• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2002년도 추계학술대회
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• pp.253-259
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• 2002

The value of charge currnet, discharge current, ${\varepsilon}r^'$,${\varepsilon}r^{'}$ residual voltage was measured inorder to investigate electric properties in Ethylene Prophylene Rubber for is irradiated C0$^{60}$$\gamma$ ray 0~38.1 Mrad. The value of charge current and the discharging current of the EPR is influenced by C0$^{60}$-$\gamma$- irradiation dose. The charging current and the discharging current of EPR increas, depending on the ratio of degradation. As the irradiatin dose is increased, the peak of residual voltage moves to the slorter time. The properties specific electric constant due to time variation was appeared dispersion by plentiful C0$^{60}$$\gamma$- irradiation dose. The increase of peak in ${\varepsilon}r^{'}$ is attrib uted to the irratiation dose almost proportionally.

• Corrosion Science and Technology
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• 제2권2호
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• pp.59-67
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• 2003

Electrochemical potentiokinetic reactivation (EPR) tests are used to evaluate the degree of sensitization (DOS) of stainless steels and nickel base alloys. The validity of EPR test to detect DOS of these alloys, however, depends all the electrolyte composition employed. The existence of precipitates such as NbC, and TiC, etc. in the alloys also affects the reactivation behaviors of these alloys. In this investigation, the reactions involved during EPR processes are analyzed. In 0.5 M $H_2SO_4$+ 0.01 M KSCN electrolyte, a reactivation peak associated with the localized attack around NbC, different from that of intergranular corrosion, is observed for the solution annealed 347 SS. For solution annealed Alloy 600, matrix corrosion and localized attack around TiC with distinct anodic peaks appeared in the EPR curves are seen in the $H_2SO_4$+ KSCN electrolyte. With proper adjustment of elect rolyte composition, the contribution from intergranular corrosion, as a result of chromium carbide precipitation along the grain boundaries, can be distingui shed from the matrix and localized corrosion for the sensitized Alloy 600.

• 동의생리병리학회지
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• 제21권2호
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• pp.462-467
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• 2007

The radix of Pueraria thunbergiana BENTHAM (Leguminosae) is traditionally prescribed to attenuate the clinical manifestations of inner ear dysfunction and various clinical situations including fever, gastrointestinal disorders, skin problems, migraine headaches, lowering cholesterol and treating chronic alcoholism in Oriental Medicine. In the present study, we examined the effect of ethanol extract of P. thunbergiana radix (EPR) on cisplatin-mediated HEI-OC1 auditory cell death. In addition, to investingate the protection mechanism of EPR on free radicals. Treatment of EPR protected cells from cisplatin and reduced lipid peroxidation in a dose-dependent manner. Furthermore, EPR demonstrated significant scavenging activity against various free radicals, including superoxide radical, hydroxyl radical, hydrogen peroxide, and DPPH radical. These results indicate that EPR protects cisplatin-induced damages of HEI-OC1 cells through inhibition of lipid peroxidation and augmenting scavenging activities against free radials.

• 대한의용생체공학회:의공학회지
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• 제37권1호
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• pp.46-52
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• 2016

나노 입자는 암의 조기 진단과 효과적인 치유를 위한 약물 전달체 또는 영상 조영제로 연구개발 되어왔다. 이러한 나노 입자는 주로 EPR effect로 인해 효과적으로 암 세포를 표적하는 것이 가능하다고 보고되었고, 주로 구형의 나노 입자들이 이러한 실험에 적용되었다. 그러나 최근 EPR effect가 사람의 암 치료에 있어서는 큰 효과를 나타내지 않는다는 한계점이 여러 연구를 통해 제시되고 있다. 따라서 본 연구에서는 이러한 구형 나노 입자의 한계점을 극복하기 위한 새로운 형태의 디스크 나노 입자를 제안하고, 디스크 나노 입자의 생산 과정과 입자의 질을 향상시키기 위한 입자 생산방법에 관한 연구 내용을 보고하였다. 본 연구를 통해 생산된 디스크 나노 입자는 인간 유방암인 MCF7 세포에 적용하여 항암제 전달체로써의 가능성을 평가하였다.

• Macromolecular Research
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• 제16권1호
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• pp.15-20
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• 2008

The enhanced permeability and retention (EPR) effect is used extensively for the passive targeting of many macromolecular drugs for tumors. Indeed, the EPR concept has been a gold standard in polymeric anticancer drug delivery systems. This study investigated the tumoral distribution of self-assembled nanoparticles based on the EPR effect using fluorescein and radio-labeled nanoparticles. Self-assembled nanoparticles were prepared from amphiphilic chitosan derivatives, and their tissue distribution was examined in tumor-bearing mice. The size of the nanoparticles was controlled to be 330 run, which is a size suited for opening between the defective endothelial cells in tumors. The long-circulating polymer nanoparticles were allowed to gradually accumulate in the tumors for 11 days. The amount of nanoparticles accumulated in the tumors was remarkably augmented from 3.4%ID/g tissue at 1 day to 25.9%ID/g tissue at 11 days after i.v. administration. The self-assembled nanoparticles were sustained at a high level throughout the 14 day experimental period, indicating their long systemic retention in the blood circulation. The ${\gamma}$-images provided clear evidence of selective tumor localization of the $^{131}I$-labeled nanoparticles. Confocal microscopy revealed the fluorescein-labeled nanoparticles to be preferentially localized in the perivascular regions, suggesting their extravasation to the tumors through the hyperpermeable angiogenic tumor vasculature. This highly selective tumoral accumulation of nanoparticles was attributed to the leakiness of the blood vessels in the tumors and their long residence time in the blood circulation.

• 대한기계학회논문집B
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• 제32권8호
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• pp.567-573
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• 2008

The conventional refrigeration system is composed of a compressor, condenser, receiver, expansion valve or capillary tube, and an evaporator. The refrigeration system used in this study has additional expansion valve and evaporator along with an evaporation pressure regulator(EPR) at the exit side of the evaporator. The two evaporators can be operated at different temperatures according to the opening of the EPR. The experimental results obtained using the refrigeration system with parallel control of evaporation pressure are presented and the performance analysis of the refrigeration system with two evaporators is conducted.

• Bulletin of the Korean Chemical Society
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• 제23권12호
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• pp.1769-1772
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• 2002

Previous $^{19}F\;and\;^{1,2}H$ electron-nuclear double resonance (ENDOR) study of fluorometmyoglobin (MbF) in frozen-solution state provided sensitive tools sensing subtle structural changes of the heme that are not obtainable from X-ray. [Fann et al., J. Am. Chem. Soc. 1995, 117, 6019] Because of the intrinsic inhomogeneouse EPR line broadening effect of MbF in frozen-solution state, detection of the intrinsic inhomogeneouse EPR line broadening effect of MbF in frozen-solution state, detection of the electronic and geometrical changes of the heme ring itself and the proximal histidine by using $^{14}N$ CW ENDOR was interfered. In the present study, hyperfine-sensitive $^{14}N$ Mims ENDOR technique of pulsed-EPR was employed to probe the changes. With two different $\tau$ values of 128 and 196 ns, $^{14}N$ ENDOR signals of the heme and proximal histidine were completely resolved at $g'_{II}(=g_e=2)$. This study present that X-band $^{14}N$ Mims ENDOR sequence can sensitively detect the small changes of the spin densities and p orbital populations of the proximal and the heme nitrogens, caused by ligand and pH variation of the distal site.

• Animal Bioscience
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• 제34권4호
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• pp.724-733
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• 2021

Objective: The objectives of this study were to investigate the direct antioxidative effect of 90 Kda heat shock protein (Hsp90) obtained from duck muscle. Methods: The interaction of Hsp90 with phospholipids and oxidized phospholipids was studied with surface plasmon resonance (SPR), and their further oxidation in the presence of Hsp90 was evaluated with thiobarbituric acid reactive substances (TBARS) assay. The scavenging effect on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis (3-ethylbenzthiazoline-6-sulfonic acid (ABTS) was measured, and the electron paramagnetic resonance (EPR) spectroscopy in combination with 5-tert-Butoxycarbonyl-5-methyl-1-pyrroline-N-oxide and 2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) was utilized to determine the abilities of Hsp90 in scavenging hydroxyl and PTIO radicals. Results: SPR showed Hsp90 could bind with both phospholipids and oxidized phospholipids, and prevent their further oxidation by the TBARS assay. The DPPH and ABTS scavenging activity increased with Hsp90 concentration, and could reach 27% and 20% respectively at the protein concentration of 50 μM. The EPR spectra demonstrated Hsp90 could directly scavenge ·OH and PTIO· radicals. Conclusion: This suggests that Hsp90, a natural antioxidant in meat, may play an important role in cellular defense against oxidative stress, and may have potential use in meat products.

• 한국식품영양과학회지
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• 제35권1호
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• pp.28-34
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• 2006

갈근(Puerariae Radix)의 $70\%$ ethanol 추출물 중 ethyl acetate 분획물(EPR)은 염증성 cytokine을 처리한 마우스 대식세포 및 토기 연골조직세포에서 염증의 발현과 관련된 NO 생성 저해효과를 보였고, 관절조직의 주요 성분 중 하나인 proteoglycan의 분해 억제효과와 관절조직 분해효소인 MMP-9의 활성이 억제되었다. 또한, 통증유발물질인 프로스타글란딘의 유의성 있는 감소를 보여 통증억제 효과가 있음을 확인하였을 뿐만 아니라 초산 유발 진통 효과테스트인 동물 모델에서도 효과적으로 통증을 억제함을 확인하였다. 즉, 갈근의 $70\%$ ethanol 추출물 중 ethyl acetate 분획물(EPR)은 독성의 문제뿐만 아니라, 소염, 진통 효과 및 연골 조직세포의 분해를 억제하는 다양한 효과를 나타내는 장점을 지니고 있어 관절염 치료제의 훌륭한 후보약재가 될 것으로 기대된다.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.133.2-134
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• 2003

The major hurdle of conventional chemotherapeutics is the toxicity to normal tissue. The possible therapeutic advantage(s) of nano-particle encapsulated chemotherapeutics (nano-molecules) may be the enhanced permeability and retention (EPR) effect. Nano-molecules with increase volume may incorporated into the tumor tissue selectively, which is composed of rather sparse structure. EPR effect may cause of increased effectiveness with lower tixicity to normal tissue of nano-chemotherapeutics. (omitted)