• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.101-101
• /
• 2010

ZnO shows a direct band gap of 3.37eV, large exciton binding energy (~60 meV), high oxidation ability, high sensitivity to many gases, and low cost, and it has been used in various applications such as transparent electrodes, light emitting diodes (LEDs), gas sensors and photocatalysts. Among these applications ZnO as photocatalyst has considerably attracted attention over the past few years because of its high activities in removing organic contaminants generated from industrial activities. In this research, ZnO nanoparticles were synthesized by spray-pyrolysis method using the zinc acetate dihydrate as starting material at synthesis temperature of $900^{\circ}C$ with concentration varied from 0.01 to 1.0M. The physical and chemical properties of the synthesized ZnO nanoparticles were examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transformation Infrared (FT-IR), and UV-vis spectroscopy. The Miller indices of XRD patterns indicate that the synthesized ZnO nanoparticles showed a hexagonal wurtzite structure. With increased precursor concentration, a primary, secondary particle sizes of ZnO nanoparticles increased by 0.8 to $1.5{\mu}m$ and 15 to 35nm, and their crystallinity was improved. Methyleneblue (MB) solution ($1{\mu}M$) as a test comtaminant was prepared for evaluating the photocatalytic activities of ZnO nanoparticles synthesized in different precursor concentration. The results show that the photocatalytic efficiency of ZnO nanoparticles was gradually enhanced by increased precursor concentration.

• Journal of the Korean Society for Heat Treatment
• /
• v.14 no.3
• /
• pp.160-166
• /
• 2001

The change of ribbon geometry, microstructure and shape recovery with Mn contents, wheel speed and various annealing temperature have been studied in Fe-X%Mn-5Cr-5Co-4Si (X%=15, 20, 24) shape memory alloy (SMA) ribbons rapidly solidfied by single roll chill-block melt-spinning process. The thickness and width of melt-spun ribbons are reduced, results in refining and uniformalizing grains with increasing wheel speed. In the ribbons melt-spun at a wheel speed of 15m/sec, both ${\varepsilon}$ and ${\alpha}^{\prime}$martensites are formed in ribbon 1 (15.5wt%Mn), while only ${\varepsilon}$ martensite is revealed in ribbon 2 (20.2wt%Mn) and ribbon 3 (23.5wt%Mn). The volume fraction of ${\varepsilon}$ martensite is decreased with increasing Mn contents, and those of ${\varepsilon}$ as well ${\alpha}^{\prime}$martensites are increased due to thermal stress relief and grain growth with increasing annealing temperature. Ms temperatures of the ribbons 1, 2 and 3 are fallen with increasing Mn contents. $M_s$ temperatures of the ribbons 1, 2 and 3 annealed at $300^{\circ}C$ for 3 min are risen abruptly, but are nearly constant even at higher annealing temperature, i.e., 400, 500 and $600^{\circ}C$ for 3 min. Shape recovery of the ribbons 1, 2 and 3 increased 30%, 52% and 69% with Mn contents, respectively. Shape recovery of ribbon 1 (15.5wt%Mn) formed ${\varepsilon}$ and ${\alpha}^{\prime}$martensites decreased because of the presence of ${\alpha}^{\prime}$martensite but those of ribbon 2 (20.2wt%Mn) and ribbon 3 (23.5wt%Mn) formed ${\varepsilon}$ martensite increased with increasing annealing temperature.

• Journal of Microbiology and Biotechnology
• /
• v.4 no.2
• /
• pp.102-107
• /
• 1994

The $\beta$-1,4-endoglucanase gene from Actinomyces sp. 40 was cloned into Escherichia coli DH5$\alpha$ with pUC19. Chromosomal DNA from Actinomyces sp. 40 was cleaved with the restriction enzyme Sau3AI and ligated into pUC19 for the transformation of Escherichia coli DH5$\alpha$. Positive clones of $\beta$-1,4-endoglucanase gene were detected as the clear zones on a medium supplemented with carboxymethylcellulose (CMC). This transformant possessed a single plasmid, designated pDS1, which contained the vector DNA and a 3.5 kilobase (kb) Sau3AI insertion fragment encoding endoglucanase. The size of the cloned fragment was reduced to 2.0 kb. The endoglucanase activity produced by the E. coli DH5$\alpha$ (pDS6) was higher than that of Actinomyces sp. 40 strain. The optimum pH and temperature of the cloned enzyme were pH 4.0$\sim$5.0 and 55$^{\circ}C$, respectively. The cloned enzyme was stable at 55$^{\circ}C$ or below and in buffer ranging from pH 4.0 to 7.0. The enzyme degraded CMC but did not degrade xylan, cellobiose, and methyl-umbelliferylcellobiopyranoside (MUC).

• Applied Biological Chemistry
• /
• v.36 no.6
• /
• pp.562-566
• /
• 1993

The conditions required for plant transformation through the electroporation system and for the electrofusion of the prtoplasts were investigated for geranium (Pelargonium zonale hybrids). The optimum condition for electroporation was 1.77 kV/cm for $40\;{\mu}sec$ under which 70% of the protoplasts were viable and 58% of the viable protoplasts were stained with methylene blue. The pBin19 DNA plasmid used as a carrier vector was isolated from E.coli $DH5{\alpha}$ strain, purified, identified by the electrophoresis on agarose gel and electroporated into the protoplasts. The KM8 liquid medium gave better cell division than any other media. One MHz of AC frequency with 40 V/cm of amplitude for 15 sec followed by 0.5 kV/cm of DC amplitude for $60\;{\mu}sec$ was most efficient for the electrofusion of protoplasts.

• Korean Journal of Bronchoesophagology
• /
• v.16 no.1
• /
• pp.39-46
• /
• 2010

Background and Objectives Various tumor markers have been studied in an attempt to evaluate and decide the optimal treatment of the patients with head and neek squamous cell carcinoma (HNSCC). A nuclear antigen Ki-67 is a proliferative marker of tumor cells in all phases of cell cycle except G0. c-met gene, the tyrosine kinase receptor for hepatocyte growth tactor, may play various roles in malignant transformation. The authors evaluated the prognostic significance of Ki-67 and c-Met in surgical specimens of HNSCC to determine the relationship with the various clinicopathological characteristics. Materials and Methods Formatin-fixed paraffin-embedded surgical specimens were obtained from 54 patients with HNSCC. Ki-67 and c-Met expressions were analyzed by immunohistochemical staning and were compared with the clinicopathological characteristics such as, pathologic differentiation, tumor stage, clinical stage and lymph node metastasis. Results Ki-67 and c-Met over-expression was detected in 66.7% and 90.7% in HNSCC. There was positive correlation of increased expression of Ki-67 with tumor stage. and clinical stage, increased expression of e-Met with tumor stage, clinical stage, and nodal status. The expression of c-Met had a significant positive relationship with Ki-67 index (p<0.05). Conclusion Therefore, Ki-67 and c-Met are useful markers of tumor progression, aggressiveness and prognosis in HNSCC.

• BMB Reports
• /
• v.40 no.3
• /
• pp.341-348
• /
• 2007

Herpesvirus saimiri (HVS), a member of the $\delta$-herpesvirus family, encodes an oncoprotein called Saimiri Transforming Protein (STP) which is required for lymphoma induction in non-human primates. Previous study has shown that STP-C, an oncoprotein of HVS, activates NF-$\kappa$B signaling pathway. However, the detailed mechanism of STP-Cmediated NF-$\kappa$B activation has not been reported yet. We first report that STP-C interacts with TRAF6 protein in vivo and in vitro and further investigation shows that $Glu_{12}$ residue of STP-C is critical for binding to TRAF6. Introduction of ubiquitin together with STP-C augments NF-$\kappa$B activity compared to that of STP-C expression alone. STP-C expression further induces ubiquitination of endogenous TRAF6. In addition, either a deubiquitination enzyme, CYLD or a dominant negative E2-conjugation enzyme reduced NF-$\kappa$B activity in spite of the presence of STP-C, supporting that the interaction between STP-C and TRAF6 induces ubiquitination of TRAF6. NF-$\kappa$B activation by STP-C through the ubiquitinated TRAF6 causes the increased production of IL-8, an inflammatory chemokine and the enhanced expression of costimulatory molecule ICAM, which might ultimately contribute cellular transformation by the exposure of HVS-infected cells with inflammatory microenvironment and chronic activation.

• Plant Biotechnology Reports
• /
• v.3 no.2
• /
• pp.157-165
• /
• 2009

Human erythropoietin (EPO) is a leading product in the biopharmaceutical market, but functional EPO has only been produced in mammalian cells, which limits its application and drives up the production costs. Using plants to produce human proteins may be an alternative way to reduce the cost. However, a recent report demonstrated that overexpression of the human EPO gene (EPO) in tobacco or Arabidopsis rendered males sterile and retarded vegetative growth, which raises concern whether EPO might interfere with hormone levels in transgenic plants. In the present study, we demonstrated that overexpressing EPO with additional 5'-His tag and 3' ER-retention peptides in tobacco did not cause any developmental defect compared to GUS plants. With our method, all 20 transgenic plants grew on selective medium and, further confirmed by PCR, were fertile. Most of them grew similarly compared to GUS plants. Only one transgenic plant (EPO2) was shorter in plant height but had twice the life span compared to other transgenic plants. When 11 randomly selected EPO plants, along with the abnormal plant EPO2, were subjected to RT-PCR analysis, all of them had detectable EPO transcripts. However, their protein levels varied considerably; seven of them had detectable EPO proteins analyzed by western blot. Our results indicate that overexpressing human EPO protein in plants does not have detrimental effects on growth and development. Our transformation systems allow us to further explore the possibility of glycoengineering tobacco plants for producing functional EPO and its derivatives.

• Journal of Sensor Science and Technology
• /
• v.22 no.2
• /
• pp.162-173
• /
• 2013

The purpose of this paper is to classify VOC gases by emulating the characteristics found in biological olfaction. For this purpose, we propose new signal processing method based a polymeric chemical sensor array consisting of 4096 sensors which is created by NEUROCHEM project. To remove unstable sensors generated in the manufacturing process of very large scaled chemical sensor array, we used discrete wavelet transformation and cosine similarity. And, to remove the supernumerary redundancy, we proposed the method of selecting candidates of representative sensor representing sensors with similar features by Fuzzy c-means algorithm. In addition, we proposed an improved algorithm for selecting representative sensors among candidates of representative sensors to better enhance classification ability. However, Classification for very large scaled sensor array has a great deal of time in process of learning because many sensors are used for learning though a redundancy is removed. Throughout experimental trials for classification, we confirmed the proposed method have an outstanding classification ability, at transient state as well as steady state.

• Korean Journal of Plant Tissue Culture
• /
• v.24 no.5
• /
• pp.313-317
• /
• 1997

Leaf segments of the potato (Solanum tuberosum L.) genotypes, ND860-2, Norchip, Russet Norkotah, Goldrush, and Norqueen Russet were transformed with the coat protein gene of potato virus Y (PVY). The white-skinned genotypes, ND860-2 and Norchip, were easily transformed and regenerated into shoots, whereas the three russet-skinned genotypes had low frequencies of regeneration. Transformed shoots were generally recovered in four to six weeks. Antibody to PVY coat protein detected a single band of 30 kD in western blots of transgenic plants. Transformed plants had a normal phenotype in the greenhouse and many showed a delayed buildup of PVY following inoculation. Several transgenic lines had negative ELISA readings 85 days after inoculation. Transgenic lines which did not show detectable levels of PVY antigen will be further tested for resistance to PVY.

• Restorative Dentistry and Endodontics
• /
• v.45 no.3
• /
• pp.32.1-32.12
• /
• 2020

Objectives: To evaluate the polymerization efficiency of a matrix-modified bulk-fill composite, and compare it to a conventional composite which has a similar filler system. The degree of conversion (DC%) and monomer elution were measured over different storage periods. Additionally, fillers' content was examined. Materials and Methods: Cylindrical specimens were prepared, in bulk and incrementally, from Filtek Bulk Fill (B) and Filtek Supreme XTE (S) composites using a Teflon mold, for each test (n = 6). Using attenuated total reflection method of Fourier transformation infrared spectroscopy, DC% was measured after 24 hours, 7 days, and 30 days. Using high-performance liquid chromatography, elution of hydroxyethyl methacrylate, triethylene glycol dimethacrylate, urethane dimethacrylate, and bisphenol-A glycidyl dimethacrylate was measured after 24 hours, 7 days and 30 days. Filler content was examined by scanning electron microscopy (SEM). Data were analyzed using 2-way mixed-model analysis of variance (α = 0.05). Results: There was no significant difference in DC% over different storage periods between B-bulk and S-incremental. Higher monomer elution was detected significantly from S than B. The elution quantity and rate varied significantly over storage periods and between different monomers. SEM images showed differences in fillers' sizes and agglomeration between both materials. Conclusions: Matrix-modified bulk-fill composites could be packed and cured in bulk with polymerization efficiency similar to conventional composites.