• 한국자기학회지
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• 제14권5호
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• pp.169-173
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• 2004

$\alpha$-F $e_2$ $O_3$, 나노 입자를 균일한 크기로 제조하여 Morin 전이 온도( $T_{M}$)를 전 후로 스핀의 변화에 관하여 연구하였다. X-선 회절 분석과 입도분포 측정을 통하여 입자는 80nm정도의 매우 군일한 크기 분포를 하고 있음을 확인하였다. Mossbauer 분광기를 통하여 4.2K에서부터 실내온도까지 여러 온도 범위에 걸쳐 측정한 결과 입자의 크기에 따라 $T_{M}$온도가 변화되었고 스핀의 상태 역시 달라졌다. $T_{M}$은 $b_{ulk}$상태에서 265 K의 값을 가지고 있으나 입자의 크기가 작아질수록 낮아지고, 임계 크기 이하에서는 전이가 전혀 일어나지 않는다. 80nm크기의 입자에서, 스핀의 방향은 $T_{M}$ 이상의 온도에서는 정상적으로 hexagonal구조의 c축에 90$^{\circ}$ 이루고 있으나 $T_{M}$ 이하의 온도에서는 c 축에 나란하지 않고 일정한 각(28$^{\circ}$～29$^{\circ}$)을 유지하는데, 이 방향은 rhombohedral구조의 [110]에 해당하는 것으로 지금까지 알려진 0$^{\circ}$와 90$^{\circ}$사이의 스핀 전이와는 다른 모습을 보여주고 있다.

• 한국언어정보학회:학술대회논문집
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• 한국언어정보학회 1996년도 Language, Information and Computation = Selected Papers from the 11th Pacific Asia Conference on Language, Information and Computation, Seoul
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• pp.11-20
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• 1996

• Journal of Magnetics
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• 제15권1호
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• pp.21-24
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• 2010

A new synthetic method for the formation of uniform $\alpha-Fe_2O_3$ nanoparticles was reported and their magnetic properties were investigated. The sonochemical synthesis and the subsequent take-off technique resulted in spherical shaped $\alpha-Fe_2O_3$ nanoparticles with an average diameter of 60 nm. The temperature- and applied magnetic field-dependent magnetization of the $\alpha-Fe_2O_3$ nanoparticles was explained by the sum of two contributions, i.e., the Morin transition and superparamagnetism, because the critical size for superparamagnetism was within the size variation of the nanoparticles.

• 대한화학회지
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• 제36권6호
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• pp.889-893
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• 1992

Ga-Morin 착물에 대한 흡착벗김전압전류법적 연구를 HMDE를 사용하여 0.1M 아세테이트 완충용액에서 연구하였다. HMDE의 수은 표면에 흡착된 착물의 환원피크 전류에 미치는 여러 분석조건들의 영향을 논의하였으며, 여러 양이온 및 계면활성제의 방해효과에 대하여 검토하였다. 본 연구에서의 검출한계는 흡착시간이 60초일 때 1.7nM 이었으며, 4 ${\mu}$g/l의 Ga를 7회 분석하였을 때 상대표준편차 2.8% 이었다.

• Bulletin of the Korean Chemical Society
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• 제9권2호
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• pp.106-108
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• 1988

The effects of surfactants, CTAB, SDS, and TX-100, on the fluorescence emission intensity of Be-morin complex was studied in terms of pH, temperature, added electrolyte, and concentration of surfactants. The ionic surfactants decreased the fluorescence intensity of the complex. However, the addition of TX-100 caused a substantial increase in the fluorescence intensity without spectral shift, by which means the detection limit of Be was obtained to be 0.3 ppb. Optimum pH for Be determination was near 9.6 and the fluorescence intensity showed a continuous decline with the increase of temperature. Nitrate ion lowered the fluorescence intensity considerably. Mechanism of the interference remains to be elucidated.

• Nutritional Sciences
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• 제5권4호
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• pp.197-202
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• 2002

We compared the radical scavenging activity of flavonoids and their antioxidant effects on erythrocyte Na leak, platelet aggregation and TBARS (thiobarbituric acid reactive substance) production, using Sprague Dawley rats. The concentrations of flavonoids needed for scavenging radicals by 50% ($SC_{50}$) in 0.1mM DPPH (2,2 Diphenyl 1-picryl hydrazyl) were: Quercetin, 7.4/$\mu$M; Catechin, 10.6$\mu$M; Morin, 22$\mu$M; Hesperidin, 400uM; and Naringin, 3.95mM. Morin completed its antioxidant activity in 2 minutes, while catechin, hesperidin and naringin had slow but long lasting antioxidant activity. Whole blood platelet aggregation, when incubated with quercetin or catechin, was significantly decreased (P<0.05) compared with the control. Sodium leak in intact erythrocytes was significantly lower when incubated with quercetin, compared with other flavonoids (P<0.05). Morin, hesperidin and naringin somewhat increased Na leak in intact erythrocytes. Sodium leak in erythrocytes treated with phenazine methosulfate (PMS) was increased overall, but was not affected by flavonoids. Intracelluar Na and K were not affected by treatment with PMS. TBARS production in platelet rich plasma (PRP) was significantly lower (P<0.05) than the control when incubated with quercetin or hesperidin. PMS treatment caused an increase in TBARS production regardless of flavonoids. In the present study antioxidant effects of flavonoids were not well correlated with their radical scavenging activities, although quercetin, which showed the strongest radical scavenging activity, had the greatest antioxidant effect.

• Journal of Pharmaceutical Investigation
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• 제35권4호
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• pp.249-254
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• 2005

Multidrug resistance (MDR) of cancer cells is, at least in part, associated with the overexpression of P-glycoprotein (P-gp). Many studies have demonstrated that natural compounds obtained from fruits, vegetables, teas and medicinal plants may modulate P-gp activity. The objective of the present investigation was to examine the effect of seven natural compounds on the P-gp activity in human uterine sarcoma cell line, MES-SA/DX5. Daunomycin uptake was significantly increased by biochanin A and silymarin (p<0.0001) whereas it was reduced by morin (p<0.01). The efflux of daunomycin from the cells was significantly inhibited by biochanin A, morin, cephalotaxine, berberine (p<0.05) and silymarin (p<0.0001). Biochanin A, berberine and silymarin significantly decreased $IC_{50}$ value of daunomycin (p<0.05) while morin increased it (p<0.05). These results suggest that some natural compounds such as biochanin A and silymarin may inhibit P-gp function and can be developed as MDR reversing agents to improve the efficacy of chemotherapeutic drugs when administered concomitantly.

• 한국자기학회지
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• 제11권1호
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• pp.21-25
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• 2001

Si 기판 위에 $\alpha$-Fe$_2$O$_3$ 박막을 pulsed laser deposition system으로 제조하여 결정학적 및 자기적 성질을 X선 회절 및 Mossbauer 분광법을 사용하여 연구하였다. 박막의 제조조건은 laser의 출력 5.128 W/$cm^2$, 산소의 압력 0.1 torr, 기판의 온도 30$0^{\circ}C$에서 가장 이상적이었으며 이를 공기 중 80$0^{\circ}C$에서 1일간 열처리하였다. 입자는 크기는 길이 200~300nm, 폭 70-150 nm정도의 타원체로 기판에 비스듬히 누운 형태를 취하고 있으며 결정은 육방정계 형태의 corundum 구조로서 결정상수는 a = 5.03 0.05 $\AA$, c = 13.73$\pm$0.05 $\AA$로 측정되었다. 원자의 스핀 방향은 감마선 방향(기판에 수직 방향)에 대하여 평균적으로 Morin 변환 이하에서는 38$^{\circ}$, 그 이상에서는 48$^{\circ}$의 각을 이루며 특정한 방향을 선호하고있는 것으로 나타났다. Morin 변환은 200 K에서 실온가지 넓은 온도 범위에서 일어나며, c-축에 대한 원자의 스핀 방향은 48$^{\circ}$에서 80$^{\circ}$정도의 변화만이 관측되었다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1996년도 춘계학술대회
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• pp.188-188
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• 1996

In order to gain insight into the mechanism of the regulation of cytochrome P450IAl by arylhydrocarbon, the 5'-flanking region of a trout CYP450IAl 5'flanking DNA was cloned into pCAT-basic vector and it was transfected into Hepa-1 cells. 3MC treatment to hepa Ⅰ cells transfected with fish CYP450IAl-CAT construct results in mRNA increased by 2.81 fold when it was compared with that of control This increase of mRNA was decreased by concomitantly treated flavonoids such as morin. The levels of CAT mRNA that was treated with morin was 29.2-58.0% of 3MC stimulated CAT mRNA. Further investigation to find out if there are DRE, XRE or negative regulatory cis element in CYP450IA1 gene was undertaken. Results of the deletion study of 5'flanking DNA of trout P450IA indicate the existance of the negative(-1600 ～ -1300). CAT mRNA was about two-fold higher in deleted trout CYP450IAl-CAT construct transfected cells compared to the wi Id type trout CYP450IAl-CAT construct transfected cells. And The stimulatory effect of 3MC was no longer observed in col Is containing deleted CAT construct. [Supported by grants from the Korean Ministry of Education]

• Environmental Analysis Health and Toxicology
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• 제10권3_4호
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• pp.29-40
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• 1995

To investigate and evaluate the scavenging and antioxidative effects of various ftavonoids on paraquat induced pulmonary toxicity, in vivo and vitro tests of eight flavonoids(catechin, epicatechin, flayone, chrysin, apigenin, quercetin, morin and biochanin A) were carried out. In vitro test, inhibitory and antioxidative effects of lipoxygenase dependent lipidperoxidation, NADPH dependent cytochrome p-450 reductase to liver and lung microsome and superoxide anion production in rat peritoneal exudated macrophage were studied. In vivo test, biochemical parameters and cell population in bronchoalveolar lavage fluid(BALF) in mouse and rats after administration of paraquat and flavonoids were tested. The results are summerized as follows; 1. All flavonoids tested inhibited on NADPH dependent cytochrome p-450 reductase in liver and lung microsome. 2. All flavonoids tested showed the inhibitory effects on the superoxide anion production in rat peritoneal exudated macropharge. 3. Lactate dehydrogenase, acid phosphatase and total protein in BALF of mouse which increased by the administration of paraquat, decreased significantly by catechin, chrysin, morin and biochanin A. 4. Numbers of alveolar macropharge and PMN in BALF of rats which increased by the administration of paraquat decreased by all the tested flavonoids. Therefore, all flavonoids tested showed the useful compounds for scavenger and antioxidant on paraquat induced pulmonary toxicity.