male backcrosses. (12) The proportions of 1st and 2nd instar larvae among the larval development at tile 17th day after oviposition were 10.98, 27.26, 32.98 and $15.73\%$ in the normal female $\times$ normal male, $F_1$ female$\times$normal male, normal $female \;\times F_1$ male and $female \;\times F_1$ male plots, respectively. It was considered that the larval development might be delayed by the treatment in the 2nd generation. (13) Per cent larval mortality and sterile eggs were greater in the $F_2$ sib mating plots $(F_3)$ than both of $F_2$ backcrosses. Therefore, it seemed that some of the recessive lethal mutations might affect in the further generations. (14) The sterility, induced by the treatment of chemosterilant, hempa, was considered as the result of the dominant lethal mutations due to chromosomal aberrations such as translocation and/or deletion. The effects of these lethal factors seemed to be inherited tip to 3rd generation after treatment.

• Restorative Dentistry and Endodontics
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• v.25 no.3
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• pp.390-398
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• 2000

The purpose of this study was to evaluate the apical fitness of non-standardized gutta-percha cones in root canals prepared with rotary Ni-Ti root canal instruments of various tapers and apical tip sizes. Simulated sixty curved root canals of plastic blocks were prepared with crown-down technique using rotary root canal instruments of Maillefer ProFile$^{(R)}$ .04 and .06 taper (Maillefer Instrument SA, Switzerland). Specimens were divided into six groups and prepared as follows: Group 1, prepared up to size 25 of .04 taper ; Group 2, prepared up to size 30 of .04 taper ; Group 3, prepared up to size 35 of .04 taper ; Group 4, prepared up to size 25 of .06 taper ; Group 5, prepared up to size 30 of .06 taper ; Group 6 ; prepared up to size 35 of .06 taper. After cutting off the coronal portion of plastic, blocks perpendicular to the long axis of the canal with the use of a diamond saw, apical 5mm of canal space was analyzed. Prepared apical canal spaces were duplicated using rubber base impression material to evaluate two dimensional total area of apical canal space. Various sized gutta-percha cones were applied in the 5mm-apical canal space, which were size 25, size 30 and size 35 standardized gutta-percha cone, Diadent Dia-Pro ISO-.04$^{TM}$ and .06$^{TM}$(Diadent, Korea), and medium-fine (MF), fine (F), fine-medium (FM) and medium (M) sized non-standardized gutta-percha cones (Diadent, Korea). Coronal excess gutta-percha were cut off with a sharp blade. Photographs of impressed apical canal spaces and gutta-percha cones were taken with a CCD camera under a stereomicroscope and stored in a computer. Areas of the total canal space and gutta-percha cones were calculated using a digitalized image analysing program, CompuScope (Sungjin Multimedia Co., Korea). Ratio of apical fitness was obtained by calculating the area of gutta-percha cone to the total area of the canal space. The data were analysed statistically using One-way Analysis of Variance and Duncan's Multiple Range Test. The results were as follows: 1. In canals prepared up to size 25 ProFile$^{(R)}$ of .04 taper, non-standardized MF and F cones occupied significantly more canal space than Dia-Pro ISO-.04$^{TM}$ or size 25 standardized ones (p<0.05). 2. In canals prepared up to size 30 ProFile$^{(R)}$ of .04 taper, non-standardized F cones occupied significantly more canal space than Dia-Pro ISO-.04$^{TM}$ or size 30 standardized ones (p<0.05), and non-standardized MF cones occupied more canal space than size 30 standardized ones (p<0.05). 3. In canals prepared up to size 35 ProFile$^{(R)}$ of .04 taper, there was no significant difference in canal space occupation among non-standardized MF and F, size 35 standardized, and Dia-Pro ISO-.04$^{TM}$ cones (p>0.05). 4. In canals prepared up to size 25 ProFile$^{(R)}$ of .06 taper, non-standardized MF and F cones occupied significantly more canal space than Dia-Pro ISO-.06$^{TM}$, or size 25 standardized ones (p<0.05), and Dia-Pro ISO-.06$^{TM}$, cones occupied significantly more space than size 25 standardized ones (p<0.05). 5. In canals prepared up to size 30 ProFile$^{(R)}$ of .06 taper, non-standardized FM cones occupied significantly more canal space than Dia-Pro ISO-.06$^{TM}$ or size 30 standardized ones (p<0.05), and non-standardized F cones occupied significantly more canal space than size 30 standardized ones (p<0.05). 6. In canals prepared up to size 35 ProFile$^{(R)}$ of .06 taper, non-standardized M and FM, Dia-Pro ISO-.06$^{TM}$ occupied significantly more canal space than size 35 standardized ones (p<0.05). In summary, in both canals prepared with .04 or .06 taper ProFile$^{(R)}$, non-standardized cones showed better fitness than Dia-Pro ISO$^{TM}$ or standardized ones, which was more characteristic in smaller canals.