• Electrical & Electronic Materials
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• v.9 no.3
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• pp.265-269
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• 1996

We have studied the effect of the mesogenic core of nematic liquid crystals (NLCs) for polar (out-of-plane tilt) anchoring strength and surface order parameter on rubbed polyimide (PI) surfaces. The order of polar anchoring strength for NLCs on rubbed PI surfaces is 5CB > PCH5 > CCH5. From the above results, we suggest that the polar anchoring strength depends on the polarizability of the NLCs. The surface order parameter for NLCs is 5CB > PCH5 > CCH5 on rubbed PI surfaces. We conclude that the polar anchoring strength is strongly related to the surface order parameter on rubbed PI surfaces.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.506-509
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• 2003

In this paper, the $\Phi$-q-n pattern and average discharge power of silicone rubber have investigated effect of inter impurities. It's changed impurities by silicone oil, water and copper. Applied voltage is AC 3, 4, 4.5, 5, 5.5[kV]. And data acquisition time is 10 second(600 cycles). These results suggest that partial discharge(PD) is shower negative polar than positive polar at 3[kV]. Positive polar's PD value increased with increase of applied voltage. The Conductivities expressed same $\Phi$-q-n pattern in positive polar and negative polar at phase region.

• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1309-1338
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• 2002

The fluorescence and photoisomerization quantum yields of trans-1-(9-anthryl)-2-(4-pyridyl)ethene (t-4-APyE), 1-(10-methyl-9-anthryl)-2-(4-pyridyl)ethene (t-4-MeAPyE), and 1-(10-chloro-9-anthryl)-2-(4- pyridyl)ethene (t-4-ClAPyE) were measured in cyclohexane, acetonitrile, and methanol at room temperature.Polar solvents result in the drastic reduction of fluorescence quantum yield and increase of photoisomerization quantum yield for all three compounds. These results are probably due to the stabilization of intramolecular charge transfer (ICT) excited state in polar solvent. The higher contribution of ICT in the presence of more electron-donating methyl substituent, manifested by largest positive fluorescence solvatochromism, indicates that the pyridine ring acts as an electron acceptor. Protonation or methylation makes pyridine ring stronger electron acceptor and causes long-wavelength ground state charge transfer absorption band and complete quenching of fluorescence. The fluorescence from t-4-APyE derivatives can be switched off responding external stimuli viz. medium polarity, protonation, or methylation.

• Electrical & Electronic Materials
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• v.5 no.4
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• pp.439-445
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• 1992

최근 광자기 기록매체로 주목받고 있는 RE-TM계 비정질 박막을 T $b_{x}$ (F $e_{0.9}$ $Co_{0.1}$)$_{100-x}$ (x=14, 17, 20, 23, 27[at%])의 조성비를 갖는 모합금을 만든후 진공증착방법으로 합금박막을 제작하였다. 각시료의 조성에 따른 자기광학효과를 알아보기 위하여 80K부터 600K에서 포화자화( $M_{s}$ )와 보자력( $H_{c}$)에 대한 온도의존성과 자기이방성상수(Ku), Polar Kerr 이력곡선을 측정하였다. 또한 Curie 온도 근처에서 열처리 시간에 따른 자기 토크 곡선의 변화를 분석 함으로써 합금박막 표면의 산화정도를 정성적으로 평가할 수 있었다. 실험결과 T $b_{22.72}$(F $e_{68.78}$ $Co_{8.5}$)인 시료가 상온에서 8.4KOe의 보자력을 가졌으며 T $b_{x}$(x=23[at%])인 경우가 가장 큰 수직자기이방성을 나타냈다. Polar Kerr 이력곡선은 Tb함량 x=25~26[at%]에서 부호가 반전됨을 알 수 있었다.다.다.다.

• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.592-601
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• 2013

This work, which was about the synthesis of 3-(1,8-Naphthalimido) propyl methacrylate and GMA copolymers and their physical properties, investigated the compositions of the copolymer, the reactivity ratios of the monomer, resonance effect(Q), polar effect(e) and fluorescence effect of 1,8-naphthalicanhydride. Azobisisobutyronitronitryl(AIBN) as an initiator was employed at $60^{\circ}C$ with dimethylformamide(DMF) of solvent for the copolymerization of NIPM. $r_1$ was found to be higher than $r_2$ from the reactivity ratios of the monomer obtained from F-R and K-T methods. NIPM was found to be more copolymerized than GMA. The fluorescence spectrums of these polymers showed a weak monomer fluorescence band at 380 nm and a strong excimer fluorescence band at about 460 nm.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.139-150
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• 1998

We measured the terrestrial nightglow of OI $6300{\AA}$ in the thermosphere (~250km) using a ground-based Fabry-Perot interferometer at the King Sejong Station, Antarcticfrom March through September, 1997. The King Sejong Station is located at high latitude geographically ($62.22^{\circ}S,\;301.25^{\circ}E$) but at mid latitude geomagnetically ($50.62^{\circ}S,\;7.51^{\circ}E$). It is therefore the strategic location to measure the temperatures of the thermosphere in the Southern Hemisphere associated with both solar and geomagnetic activities. In this study, we analyzed the observed temperatures inrelation to F10.7 and Kp indices to examine the effect of the solar and the geomagneticactivities on high-latitude neutral thermosphere. During the observing period, the solaractivity was at its minimum. The measured temperatures are usually in the range between about 600~1000 K with some seasonal variation and are higher than those predicted by semi-empirical model, VSH (Vector Spherical Harmonics) and empirical model, MSIS (Mass-Spectrometer-Incoherent-Scatter)-86.

• Journal of Ginseng Research
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• v.13 no.1
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• pp.37-41
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• 1989

Reactive metabolites generated by benzo(a)pyrene(BP) monooxygenase(AHH) interact with nucleophiles in DNA and cause mutation and carcinogenesis. We studied the effect of Panax ginseng C.A. Meyer, which induce epoxide hydratase(EH) activity without concomitant induction of AHH activity, on the binding of BP metabolites to DNA in uitro in Sprague Dawley rats. DNA-BP metabolite adducts can be resolved into at least five distinct peaks by elution of a Sephadex LH-20 column with a water methanol gradieNt. These peaks are arbitrarily designated A(most polar) through I(least polar). Of the 5 peaks tentatively assigned to 7,8 biol-9,10-oxide(A),7,8·oxide(B),4,5-oxide(C), and further metabolites of 9-OH-BP(D & E), peaks A, C, D, and I were reduced to 70, 85, 80, and 30% of controls, respectively, and there was no significant change in peak B. In connection with this DNA binding study, BP metabolizing enzymes including AHH, EH, demethylase(DM) activity and cyt. P-450 contents were also investigated in order to compare the BP treated control with ginseng and BP treated test groups. The results showed that the EH activity was increased by 139% over the BP control, the Cyt. P-450 content was increased by 180% over the control value, and DM and AHH activities were also increased to some degree for the BP test group, but there was no significant effect of the ginseng treatment.

• Reproductive and Developmental Biology
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• v.28 no.3
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• pp.187-190
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• 2004

Protein kinase C exists as a family of serine/threonine kinases which are broadly classified into three groups as cPKC nPKC and aPKC depending on their cofactor requirements. Previous studies have shown that the role of PKC in the process of mouse oocyte maturation. For example, phorbol 12-myristate 13-acetate which is known as an activator of cPKC and nPKC inhibits germinal vesicle break down and 1st polar body extrusion in maturing oocytes. In this study, the effect of thymeleatoxin, a specific activator of cPKC not nPKC, was tested comparing with PMA to address the roles of cPKC and nPKC during mouse oocyte maturation. Cumulus-oocyte complex were cultured in M16 medium for 6 or 12 hr with each of these PKC activators to investigate the effect of germinal vesicle breakdown (GVBD) or the extrusion of 1st polar body. IC/sup 50/ of GVBD were at concentrations of 50nM in PMA and 400nM in thymeleatoxin and of 1st polar body extrusion were 20nM in PMA and 200nM in thy- meleatoxin. The results suggest that activation of nPKC is more closely related to the inhibition of GVBD and 1st polar body extrusion than activation of cPKC. Additionally, we found that the oocytes inhibited 1st polar body extrusion with PMA or thymeleatoxin were arrested in metaphase I of first meiosis.

• Journal of Life Science
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• v.30 no.11
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• pp.931-938
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• 2020

Translationally controlled tumor protein (TCTP) is one of the most abundant proteins in various eukaryotic organisms. TCTPs play important roles in cell physiological processes in cancer, cell proliferation, gene regulation, and heat shock response. TCTP is also considered an important factor in the resistance to oxidative stress induced by dithiothreitol or hydrogen peroxide (H₂O₂). Arctic calanoid copepods have a variety of antioxidant defense systems to regulate the levels of potentially harmful reactive oxygen species generated by ultraviolet radiation in the Arctic marine ecosystem. However, information on the antioxidant activity of TCTP in the Arctic Calanus glacialis is still scarce. To understand the putative antioxidant function of the Arctic copepod C. glacialis TCTP (Cg-TCTP), its gene was cloned and sequenced. The Cg-TCTP comprised 522 bp and encoded a 174-amino acid putative protein with a calculated molecular weight of ~23 kDa. The recombinant Cg-TCTP (Cg-r TCTP) gene was overexpressed in Escherichia coli (BL21), and Cg-rTCTP-transformed cells were grown in the presence or absence of H₂O₂. Cg-rTCTP-transformed E. coli showed increased tolerance to high H₂O₂ concentrations. Therefore, TCTP may be an important antioxidant protein related to tolerance of the Arctic copepod C. glacialis to oxidative stress in the harsh environment of the Arctic Ocean.

• Journal of Embryo Transfer
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• v.25 no.3
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• pp.165-169
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• 2010

This study was carried out to assess the effect of vitamin E against the reactive oxygen species (ROS) on chemical activation of in vitro matured oocytes. Bovine oocytes were aspirated from slaughtered ovaries and transferred to maturation medium with or without vitamin E ($100\;{\mu}M$). After 22 hours of culture, oocytes with polar bodies were selected and submitted to activation treatments with or without vitamin E. After activation, oocytes were cultured in mSOF medium and rate of development was monitored. For ROS ($H_2O_2$) detection, in vitro matured and activated oocytes were selected and stained with DCFDA and observed under fluorescence microscope. The ROS contents were not significant differences in IVM rate, activation process and embryonic development to blastocysts with or without vitamin E. The cell number of blastocyst showed significant difference (p<0.05) in embryos matured and activated with vitamin E. The results of the present study demonstrated that the exposure of vitamin E in IVM and activation process improved the quality of embryos evaluated by the cell number of blastocysts.