• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.6
• /
• pp.441-445
• /
• 2013

ZnO nanowires on the a-, c- and m-plane oriented 4H-SiC substrates were grown by using a high temperature tube furnace. Ti/Au electrodes were deposited on ZnO nanowires and a-, c- and m-plane 4H-SiC substrates, respectively. The shape and density of the ZnO nanowires were investigated by field emission scanning electron microscope. It was found that the growth direction of nanowires depends strongly on growth parameters such as growth temperature and pressure. In this work, The sensitivity of nanowires formed a-, c- and m-plane oriented 4H-SiC gas sensor was measured at $300^{\circ}C$ with CO gas concentration of 80%. The nanowires grown on a-plane oriented 4H-SiC show improved sensing performance than those on c- and m-plane oriented 4H-SiC due to the increased density of nanowire on a-plane 4H-SiC.

• Biomolecules & Therapeutics
• /
• v.27 no.6
• /
• pp.577-583
• /
• 2019

Human cytochrome P450 2C9 is a highly polymorphic enzyme that is required for drug and xenobiotic metabolism. Here, we studied eleven P450 2C9 genetic variants-including three novel variants F69S, L310V, and Q324X-that were clinically identified in Korean patients. P450 2C9 variant enzymes were expressed in Escherichia coli and their bicistronic membrane fractions were prepared The CO-binding spectra were obtained for nine enzyme variants, indicating P450 holoenzymes, but not for the M02 (L90P) variant. The M11 (Q324X) variant could not be expressed due to an early nonsense mutation. LC-MS/MS analysis was performed to measure the catalytic activities of the P450 2C9 variants, using diclofenac as a substrate. Steady-state kinetic analysis revealed that the catalytic efficiency of all nine P450 2C9 variants was lower than that of the wild type P450 2C9 enzyme. The M05 (R150L) and M06 (P279T) variants showed high $k_{cat}$ values; however, their $K_m$ values were also high. As the M01 (F69S), M03 (R124Q), M04 (R125H), M08 (I359L), M09 (I359T), and M10 (A477T) variants exhibited higher $K_m$ and lower $k_{cat}$ values than that of the wild type enzyme, their catalytic efficiency decreased by approximately 50-fold compared to the wild type enzyme. Furthermore, the novel variant M07 (L310V) showed lower $k_{cat}$ and $K_m$ values than the wild type enzyme, which resulted in its decreased (80%) catalytic efficiency. The X-ray crystal structure of P450 2C9 revealed the presence of mutations in the residues surrounding the substrate-binding cavity. Functional characterization of these genetic variants can help understand the pharmacogenetic outcomes.

• Microbiology and Biotechnology Letters
• /
• v.16 no.5
• /
• pp.393-397
• /
• 1988

The adenylate kinase was purified from an extreme thermophile by adenosine-pentaphospho-adenosine elution from phosphocellulose column. The molecular weight was estimated to be 22,000 by SDS-PAGE and gel filtration. The optimum temperature of the enzyme activity was 8$0^{\circ}C$ and the activation energy was given as 22.4 kcal/mole. The enzyme even showed full activity after incubation at 9$0^{\circ}C$ or in 6M guanidine-HCI at 3$0^{\circ}C$ and retained 75% of its original activity even after 1 hour at 10$0^{\circ}C$. The Michaelis constants of the enzymes for AMP, ADP, and ATP were 0.01mM, 0.017mM and 0.067mM, respectively.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.9
• /
• pp.5495-5501
• /
• 2013

Background: Alu elements are one of the most common repetitive sequences that now constitute more than 10% of the human genome and potential targets for epigenetic alterations. Correspondingly, methylation of these elements can result in a genome-wide event that may have an impact in cancer. However, studies investigating the genome-wide status of Alu methylation in cancer remain limited. Objectives: Oral squamous cell carcinoma (OSCC) presents with high incidence in South-East Asia and thus the aim of this study was to evaluate the Alu methylation status in OSCCs and explore with the possibility of using this information for diagnostic screening. We evaluated Alu methylation status in a) normal oral mucosa compared to OSCC; b) peripheral blood mononuclear cells (PBMCs) of normal controls comparing to oral cancer patients; c) among oral epithelium of normal controls, smokers and oral cancer patients. Materials and Methods: Alu methylation was detected by combined bisulfite restriction analysis (COBRA) at 2 CpG sites. The amplified products were classified into three patterns; hypermethylation ($^mC^mC$), partial methylation ($^uC^mC+^mC^uC$), and hypomethylation ($^uC^uC$). Results: The results demonstrate that the $%^mC^mC$ value is suitable for differentiating normal and cancer in oral tissues (p=0.0002), but is not significantly observe in PBMCs. In addition, a stepwise decrease in this value was observed in the oral epithelium from normal, light smoker, heavy smoker, low stage and high stage OSCC (p=0.0003). Furthermore, receiver operating characteristic (ROC) curve analyses demonstrated the potential of combined $%^mC$ or $%^mC^mC$ values as markers for oral cancer detection with sensitivity and specificity of 86.7% and 56.7%, respectively. Conclusions: Alu hypomethylation is likely to be associated with multistep oral carcinogenesis, and might be developed as a screening tool for oral cancer detection.

• Korean Journal of Materials Research
• /
• v.12 no.5
• /
• pp.414-422
• /
• 2002

Three different multi-component white cast irons alloyed with Cr, V, Mo and W were prepared in order to study their as-cast and solidification structures. Three combinations of the alloying elements were selected so as to obtain the different types of carbides and matrix structures : 3%C-10%Cr-5%Mo-5%W(alloy No.1), 3%C-10%V-5% Mo-5%W(alloy No. 2) and 3%C-17%Cr-3% V(alloy No.3). The as-cast microstructures were investigated with optical and scanning electron microscopes. There existed two different types of carbides, $M_7C_3$ carbide with rod-like morphology and $M_6C$ carbide with fishbone-like one, and matrix in the alloy No. 1. The alloy No. 2 consisted of MC carbide with chunky and flaky type and needle-like $M_2C$ carbide, and matrix. The chunky type referred to primary MC carbide and the flaky one to eutectic MC carbide. The morphology of the alloy No. 3 represented a typical hypo-eutectic high chromium white cast iron composed of rod-like $M_7C_3$ carbide which is very sensitive to heat flow direction and matrix. To clarify the solidification sequence, each iron(50g) was remelted at 1723K in an alumina crucible using a silicon carbide resistance furnace under argon atmosphere. The molten iron was cooled at the rate of 10K/min and quenched into water at several temperatures during thermal analysis. The solidification structures of the specimen were found to consist of austenite dendrite(${\gamma}$), $ ({\gamma}+ M_7C_3)$ eutectic and $({\gamma}+ M_6C)$ eutectic in the alloy No. 1, proeutectic MC, austenite dendrite(${\gamma}$), (${\gamma}$+MC) eutectic and $({\gamma}+ M_2C)$ eutectic in the alloy No. 2, and proeutectic $M_7C_3$ and $ ({\gamma}+ M_7C_3)$ eutectic in the alloy No 3. respectively.

• Journal of the Korea Institute of Building Construction
• /
• v.10 no.4
• /
• pp.67-74
• /
• 2010

Currently domestic rural communities are coping with the modernization of farming and agricultural competitiveness. Nevertheless, year after year many agricultural facilities have accidents due to the collapse or damage of facilities due to natural disasters or technical problems. This research is the development of a P-C-M prototype support system to solve the problems related to collapse or damage accidents at agricultural facilities. The P-C-M support system is a process encompassing procurement, construction and maintenance. In this research, a P-C-M support system process module design is performed, a P-C-M support system algorithm is developed, and a P-C-M support prototype system is developed. In conclusion, the developed P-C-M support system is expected to contribute to information-sharing on agricultural facilities, and communication between the user and suppliers.

• Journal of Sericultural and Entomological Science
• /
• v.39 no.2
• /
• pp.106-113
• /
• 1997

Three indigenous mulberry species of Morus tiliaefolia Makino, Morus mongolica C. K. Shneider and Morus bombycis Koidz. were naturally crossed and their fertilities and fruit characteristics were investigated during the years of 1996 and 1997. M. tiliaefolia Makino and M. mongolica C.K. Schneider showed low fertility, but M. bombycis Koidz. was medium in fertility. The fruits of M. tiliaefolia Makino were red-purple and midium in size and high sugar content, but those of M. mongolica C.K. Schneider were light red and small but extremely high sugar content. The total acidity of fruits was 0.73, 0.50 and 0.36-0.94% in M. tiliaefolia Makino, M. mongolica C.K. Schneider and M. bombycis Koidz. respectively. Regarding ripenening stage, M. mongolica C.K. Schneider was early and M. tiliaefolia Makino was medium, while M. bombycis Koidz was early or medium.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.24 no.1
• /
• pp.39-51
• /
• 1991

The primary production of phytoplankton in oyster farming bays were seasonally measured by $^{14}C$ method in Hansan-Koje Bay and Kamagyang Bay for one year period. In Hansan-Koje Bay, mean daily prima production was $0.52gC/m^2/day\;(0.22{\~}1.02gC/m^2/day)$, and it was relatively high in summer and low in winter. Annual primary production was estimated to be $189gC/m^2/yr.$. Mean chlorophyll a content was $1.70mg/m^3$, and it was relatively high in summer. In Kamagyang Bay, mean daily prima production was $0.91gC/m^2/day(0.11{\~}3.61gC/m^2/day)$. and it was maximum in summer and minimum in fall. Annual primary production was estimated to be $334gC/m^2/yr$. Mean chlorophyll a concentration was $2.34mg/m^3$, and it was maximum in summer and relatively high in winter. Considering the water area of the two osyter farming bays, annual carbon production by phytoplankton were 9,450 ton in Hansan-Koje Bay and 37,000 ton in Kamagyang Bay. In general pattern of primary production in these bays, high production occurs in summer with increasing trend since spring.

• Bulletin of the Korean Mathematical Society
• /
• v.26 no.1
• /
• pp.69-74
• /
• 1989

Recently one of the present authors [2] asserted that a real hypersurface of a complex space form M$^{n}$ (c), c.neq.0, is of cyclic parallel if and only if AJ=JA and he showed also a complete and connected cyclic-parallel real hypersurface of M$^{n}$ (c), is congruent to type $A_{1}$, $A_{2}$ or A according as c>0 or c<0. A real hypersurface of a complex space form M$^{n}$ (c) is said to be covariantly cyclic constant if the cyclic sum of covariant derivative of the second fundamental form is constant. The purpose of the present paper is to extend theorem 3 and 4 in [2] when the hypersurfaces are of coveriantly cyclic constant, that is a real hypersurface of a complex space form M$^{n}$ (c), c.neq.0, is of covariantly cyclic constant if an only if AJ=JA, and a complete and connected covariantly cyclic constant real hypersurface of M$^{n}$ (c) is congruent to type $A_{1}$, $A_{2}$ or a according as c>0 or c<0.

• Korean Journal of Optics and Photonics
• /
• v.18 no.5
• /
• pp.333-336
• /
• 2007

A Strained Layer Multiquantum-Well (SL-MQW) distributed feedback laser at a wavelength of 1.31 um operating from $-40^{\circ}C$ to $85^{\circ}C$ without any cooling is grown by metal-organic chemical vapor deposition (MOCVD). Lasers with high slope efficiency are achieved through careful optimization of a SL-MQW active layer, especiallyoptimizing the amount of strain, the well thickness, the barrier thickness, the number of wells, and the active layer width. In this paper, we obtain the slope efficiencies of 0.38[mW/mA] and 0.26 [mW/mA] at $25^{\circ}C$ and $85^{\circ}C$, respectively. Threshold currents are 7.1[mA] and 19.8[mA] at $25^{\circ}C$ and $85^{\circ}C$, respectively.