• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.705-709
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• 2003

The microstructure and electrical properties of the $Pr_6O_{11}$-based ZnO varistor ceramics, which are composed of Zn-Pr-Co-Cr-Tb oxides, were investigated with $Tb_4O_7$ amount. The varistor ceramics exhibited very high densification based on increasing density in the range of $5.73{\sim}5.85g/cm^3$ as $Tb_4O_7$ amount is increased. The calculated nonlinear exponent( ${\alpha}$ ) in varistor ceramics without $Tb_4O_7$ was only 8.9, whereas the ${\alpha}$ value of the varistor ceramics with $Tb_4O_7$ was abruptly increased in the range of 18.6 to 42.0. In particular, the maximum value(42.0) of ${\alpha}$ was obtained by doping of 1.0 mol% $Tb_4O_7$. The measured leakage current($I_{\ell}$) in varistor ceramics without $Tb_4O_7$ was $40.1{\mu}A$, whereas the $I{\ell}$ value of the varistors with $Tb_4O_7$ was very abruptly decreased below $5{\mu}A$. It is estimated that $Tb_4O_7$ additives will is applied usefully in development of varistors possessing high performance.

• Korean Journal of Veterinary Research
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• v.29 no.2
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• pp.59-67
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• 1989

This paper deals with the genetic properties of R plasmids in Salmonella originated from pigs and cattle. The plasmid DNA was examined for incompatibility, stability and fertility inhibition(Fi), and gel electrophoresis was performed for isolation of plasmid DNA. The results obtained were summerized as follows: 1. Among the 66 conjugative R plasmids from 44 pigs and 22 cattle, 61 R plasmids (92.4%) were $Fi^-$, whereas the remainder were $Fi^+$. 2. The Inc groups of 66 R plasmids were determined with 7 standard plasmids. Twenty-six R plasmids were classified into Inc group $I{\alpha}$, H1, H2 or F1, 40 R plasmids being not classified with standard plasmids used, and the Inc group $I{\alpha}$ (57.7%) was most frequent. 3. Inc groups $I{\alpha}$, H1, and F1 were identified in strains from swine, Inc groups H2 and F1 from cattle. 4. The plasmid DNA profiles in 16 Salmonella isolated from pigs and cattle were confirmed as being 1 to 10 fragments by the gel eletrophoresis. Their molecular weight ranged 1.0 to 90 megadalton. 5. The molecular weight of conjugative plasmids ranged 1.0 to 80 megadalton in 4 Salmonella (P-4, P-5, P-7 and P-8) isolated from pigs.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.4
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• pp.244-252
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• 1994

The morphological changes of primary solid particles as a fuction of process time on Al-Si alloys during semi-solid state processing with a shear rate of 200s were studied. In hypereutectic Al-15.5wt%Si alloy, it was observed that primary Si crystals are fragmented in the early stage of stirring and morphologies of primary Si crystals change from faceted to spherical during isothermal shearing for 60 minutes. In quaternary Al-12.5wt%Si-2.9wt%Cu-0.7wt%Mg alloy system, it was observed both primary silicon and ${\alpha}$-alumunum particles. Microstructural evolution of primary Si crystals was similar to that of the hypereutectic Al-Si alloy but equiaxed ${\alpha}$-Al dendrites are broken into nearly spherical at the early stage of shearing and later stage of the isothermal shearing ${\alpha}$- Al particles are slightly coarsoned by Ostwald ripening. Mechanical properties of Al-Si-Cu-Mg alloy were compared to those from other processes (squeeze casting and gravity casting). After T6 heat treatment, comparable values of hardness were obtained while slightly lower compressive strength values were observed in rheocast alloy. The elongation, on the other hand, exhibited significant increasement of 15% over gravity cast alloy.

• Journal of Magnetics
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• v.15 no.1
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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.

• Honam Mathematical Journal
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• v.31 no.4
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• pp.591-599
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• 2009

For given ${\alpha},{\omega}\;{\in}\;{\mathbb{R}}$ and ${\beta}$ > 1, let $T_{{\beta},{\alpha},{\omega}}$ be the skew-product transformation on the torus, [0, 1) ${\times}$ [0, 1) defined by (x, y) ${\longmapsto}\;({\beta}x,y+{\alpha}x+{\omega})$ (mod 1). In this paper, we give a criterion of ergodicity and weakly mixing for the transformation $T_{{\beta},{\alpha},{\omega}}$ when the natural extension of the given ${\beta}$-transformation can be viewed as a generalized baker's transformation, i.e., they flatten and stretch and then cut and stack a two-dimensional domain. This is a generalization of theorems in [10].

• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1311-1317
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• 2021

In this study, an airborne alpha detection system, which consists of a passivated implanted planar silicon (PIPS) detector and an air filter, was developed. A collimator applied to the alpha detection system showed an enhancement in resolution and a degradation in detection efficiency. The resolution and detection efficiency were compared and analyzed to evaluate the performance of the collimator. Thus, the resolution was found to be more important than the efficiency as a determining factor of the detection system performance, from the viewpoint of radionuclide identification. The performance was evaluated on three properties of the collimator: hole shape, hole length, and the ratio between the hole and frame pitches. From the hole shape performance evaluation, a hexagonal collimator showed the highest resolution. Further, the collimator with a hole pitch of 14 mm was found to have the highest resolution while that with a frame pitch of 4-6 mm (i.e., 1.2-1.4 times longer than the hole pitch) showed the highest resolution.

• Korean Journal of Microbiology
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• v.29 no.6
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• pp.380-386
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• 1991

Three types of soluble cytochrome c were purified to homogeneity from Methylobacillus sp. strain SK1 which grows only on methanol. Cytochrome c-I was purified 58.5-fold in seven steps. Cytochrome c-II and c-III were purified 57.3- and 122.1-fold in eight steps, respectively. The molecular weights of the cytochrome c-I was determined to be 12,500, while those of the cytochrome c-II and c-III were 16,000. The isoelectric points of the c-I, c-II and c-III were found to be 8.8, 6.6, and 6.6 respectively. The spectrum of reduced cytochrome c-I showed .alpha.-, .betha.-, .gamma.-peaks at 551.4, 522.2, and 416.6nm. The peaks for c-II were found at 551.0, 521.6, and 416.5nm, while those for c-III were shown at 551.2, 521.8, and 416.0 nm. The spectra of oxidized cytochrome c-I, c-II, and c-III showed .gamma.-peak at 411.8, 409.0, and 410.2 nm, respectively. The absorption coefficients of .alpha.- and .gamma.-peak for c-I in the reduced state were determined as 47 and 197 $mM^{-1}$ $cm^{-1}$ , respectively. The coefficients of .alpha.- and .gamma.-peak for c-II were determined to be 43 and 137 $mM^{-1}$ $cm^{-1}$ , while those for c-III were 41 and 172 $mM^{-1}$ $cm^{-1}$ , respectively. The c-I and c-III were found to bind carbon monoxide.

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.127.2-127
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• 2002

• Nutrition Research and Practice
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• v.11 no.2
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• pp.90-96
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• 2017

BACKGROUND/OBJECTIVES: Although the antioxidative effects of lycopene are generally known, the molecular mechanisms underlying the anti-inflammatory properties of lycopene are not fully elucidated. This study aimed to examine the role and mechanism of lycopene as an inhibitor of inflammation. METHODS/MATERIALS: Lipopolysaccharide (LPS)-stimulated SW 480 human colorectal cancer cells were treated with 0, 10, 20, and $30{\mu}M$ lycopene. The MTT assay was performed to determine the effects of lycopene on cell proliferation. Western blotting was performed to observe the expression of inflammation-related proteins, including nuclear factor-kappa B ($NF-{\kappa}B$), inhibitor kappa B ($I{\kappa}B$), mitogen-activated protein kinase (MAPK), extracellular signal-related kinase (ERK), c-jun NH2-terminal kinase (JNK), and p38 (p38 MAP kinase). Real-time polymerase chain reaction was performed to investigate the mRNA expression of tumor necrosis factor ${\alpha}$ ($TNF-{\alpha}$), interleukin-1 beta ($IL-1{\beta}$), interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). Concentrations of nitric oxide (NO) and prostaglandin $E_2$ ($PGE_2$) were determined via enzyme-linked immunosorbent assays. RESULTS: In cells treated with lycopene and LPS, the mRNA expression of $TNF-{\alpha}$, $IL-1{\beta}$, IL-6, iNOS, and COX-2 were decreased significantly in a dose-dependent manner (P < 0.05). The concentrations of $PGE_2$ and NO decreased according to the lycopene concentration (P < 0.05). The protein expressions of $NF-{\kappa}B$ and JNK were decreased significantly according to lycopene concertation (P < 0.05). CONCLUSIONS: Lycopene restrains $NF-{\kappa}B$ and JNK activation, which causes inflammation, and suppresses the expression of $TNF-{\alpha}$, $IL-1{\beta}$, IL-6, COX-2, and iNOS in SW480 human colorectal cancer cells.

• Journal of Microbiology and Biotechnology
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• v.15 no.3
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• pp.519-524
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• 2005

An ${\alpha}$-L-rhamnosidase (EC 3.2.1.40.), which transforms quercitrin to quercetin, was purified from Fusobacterium K-60, a human intestinal anaerobic bacterium. The specific activity of the purified ${\alpha}$-L-rhamnosidase was 2.89 mol/min/mg protein. ${\alpha}$-L-Rhamnosidase, whose molecular size was 170 kDa by gel filtration, was composed of four subunits ($M_r$ 41,000 Da) with pI and optimal pH values of 5.2 and 5.5-7.0, respectively. The apparent $K_m$ and $V_{max}$ values for p-nitrophenyl-${\alpha}$-L-rhamnopyranoside and quercitrin were determined to be 0.057 mM and 3.4 mol/min/mg, and 0.077 mM and 5.0 mol/min/mg, respectively. This enzyme was strongly inhibited by $Cu^{2+},\;Mn^{2+}$, L-rhamnose, and p-chlormercuriphenylsulfonic acid. These findings suggest that the biochemical properties and substrate specificity of the purified enzyme are different from those of the previously purified ${\alpha}$-L-rhamnosidase. This is the first reported purification of quercitrin-hydrolyzing ${\alpha}$-L-rhamnosidase from intestinal bacteria.