• Korean Journal of Food Science and Technology
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• v.24 no.4
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• pp.341-346
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• 1992

The antimutagenic effects of enzymatic browning reaction products (MEBRPs) of polyphenol compounds (catechol, homocatechol, hydroxyhydroquinone, pyrogallol) by enzyme extracted from mushroom (Agaricus bisporus) were demonstrated through spore rec-assay using B. subtilis $H17(rec^+)$ and $M45(rec^-)$, Ames test using S. typhimurium TA98 and TA100 and SOS chromotest using E. coli PQ37/plasmid pKM101. In spore rec-assay, the MEBRPs showed antimutagenic effects by decreasing of the inhibition zone induced by MNNG. In Ames test with S-9mix in both TA98 and TA100, all of MEBRPs showed strong antimutagenic effects of about 21 to 99% against mutation by $B({\alpha})P$ and Trp-P-1, as adding $300\;{\mu}l$ of the MEBRPs. In SOS chromotest, MEBRPs showed antimutagenic effects by inhibiting the SOS-inducing function induced by 4NQO and MMC, as increasing in concentration of the MEBRPs. But they did not showed mutagenicity in these bacterial assays.

• Animal cells and systems
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• v.3 no.2
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• pp.229-236
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• 1999

The recA gene plays a central role in genetic recombination and SOS DNA repair in Escherichia coli (E. coli). We have previously identified a 42 kDa RecA-like protein inducible by a variety of DNA damages from a fluorescent Pseudomonas strain sp. and characterized its inducible kinetics. In the present study, we cloned and characterized the gene encoding the RecA-like protein by immunological screening of Pseudomonas genomic expression library using polyclonal E. coli anti-RecA antibodies as a probe. From 10$^{5}$ plaques screened, five putative clones were finally isolated. Southern blot analysis indicated that four clones had the same DNA inserts and the recA-like gene was located within the 3.2 kb EcoRI fragment of Pseudomonas chromosomal DNA. In addition, the cloned recA-like gene was transcribed into an RNA transcript approximately 1.1 kb in size, as judged by Northern blot analysis. The cellular level of RNA transcript of the cloned recA-like gene was increased to an average of 5.15- fold upon treatment with DNA damaging agents such as ultraviolet (UV)- light, nalidixic acid (NA), methyl methanesulfonate (MMS), and mitomycin-C (MMC). These results suggest that the cloned gene is inducible by DNA damage similarly to the recA gene in E. coli. However, the cloned gene did not restore the DNA damage sensitivity of the E. coli recA-mutant.

• Korean Journal of Food Science and Technology
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• v.26 no.2
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• pp.188-194
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• 1994

The inhibitory effects of rice extract on mutagenicity induced by 3-amino-1,4-dimethyl-5H-pyrido [4,3-b]indole(Trp-P-1), 3-amino-1-methyl-5H-pyrido [4,3-b]indole(Trp-P-2), sodium azide(SA), 2-nitrofluorene(2NF), mitomycin C(MMC), aflatoxin $B_1(AFB_1)$ and 4-nitroquinoline oxide(4-NQO) were investigated using Salmonella typhimurium reversion assay, SOS chromotest and spore rec-assay. In Salmonella typhimurium reversion assay, methanol extract from brown rice (Illpumbyeo, Japonica variety) showed the highest inhibitory effect among other extracting solvent including hexane, chloroform and water. Methanol extract showed stronger inhibitory effect, above 85%, on indirect-acting mutagens(Trp-P-1, Trp-P-2 and $AFB_1$) than those on direct-acting mutagens(4-NQO, 2NF). In SOS chromotest, methanol extracts showed $77.6{\sim}88.9%$ effects on SOS function induced by Trp-P-1, Trp-P-2, $AFB_1$ and 4-NQO. In spore rec-assay, methanol extracts inhibited the mutagenicity induced by $AFB_1$ and MMC. As the concentration of methanol extract increased, inhibitory effect on mutagenicity increased but reached at steady state as inhibition rate of 90% when the concentration was above 5 mg/plate. In inhibitory effects of methanol extracts by various rice varieties, all of 11 varieties turned out to have inhibitory effect on mutagenicity. There was no significant difference (p>0.05) in inhibitory effect of methanol extracts between brown and white rice against Trp-P-1, but showed difference (p<0.05) against 4-NQO.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.3
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• pp.139-147
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• 2017

In recent years, non-volatile memory express (NVMe), a new host controller interface standard, has been adapted to overcome performance bottlenecks caused by the acceleration of solid state drives (SSD). Recently, performance breakthrough cases over AHCI based SATA SSDs by adapting NVMe based PCI Express (PCIe) SSD to servers and PCs have been reported. Furthermore, replacing legacy eMMC-flash storage with NVMe based storage is also considered for next generation of mobile devices such as smartphones. The Linux kernel includes drivers for NVMe support, and as the kernel version increases, the implementation of the NVMe driver code has changed. However, mobile devices are often equipped with older versions of Android operating systems (OSes), where the newest features of NVMe drivers are not available. Therefore, different features of different NVMe driver implementations are not well evaluated on Android OSes. In this paper, we analyze the response time of the NVMe driver for various Linux kernel version.

• Parasites, Hosts and Diseases
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• v.36 no.2
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• pp.109-120
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• 1998

Mucosal mast cell (MMC) and goblet cell (GC) responses were observed in the small intestine of two strains of mice (BALBfc and C3H) infected with Weodiplostomum seouLehTe, and their roles in the host defense and worm expulsion were studied. From day 3 to 28 post-infection (Pl) with 200 metacercariae, the worm recovery rate from BALB/c mice was consistently and remarkably higher than that from C3H mice. In the duodenum of both strains of mice, the main habitat of the flukes, mastocytosis was pronounced on day 7 Pl but quickly diminished thereafter. Similar kinetics were observed in the jejunum and ileum, although the extent of mastocytosis was lesser in the ileum than other two areas. These MMC kinetics were not different between the ko strains of mice. Moreover, the extent of mastocytosis was stronger in BALB/C mice than in C3H mice. GC hyperplasia was remarkable in the duodenum of BALBlc mice throughout the course of infection except day 14 Pl, whereas it was recognizable only in the jejunum and ileum of C3H mice on day 7 Pl. Mucin activation was evidently demonstrated in both strains of mice throughout the course of infection, but more marked in BALB/c than in C3H mice. The results strongly suggest that mastocytosis and GC hyperplasia are local immune responses against N. seoulense, however, they play a minor role in the host defense and worm expulsion.

• Korean Journal of Materials Research
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• v.18 no.6
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• pp.339-346
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• 2008

Single-crystal $ZnIn_2S_4$ layers were grown on a thoroughly etched semi-insulating GaAs (100) substrate at $450^{\circ}C$ with a hot wall epitaxy (HWE) system by evaporating a $ZnIn_2S_4$ source at $610^{\circ}C$. The crystalline structures of the single-crystal thin films were investigated via the photoluminescence (PL) and Double-crystal X-ray rocking curve (DCRC). The temperature dependence of the energy band gap of the $ZnIn_2S_4$ obtained from the absorption spectra was well described by Varshni's relationship, $E_g(T)=2.9514\;eV-(7.24{\times}10^{-4}\;eV/K)T2/(T＋489K)$. After the as-grown $ZnIn_2S_4$ single-crystal thin films was annealed in Zn-, S-, and In-atmospheres, the origin-of-point defects of the $ZnIn_2S_4$ single-crystal thin films were investigated via the photoluminescence (PL) at 10 K. The native defects of $V_{Zn}$, $V_S$, $Zn_{int}$, and $S_{int}$ obtained from the PL measurements were classified as donor or acceptor types. Additionally, it was concluded that a heat treatment in an S-atmosphere converted $ZnIn_2S_4$ single crystal thin films into optical p-type films. Moreover, it was confirmed that In in $ZnIn_2S_4$/GaAs did not form a native defects, as In in $ZnIn_2S_4$ single-crystal thin films existed in the form of stable bonds.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.155-160
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• 2002

Metal matrix composites had generated a lot of interest in recent times because of significant in specific properties. It was also highlighted as the materials of frontier industry because strength, heat-resistant, corrosion-resistant, wear-resistant were superiored. In this study the strength properties of $Al_{18}B_4O_{33}/AC4CH$ were represented mixing the binder of $Al_2O_3$ and $TiO_2$. It was also fabricated by squeeze casting. $Al_{18}B_4O_{33}/AC4CH$ was fabricated at the melt temperature of $760^{\circ}C$ the perform temperature of $700^{\circ}C$ and mold temperature of $200^{\circ}C$ under the pressure of 83.4MPa and observed SEM. Fatigue crack growth rate tests on compact tension specimen(half-size) of thickness 12.5mm were conducted by using sinusoidal waveform. Compact tension specimens(half-size) were used and fatigue crack growth rate da/dN and stress intensity factor range ${\Delta}K$ were analyzed concerning to the R value of 0.1 and 0.05. In order to find out the value of ${\Delta}K$, load amplitude constant method was applied by the standard fatigue testing method describes in ASTM E647-95a. As the results of this study, Fatigue crack growth rate increased with in creasing the load ratio, Consequently, At equivalent stress intensity factors, the fatigue crack growth rates in MMC were faster than those of AC4CH alloy. then the fatigue life and the fatigue crack growth rate was investigated using scanning election microscopy(SEM)

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.11
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• pp.3474-3490
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• 1996

A metal matrix composites(MMCs) for A16061 reinforced with silicon carbide particles is fabricated by melt-stirring method. The primary products of MMCs billets are prepared by volume fractions 5 vol% to 20 vol% and particle size $13\mu m$ to $22\mu m$.This paper will be made to examine the microstructure and mechanical properties of fabricated $SiC_p$/Al 6061 composite by melt-stirring and squeeze casting method. The MMC billets is extruded at $500^{\circ}C$ under the constant extrusion velocity $V_e$=2mm/min using curved shape die. Extrusion force, particle rearrangement, micro structure and mechanical properties of extruded composites will be investigated. The mechanical properties of primary billets manufactured by melt-stirring and squeeze casting method will be compared with extrusion specimen. The effect of volume fraction and size of the reinforcements will be studied. The increase in uniformity of particle dispersion is the major reason for an improvement in reliability due to hot extrusion with optimal shape die. Experimental Young's modulus and 0.2% offset yield strength for the extruded MMCs will be compared with theretical values calculated by the Eshelby method. A method will be proposed for the prediction of Young's modulus and yield strength in $SiC_p$ reinforced MMCs.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.105-110
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• 2000

The Micromechanics test is new test method which uses comparatively smaller specimen than that required in conventional material tests. There are several methods, such as small-specimen creep test, the continuous indentation test, and small punch(SP) test. Among them, the small punch(SP) test method has been applied to many evaluation fields, such as a ductile-brittle transition temperature, stress corrosion cracking, hydrogen embrittlement, and fracture properties of advanced materials like FGM or MMC. In this study, the small punch(SP) test is performed to evaluate the mechanical properties at high/low temperature from $-196^{\circ}C$ to $650^{\circ}C$ and the material degradation for virgin and aged materials of 9Cr1MoVNb steel which has been recently developed. The ${\Delta}P/{\Delta}{\delta}$ parameter defined a slope in plastic membrane stretching region of SP load-displacement curve decreases according to the increase of specimen temperature, and that of aged materials is higher than the virgin material in all test temperatures. And the material degradation degrees of aged materials with $630^{\circ}C$ -500hrs and $630^{\circ}C$ -1000hrs are $36^{\circ}C$ and $38^{\circ}C$ respectively. These behaviors are good consistent with the results of hardness($H_v$) and maximum displacement(${\delta}_{max}$).

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.8
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• pp.3447-3450
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• 2015

Objective: To explore the sensitivity of gastric cancer cells to chemotherapy drugs in elderly patients and its correlation with cyclooxygenase-2 (COX-2) expression in cancer tissue. Materials and Methods: Forty-three elderly patients with gastric cancer (observation group) and 31 young patients with gastrointestinal tumors (control group) who were all diagnosed by pathology and underwent surgery in the 89th Hospital of Chinese People's Liberation Army were selected. Drug sensitivity testing of tumor cells in primary culture was carried out in both groups using a methyl thiazolyl tetrazolium (MTT) method, and the expression of COX-2 and the factors related to multi-drug resistance (MDR) in cancer tissue were assessed by immunohistochemistry. Results: The inhibition rates (IR) of vincristine (VCR), 5-fluorouracil (5-FU), oxaliplatin (L-OHP), mitomycin (MMC) and epirubicin (eADM) on tumor cells in the observation group were dramatically lower than in the control group, with statistical significance (P<0.05 or P<0.01). The positive rates of COX-2, glutathione s-transferase-${\pi}$ (GST-${\pi}$) and P glycoprotein (P-gp) expression in cancer tissue in the observation group were all higher than in control group (P<0.05), while that of DNA topoisomerase $II{\alpha}$ ($TopoII{\alpha}$) expression lower than in the control group (P<0.01). In the observation group, COX-2 expression in cancer tissue had a significantly-positive correlation with GST-${\pi}$ and P-gp (r=0.855, P=0.000; r=0.240, P=0.026), but a negative correlation with $TopoII{\alpha}$ (r=-0.328, P=0.002). In the control group, COX-2 expression in cancer tissue was only correlated with P-gp positively (r=0.320, P=0.011). Bivariate correlation analysis displayed that COX-2 expression in cancer tissue in the observation group had a significantly-negative correlation with the IRs of 5-FU, L-OHP, paclitaxel (PTX) and eADM in tumor cells (r=-0.723, P=0.000; r=-0.570, P=0.000; r=-0.919, P=0.000; r=-0.781, P=0.000), but with hydroxycamptothecine (HCPT), VCR and 5-FU in the control group (r=-0.915, P=0.000; r=-0.890, P=0.000; r=-0.949, P=0.000). Conclusions: Gastric cancer cells in elderly patients feature stronger MDR, which may be related to high COX-2 expression.