• The Korean Journal of Zoology
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• v.32 no.4
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• pp.404-411
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• 1989

In this study, we attempted to determine the precise patterns of protein synthesis during the second cleavage in mouse. F1 hybrid 2-cell embryos showing a highly synchronized cell cycle and outbreed ICR strain 2-cell embryos were used. The patterns of protein synthesis during the second cleavage showed the sequential changes in the F1 hybrid and ICR strain 2-cell embryos. Moreover, we examined the effects of mitotic and transcriptional inhibitors such as colcemid and a-amanitin on the protein synthesis in the late 2-cell embryos of ICR strain. Treatment of colcemid (0.1mg/ml) blocked the second cleavage, but did not affect on the change of protein synthesis. However, treatment of a-amanitin induced the synthesis of two set of polypeptides without affecting on synthesis of other proteins and cleavage. It thus seems that the appearance of a-amanitin-sensitive proteins may be not involved in the second cleavage. Therefore, these results indicate that the second cell cycle in mouse embryos appears to be regulated at post transcriptional level, presumably independent on the expression of embryonic genome. 본 연구는 생쥐 배아의 2세포기 분열과정중 단백질 합성양상과 단백질합성에 미치는 colcemid와 $\alpha$-amanitin의 영향을 조사하였다 이를 위하여 체내 수정된 ICR strain의 2세포기 배아와 매우 일치된 초기배아 분열양상을 보여주는 체외 수정된 F1 (C57BL x CBA) hybrid 2세포기 배아를 사용하였다. 두 종류의 2세포기 배아에서 단백질 합성은 분열단계에 따라서 매우 일치된 변화를 보여 주었다. 또한 유사분열 억제제인 colcemid (0.1mg/ml)의 처리는 2세포기 배아분열을 억제하였으나, 단백질 합성에는 아무런 변화를 주지 못하였다. 그리고 후기 2세포기 배아에 전사 억제제인 a-amanitin (100mg/ml)을 처리하였을 때 세포분열이나 다른 단백질의 합성에는 아무런 영향이 없이 단지 두개의 단백질의 합성만을 유도하였다. 이는 아마도 a-amanitin의 stress효과에 기인하는 것으로 추측된다. 따라서 생쥐 2세포기 배아의 분열과정은 배아게놈의 유전자 발현과는 무관하게 이미 합성되어 존재하는 mRNA에 의하여 조절되는 것으로 사료된다.

• Clinical and Experimental Reproductive Medicine
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• v.22 no.2
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• pp.191-201
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• 1995

Transcriptional activation of the embryonic genome initiates at 2-cell stage in mouse embryo and is characterized by the synthesis of TRC which is restricted to 2-cell stage. To investigate the roles of various protein kinases on the embryonic gene activation, the effects of protein kinase inhibitors on in vitro development and protein synthetic profiles of the early mouse embryos were examinded. None of ${\alpna}-amanitin$ which is a mRNA synthetic inhibitor, H8 which is a PKA inhibitor, and H7 which is a PKC inhibitor, affected on first cleavage of mouse 1-cell embryos in vitro. However, all of these drugs inhibited the second cleavage. When the drugs were removed following treatment for 6 hours, H8 or H7 treatment showed little inhibition on subsequent development of 1-cell embryos to 2-cell stage or further. In contrast, ${\alpna}-amanitin$ irreversibly inhibited the development of 1-cell embryos to 2-cell stage following removal of the drug. Genistein, a TPK inhibitor, inhibited both the first cleavage of 1-cell embryos and the second cleavage of 2-cell embryos, suggesting that TPK activity may be important during the early cleavages. All of the above four drugs inhibited TRC synthesis as shown by the fluorographic analysis of $[^{35}S]-Met$ labeled protein profiles. When late 1-cell embryos were treated with H7 and analyzed synthetic patterns of $[^{35}S]-Met$ labeled protein, the quantitative differences of protein synthesis on SDS-PAGE appeared on 77 kD and 33 kD region at $32{\sim}38$ hours post hCG. From these studies, transcriptional activation of embryonic genome is not essenting to the mouse 1-cell embryos to develop to 2-cell stage. Hawever, TPK activity is reguisite for both the first cleavage and second cleavage. Similarly, both PKC and PKA activities are required for the second cleavage of mouse embryos, but not for the first cleavage.

• Journal of the Korean Society for Heat Treatment
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• v.26 no.6
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• pp.306-316
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• 2013

Microstructure and fracture behavior of a multi-phase low-density steel were investigated. After hot-rolling and heat treatment, the microstructure of low-density steel was composed of coarse ferrite grains and elongated bands which include second phases such as austenite, martensite and ${\kappa}$-carbide depending on holding time during isothermal heat treatment. After tensile test, microcracks were observed at martensite or ${\kappa}$-carbide interface in the elongated bands. Coarse ferrite grains showed cleavage fracture behavior regardless of second phase. The cleavage fracture of ferrite could be attributed to their coarse grain size and solute atoms that increase ductile-to-brittle transition temperature of ferrite. Despite of the tendency of cleavage fracture in coarse ferrite grains, a specimen having coarse spheroidized ${\kappa}$-carbide particles in the elongated bands showed high total elongation of 30%. Thus, the easiness of plastic deformation in the elongated band seems to play an important role in retardation of cleavage crack formation in coarse ferrite grains.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.674-678
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• 1991

Methanolysis of a ${\beta}$-lactam ring of a cephalosporin was simulated with AM1 semiempirical quantum mechanical calculation. The tetrahedral intermediate TD1 from an O-protonated cephalosporin and a methanol transfers the proton intramolecularly to the C-4 carboxylate to generate an oxyanion, i.e., second tetrahedral intermediate TD2, which undergoes the amide bond cleavage without further protonation on the N-5. For this cleavage a low-energy barrier TS2 was located. According to the energy diagram, tetrahedral intermediates easily undergo ring cleavage even without the protonation on the amide nitrogen.

• Bulletin of the Korean Chemical Society
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• v.17 no.4
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• pp.353-357
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• 1996

Second-order rate constants have been measured spectrophotometrically for the reaction of 2,4-dinitrophenyl X-substituted benzenesulfonates with Z-substituted phenoxides in absolute ethanol at 25.0±0.1 ℃. The nucleophilic substitution reaction gives both S-O bond and C-O bond cleavage products. The extent of S-O bond cleavage increases significantly with increasing electron withdrawing ability of the sulfonyl substitutent X, while that of the C-O bond cleavage is independent on the electronic effect of the substituent. On the contratry, the effect of the substituent Z in the nucleophilic phenoxide is more significant for the C-O bond cleavage than for the S-O bond cleavage. Aminolyses of 2,4-dinitrophenyl benzenesulfonate (1) with various 1°, 2° and 3°amines have revealed that steric effect is little important. The extent of S-O bond cleavage increases with increasing the basicity of the amines, but decreases with increasing the basicity of the nucleophilic aryloxides, indicating that the HSAB principle is not always operative. Besides, reactant and solvent polarizability effect has also been found to be an important factor in some cases but not always to influence the reaction site.

• Applied Microscopy
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• v.34 no.1
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• pp.71-81
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• 2004

When U. unicinctus mature oocytes were fertilized in vitro, germinal vesicle breakdown (GVBD) and meioses occurred and the zygotes entered cleavage stage. A modified pattern of spiral cleavages, suggestively based on behavior of mitotic spindles, have been observed in this work. The first and second cleavages were meridional and the third was equatorial, and then followed by repetitions of meridional-equatorial cleavage. The cleavage of the isolecithal egg were equal and holoblastic and its patterns were spiral. The anti-${\alpha}-,-{\beta}$- tubulin reactions and confocal microscopy revealed mitotic apparates tilted obliquely at each mitosis causing oblique displacements of the blastomeres. Despite isolecithal distribution of yolk, this observations implicated that tilting of mitotic apparates induced spiral cleavage and the displacements of blastomeres. However, these features would not be the typical spiral cleavage, but represented a modified pattern of known Spiralian s in the sense of the equal cleavage. During the first cleavage, heart-shaped eggs have been produced. Electron microscopies exhibited the first cleavage furrow extended with its membranous structure deeply into the cytoplasm. Contractile ring has not been observed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.3
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• pp.223-229
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• 1981

A study has been made of the fracture strength and ductility of the dual phase microstructure, in which the martensitic phase encapsulated islands of ferritic phase in association with the cleavage cracking of ferrite grains. It was found the final fracture occured in a brittle manner, starting from the Griffith crack which consisted of the cleavage crack in the ferrite grains and the cracks in second phase. Furthermore, the effects of the ferrite grain sizes on the Griffith crack were also discussed.

• Clinical and Experimental Reproductive Medicine
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• v.46 no.3
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• pp.119-124
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• 2019

Objective: It is widely accepted that aging decreases women's fertility capacity. The aim of this study was to assess correlations between maternal age and the morphokinetic parameters and cleavage pattern of embryos. Methods: The morphokinetics of embryos derived from women < 30, 30-35, 36-40, and > 40 years of age were compared retrospectively in terms of time of second polar body extrusion, time of pronuclei appearance, time of pronuclei fading, and time of two to eight discrete cells (t2-t8). Furthermore, abnormal cleavage patterns such as uneven blastomeres at the two-cell stage, cell fusion (Fu), and trichotomous mitoses (TM) were assessed. Results: Only t5 occurred later in women aged 36-40 and > 40 years when compared with those aged < 30 and 30-35 years (p< 0.001). Other morphokinetic timing parameters, as well the presence of uneven blastomeres, were comparable between the groups (p> 0.05). However, Fu and TM were more common in women aged > 40 years than in younger women (p< 0.001). Conclusion: Maternal age was correlated with the cleavage pattern of embryos. Therefore, evaluating embryo morphokinetics may contribute to optimal embryo selection, thereby increasing fertility in patients with advanced maternal age.

• Economic and Environmental Geology
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• v.16 no.2
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• pp.111-123
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• 1983

The studied area is situated in tho southern part of the Ogcheon fold belt, where the "Ogcheon Group" is widespread with Jurassic and Cretaceous intrusions. The regional stratigraphy may be divided into three formations, the lower pebble bearing phyllitic, the middle dark grey phyllitic, and the upper black phyllitic formations. For the purposes of the present study, the area has been partitioned to three structural subareas based on major fold axes and fault line. The main subjects of the research have been discussed from two different points, multiple deformation and minor-micro fold styles. The former is analyzed by pebble elongation, folding and lineation in a pebbly formation as well as schistosity, crenulation cleavage and crenulated lineation in the phyllitic formation. The later describes the characteristic features of fold style in each formation and structural subarea. Although minor fold axes within broad pelitic rocks usually tend to trend northeast and to plunge northward, most of these were probably formed by two stages, first a similar fold phase and second a kink fold phase. Measured structural elements indicate that crenulation cleavage in phyllite formed parallel to fold axes of folded pebble followed a NE phase of first deformation and a fold axes of pebbles diagonal to bedding of phyllite are represented by a NW phase of a second deformation. Microscopically, quartz and mica grains form a micro fold enabling one to establish tectonic levels which occur in different deformation modes in each stratigraphic sequence. Microtextures such as crenulation cleavage, kink band, aggregate band of mica and pressure shadows of porphyroblast of quartz related to qarnet and staurolite may suggest the time relation of crystallization and tectonism. The result of this study may conform that three deformation phase, NE first phase-NE second phase-NW phase, occurred in the area.

• Journal of Korea Foundry Society
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• v.21 no.1
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• pp.24-32
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• 2001

Recently, iron aluminides based on Fe3Al and FeAl are ordered intermetallic alloys that offer good oxidation resistance, excellent sulfidation resistance, and potentially lower cost than many high-temperature structural materials. They have better strength, elasticity to weight ratio and high temperature strength, therefore, they can be cosidered as candidate heat resistance structural materials for automobiles, ships, airplanes and spaceships applications. The changes in the mechanical properties and fracture behavior were investigated for Fe-30at.%Al-5at.%Cr alloys when Ti, Hf and Zr were added respectively. For mechanical properties such as Rockwell hardness and yield strength at room temperature, those were decreased in the case of Fe-30at.%Al-5at.%Cr alloy then increased in the case of 5at.% and 10at.% addition of Ti alone. However, Rockwell hardness and yield strength decreased again at 15%Ti then increased dramatically due to the precipitation hardening of the second phase on the specimen at 20%Ti. For fracture modes, cleavage fracture showed in the case of Fe-30at.%Al and Fe-30at.%Al-5at.%Cr alloys. As the amount of Ti addition changed cleavage to transgranular fracture and to quasi-cleavage fracture at 20%Ti. When Hf, Zr and Hf+Zr were added respectively, transgranular, cleavage and quasi-cleavage fracture were coexisted.