• Restorative Dentistry and Endodontics
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• v.34 no.4
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• pp.333-339
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• 2009

This study was done to determine if there is any difference in microleakage between experimental composite resins, in which various proportions of three component photoinitiators (Camphoroquinone, OPPI, Amine) were included. Four kinds of experimental composite resin were made by mixing 3.2% silanated barium glass (78 wt.%, average size; 1 ${\mu}m$) with each monomer system including variously proportioned photoinitiator systems used for photoinitiating BisGMA/BisEMA/TEGDMA monomer blend (37.5:37.5:25 wt.%). The weight percentage of each component were as follows (in sequence Camphoroquinone, OPPI, Amine): Group A - 0.5%, 0%, 1% / Group B - 2%, 0.2%, 2% / Group C - 0.2%, 1%, 0.2% / Group D - 1%, 1%, 2%. Each composite resin was used as a filling material for round class V cavities (diameter: 2/3 of mesiodistal width; depth: 1.5 mm) made on extracted human premolars and they were polymerized using curing light unit (XL 2500, 3M ESPE) for 40 s with an intensity of 600 mW/$cm^2$. Teeth were thermocycled fivehundred times between $50^{\circ}C$and $550^{\circ}C$for 30s at each temperature. Electrical conductivity (${\mu}A$) was recorded two times (just after thermocycling and after three-month storage in saline solution) by electrochemical method. Microleakage scores of each group according to evaluation time were as follows [Group: at first record / at second record; unit (${\mu}A$)]: A: 3.80 (0.69) / 13.22 (4.48), B: 3.42 (1.33) / 18.84 (5.53), C: 4.18 (2.55) / 28.08 (7.75), D: 4.12 (1.86) / 7.41 (3.41). Just after thermocycling, there was no difference in microleakage between groups, however, group C showed the largest score after three-month storage. Although there seems to be no difference in microleakage between groups just after thermocycling, composite resin with highly concentrated initiation system or classical design (Camphoroquinone and Amine system) would be more desirable for minimizing microleakage after three-month storage.

• Development and Reproduction
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• v.12 no.2
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• pp.195-202
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• 2008

The gonadosomatic index, germ cell differentiation, and the ovarian cycle in female jicon scallop, Chlamys farreri were studied by histologic and cytologic observations. In the early vitellogenic oocyte, the Golgi complex, mitochondria and rough endoplasmic reticulum were involved in the formation of lipid droplets. In the late vitellogenic oocyte, exogenous substances, namely, glycogen particles and lipid granular substances appeared in the germinal epithelium passed into the ooplasm through the microvilli of the envelope. Yolk granules and multivesicular bodies were involved in the formation of proteinecious yolk granules in the late vitellogenic oocyte. Vitellogenesis occurrs by endogenous autosynthesis and exogenous heterosynthesis. The auxiliary cells function as nutritive cells in the formation and development of the previtellogenic and early vitellogenic oocytes in their earlr stages. Monthly changes in the gonadosomatic index were closely associated with ovarian developmental phases. The reproductive cycle of this species can be classified into five stages: early active stage (January to March), late active stage (March to April), ripe stage (April to August), partially spawned stage (June to August), and spent/inactive stage (August to December). Spawning occurred from June to August, and the major spawning season was from July to August when the sea water was at high temperature.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.113-119
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• 2009

Artificial induction of maturation by heating of the hard clam, Meretrix petechiails (Lamarck) broodstock was investigated from 25 May to 30 June in 2008. We experimented maturation by keeping the breeding water temperature at 20, 25 and $30^{\circ}C$ and as the natural water temperature and found the following results. In case of the female, maturation was the quickest in the experiment group of $30^{\circ}C$ and the maturation tended to be slower as the water temperature was lower. The similar trend was displayed among the male. At experiment completion, maturation induction rate was found to be the highest at 46.0% in the experiment group of $30^{\circ}C$ followed by 35.0% in the experiment group of $15^{\circ}C$, 18.0% in the experiment group of natural water temperature and 12.0% in the experiment group of $20^{\circ}C$. During the period of the experiment, the survival rate was of 90% or more in all groups.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.503-514
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• 1997

The morphogenesis of panicle and spikelet in paddy rice has been studied in high yielding Indica$\times$Japonica hybrid cultivar, Milyang 23 and a Japonica type cultivar, Koshihikari. Germinated seeds planted in $5000^{-1}$ a pots filled with submerged soil and cultured under natural conditions. The young panicle of main stem were continuously dissected and observered by Cryo-SEM from the panicle initiation stage until heading stage. Although the date of panicle differentiation and heading in Koshihikari earlier than those of Milyang 23. the sequence of panicle development in two cultivars begins when first bract primordium at opposite side of flag-leaf primordium differentiated, synchronously followed by growth of the primary branch primordia (PBPs) and secondary branch primordia (SBPs), spikelet primordia(SPs), glumes as lateral organs on rachilla and organs composing single floret, and successive sporogenesis in the young spikelets continue after the enclosure by lemma and palea. The PBPs are acropetally initiated from the base of the panicle primordium, and the SBPs alternately differentiate from the base of upper PBP which differentiate later than the lower PBP. Spikelet development starts at the top of upper side PBP of the young panicle and continue basipetally even though SBPs continue to develop at the lower primary branch. Each PBP, SBP and SP differentiate with differentiation bract or bract hair cell around the base of each their primordia. The observation could confirm that Milyang 23 has not only 2~3 more defferentiated PBPs, but also more SBPs and SPs especially from middle-lower primary branch, at end of their differentiation stages, as compared to those of Koshihikari.

• Korean Journal of Plant Resources
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• v.28 no.2
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• pp.259-262
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• 2015

We performed the following experiment to increase the development of shoots in the in vitro culture of hybrid progeny. MS medium was used as the base medium; cytokinins BA at a concentration of 2.0, 3.0, or 5.0 ㎎/L and TDZ at a concentration of 0.2, 0.3, or 0.5 ㎎/L were added to the in vitro cultures. For the FO progeny, the shoot development rate was highest of 18% with 2.0 ㎎/L BA, at 18%, and 3.0 ㎎/L and 5.0 ㎎/L BA resulted in a lower rate of 12%. TDZ addition tended to identical or similar results to that of the control media. For the FA progeny, addition of TDZ tended to lead to a higher shoot development rate and was superior with 0.3 ㎎/L treatment. However, the addition of BA to the media resulted in a shoot development rate between 14.3% and 15.7%, similar to that of the control.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.105-112
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• 2009

We investigated the degree of obesity, histological development stages of gonads and sexual maturation induction rates of comb pen shell, Atrina pectinata, per the type of micro-algae supplied. Terms of maturation by singular or mixed supply of microalgae, it was found that maturation of the female was the quickest at 60.0% by the Tetraselmis tetrathele (Tet). experiment group followed by 57.1% by the Chlorella ellipsoidea (Chl). experiment group and 16.7% by the Phaeodactylum tricornutum (Pha). experiment group. However, there were no significant differences between Tet. experiment group and Chl. experiment group. As for the male, maturation was the quickest at 60.0% by the Tet. experiment group followed by 16.7% by the Chl. experiment group and 14.3% by the Pha. experiment group. In light of these results, Tet. is concluded to be a very useful feed organism in breeding the mother comb pen shells. Upon completion of the experiment, the sexual maturation induction rate for the female was found to be the highest at 82.0% in the Tet. experiment group followed by 72.0% by the Chl. experiment group, 64.0% by the Pha. experiment group and 58.0% by the mixed micro-algae experiment group. During the period of experiment, the survival rate was the highest at 94.4% by the mixed micro-algae experiment group followed by 90.0% by the Pha. experiment group, 83.1% by the Tet. experiment group and 78.8% by the Chl. experiment group.

• Journal of the Korean Electrochemical Society
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• v.13 no.2
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• pp.116-122
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• 2010

A $Cu_3Si$ film electrode is obtained by Si deposition on a Cu foil using DC magnetron sputtering, which is followed by annealing at $800^{\circ}C$ for 10 h. The Si component in $Cu_3Si$ is inactive for lithiation at ambient temperature. The linear sweep thermammetry (LSTA) and galvano-static charge/discharge cycling, however, consistently illustrate that $Cu_3Si$ becomes active for the conversion-type lithiation reaction at elevated temperatures (> $85^{\circ}C$). The $Cu_3Si$ electrode that is short-circuited with Li metal for one week is converted to a mixture of $Li_{21}Si_5$ and metallic Cu, implying that the Li-Si alloy phase generated at 0.0 V (vs. Li/$Li^+$) at the quasi-equilibrium condition is the most Li-rich $Li_{21}Si_5$. However, the lithiation is not extended to this phase in the constant-current charging (transient or dynamic condition). Upon de-lithiation, the metallic Cu and Si react to be restored back to $Cu_3Si$. The $Cu_3Si$ electrode shows a better cycle performance than an amorphous Si electrode at $120^{\circ}C$, which can be ascribed to the favorable roles provided by the Cu component in $Cu_3Si$. The inactive element (Cu) plays as a buffer against the volume change of Si component, which can minimize the electrode failure by suppressing the detachment of Si from the Cu substrate.

• Journal of Korean Society of Forest Science
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• v.98 no.1
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• pp.115-124
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• 2009

New strain needs to maintain desirable characteristics for long term when it was bred, but in lapse of time it degenerates into a bad condition. Therefore the influence of temperature on the viability and survival rates of Lentinula edodes strains were examined after cryopreservation. Also, liquid nitrogen preservation for L. edodes has been proved to be one of the most reliable method. However, a mechanical damage of strain is inevitable during cryopreservation of the fungus because the fungus is very sensitive to stress of cooling rate in the freezing process. So we tried to find out state change of L. edodes with a programmable freezer. L. edodes strains were preserved at $-20^{\circ}C$, $-80^{\circ}C$ and $-196^{\circ}C$ for 50 days. At $-20^{\circ}C$, its mycelial growth became extinct. When thawed, the growth of mycelia which were preserved at $-80^{\circ}C$ was fastest. Attempts were made to investigate viability of L. edodes strains after freezing at $-80^{\circ}C$ and $-196^{\circ}C$, respectively. As the result, more than 90% showed high survival rate of strains tested at $-80^{\circ}C$ and $-196^{\circ}C$. Mycelial growth between apical and basal parts of colony after freezing preservation for 50 days was compared. At apical and basal parts, the survival rates showed 100% at $-80^{\circ}C$, but 98% and 94% at $-196^{\circ}C$, respectively. We confirmed that the ice crystal formation temperatures of L. edodes strains were $-6.0^{\circ}C$ for Sanlim 1, $-5.5^{\circ}C$ for the Sanlim 2, $-4.0^{\circ}C$ for the Sanlim 3 and $-15.5^{\circ}C$ for the Sanzo 302. These results indicated that L. edodes strains showed completely different responses to the ice crystal formation. We knew the fact that even the same species, especially L. edodes, they displayed completely different responses to the same freezing condition. Also, this has nothing to do with the connection between temperature type and freezing point. And a protocol was tried to minimize state change of L. edodes strains using programmable freezer when they are frozen, but it was not effective on them.