• Korean Journal of Plant Taxonomy
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• v.48 no.4
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• pp.260-277
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• 2018

The evolution of chromosome numbers and the karyotype structure is a prominent feature of plant genomes contributing to or at least accompanying plant diversification and eventually leading to speciation. Polyploidy, the multiplication of whole chromosome sets, is widespread and ploidy-level variation is frequent at all taxonomic levels, including species and populations, in angiosperms. Analyses of chromosome numbers and ploidy levels of 252 taxa of Korean non-commelinid monocots indicated that diploids (ca. 44%) and tetraploids (ca. 14%) prevail, with fewer triploids (ca. 6%), pentaploids (ca. 2%), and hexaploids (ca. 4%) being found. The range of genome sizes of the analyzed taxa (0.3-44.5 pg/1C) falls well within that reported in the Plant DNA C-values database (0.061-152.33 pg/1C). Analyses of karyotype features in angiosperm often involve, in addition to chromosome numbers and genome sizes, mapping of selected repetitive DNAs in chromosomes. All of these data when interpreted in a phylogenetic context allow for the addressing of evolutionary questions concerning the large-scale evolution of the genomes as well as the evolution of individual repeat types, especially ribosomal DNAs (5S and 35S rDNAs), and other tandem and dispersed repeats that can be identified in any plant genome at a relatively low cost using next-generation sequencing technologies. The present work investigates chromosome numbers (n or 2n), base chromosome numbers (x), ploidy levels, rDNA loci numbers, and genome size data to gain insight into the incidence, evolution and significance of polyploidy in Korean monocots.

• Journal of Microbiology and Biotechnology
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• v.29 no.8
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• pp.1193-1203
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• 2019

We investigated the protective effects of 3-bromo-4,5-dihydroxybenzaldehyde (BDB) from Polysiphonia morrowii Harvey against hydrogen peroxide ($H_2O_2$)-induced apoptosis in Vero cells. BDB exhibited scavenging activity for DPPH, hydroxyl, and alkyl radicals. BDB also inhibited $H_2O_2$-induced lipid peroxidation, cell death, and apoptosis in Vero cells by inhibiting the production of ROS. To evaluate the molecular mechanisms of apoptosis inhibition, the expression of Bax/Bcl-xL and $NF-{\kappa}B$ was assessed by western blot assay. BDB significantly suppressed the cleavage of caspase-9 and PARP and reduced Bax levels in $H_2O_2$-induced Vero cells. Besides, BDB suppressed the phosphorylation of $NF-{\kappa}$B and the translocation of p65 in $H_2O_2$-induced cells. Furthermore, we evaluated the effect of BDB on ROS production, cell death, and lipid peroxidation in an $H_2O_2$-stimulated zebrafish embryo model. Taken together, these results indicated that ROS generation and cell death were significantly inhibited by BDB in zebrafish embryos, thereby proving that BDB exerts excellent antioxidant activity in vitro and in vivo.

• The Research Journal of the Costume Culture
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• v.27 no.5
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• pp.461-478
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• 2019

As the concept of "marriage age" gradually disappears, the consumption class of the wedding market includes not only X and Y generations but also Z generations, and each generation has its own characteristics as it is already known, and there are differences in the consumption. So this research analyzed age-related behavior differences in both awareness of and preparation for marriage. Three hundred sixteen unmarried Korean males and females comprised the study population and data was collected from March 5, 2019, to April 3, 2019. The SPSS Statistics 23.0 Package was used for analysis, specifically the functions of frequency, cross tabulation, factor analysis, chi-squared test, Cronbach's alpha, Duncans's new multiple range test (MRT), and analysis of variance (ANOVA). Marriage motivation was analyzed by three factors, and there were significant differences in two types. Marital involvement was analyzed by two factors, and both factors showed significant age-related differences. Concerns relating to marriage preparation were analyzed by four factors, and two varied according to respondent age. Regarding marriage preparation behaviors, the analysis revealed that the marriage preparation method appreciably differed between age groups. Our analysis also found significant age-related differences in "the main media usually used to acquire information" and "the paths preferred for acquiring information in preparing for marriage". We expect that study results will be useful for identifying new research directions, understanding the dimensions of the wedding industry, and developing related marketing strategies.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.4
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• pp.143-148
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• 2019

We have successfully fabricated high aspect-ratio GaN-based nanowires on Si substrates using molecular beam epitaxy (MBE) system for high-efficiency hydrogen generation of photoelectrochemical water splitting. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) demonstrated that p-GaN:Mg and p-InGaN nanowires were grown vertically on the substrate with high density. Furthermore, it was also confirmed that the emission wavelength of p-InGaN nanowire can be adjusted from 552 nm to 590 nm. Such high-aspect ratio p-InGaN nanowire structure will be a solid foundation for the realization of ultrahigh-efficiency photoelectrochemical water splitting through sunlight.

• Journal of Powder Materials
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• v.28 no.2
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• pp.103-109
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• 2021

High-entropy alloys have excellent mechanical properties under extreme environments, rendering them promising candidates for next-generation structural materials. It is desirable to develop non-equiatomic high-entropy alloys that do not require many expensive or heavy elements, contrary to the requirements of typical high-entropy alloys. In this study, a non-equiatomic high-entropy alloy powder Fe_49.5Mn₃₀Co₁₀Cr₁₀C_0.5 (at.%) is prepared by high energy ball milling and fabricated by spark plasma sintering. By combining different ball milling times and ball-to-powder ratios, we attempt to find a proper mechanical alloying condition to achieve improved mechanical properties. The milled powder and sintered specimens are examined using X-ray diffraction to investigate the progress of mechanical alloying and microstructural changes. A miniature tensile specimen after sintering is used to investigate the mechanical properties. Furthermore, quantitative analysis of the microstructure is performed using electron backscatter diffraction.

• Journal of Korean Neurosurgical Society
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• v.64 no.1
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• pp.13-22
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• 2021

Objective : High precision and accuracy are expected in gamma knife radiosurgery treatment. Because of the requirement of clinically applying complex radiation and dose gradients together with a rapid radiation decline, a dedicated quality assurance program is required to maintain the radiation dosimetry and geometric accuracy and to reduce all associated risk factors. This study investigates the validity of Leksell Gamma plan (LGP)10.1.1 system of 5th generation Gamma Knife Perfexion as modified variable ellipsoid modeling technique (VEMT) method. Methods : To verify LGP10.1.1 system, we compare the treatment plan program system of the Gamma Knife Perfexion, that is, the LGP, with the calculated value of the proposed modified VEMT program. To verify a modified VEMT method, we compare the distributions of the dose of Gamma Knife Perfexion measured by Gafchromic EBT3 and EBT-XD films. For verification, the center of an 80 mm radius solid water phantom is placed in the center of all sectors positioned at 16 mm, 4 mm and 8 mm; that is, the dose distribution is similar to the method used in the x, y, and z directions by the VEMT. The dose distribution in the axial direction is compared and analyzed based on Full-Width-of-Half-Maximum (FWHM) evaluation. Results : The dose profile distribution was evaluated by FWHM, and it showed an average difference of 0.104 mm for the LGP value and 0.130 mm for the EBT-XD film. Conclusion : The modified VEMT yielded consistent results in the two processes. The use of the modified VEMT as a verification tool can enable the system to stably test and operate the Gamma Knife Perfexion treatment planning system.

• Korean Journal of Metals and Materials
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• v.56 no.12
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• pp.910-914
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• 2018

Since catalyst technology is one of the promising technologies to improve the working performance of next generation energy and electronic devices, many efforts have been made to develop various catalysts with high efficiency at a low cost. However, there are remaining challenges to be resolved in order to use the suggested catalytic materials, such as platinum (Pt), gold (Au), and palladium (Pd), due to their poor cost-effectiveness for device applications. In this study, to overcome these challenges, we suggest a useful method to increase the surface area of a noble metal catalyst material, resulting in a reduction of the total amount of catalyst usage. By employing block copolymer (BCP) self-assembly and nano-transfer printing (n-TP) processes, we successfully fabricated sub-20 nm Pt line and cross-bar patterns. Furthermore, we obtained a highly ordered Pt cross-bar pattern on a Ni thin film and a Pt-embedded Ni thin film, which can be used as hetero hybrid alloy catalyst structure. For a detailed analysis of the hybrid catalytic material, we used scanning electron microscope (SEM), transmission electron microscope (TEM) and energy-dispersive X-ray spectroscopy (EDS), which revealed a well-defined nanoporous Pt nanostructure on the Ni thin film. Based on these results, we expect that the successful hybridization of various catalytic nanostructures can be extended to other material systems and devices in the near future.

• Korean Journal of Metals and Materials
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• v.49 no.1
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• pp.25-31
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• 2011

Solid oxide fuel cells (SOFCs) have many attractive features for widespread applications in generation systems. Recently, stainless steels have attractive materials for metallic bipolar plate because metallic bipolar plates have many benefits compared to others such as graphite and composite bipolar plates. SOFC operates on high temperature of about $800{\sim}1000^{\circ}C$ than other fuel cell systems. Thus, many studies have attempted to reduced the operation temperature of SOFC to about $600{\sim}800^{\circ}C$, which is the intermediate temperature (IT) of SOFC. Low cost and high-temperature corrosion resistance are very important for the practical applications of SOFC in various industries. In this study, two specimens, 304 and 430 stainless steels with and without different pre-surface treatments on the surface were investigated. And, specimens were exposed at high temperature in the box furnace under oxidation atmosphere of $800^{\circ}C$. Oxidation behavior have been investigated with the materials exposed at different times (100 hrs and 400 hrs) by SEM, EDS and XRD. By increasing exposure time, the amount of metal oxide increased in the order like; STS304 < STS430 and As-received < As-polished < Sand-blast specimens.

• Microbiology and Biotechnology Letters
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• v.49 no.2
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• pp.138-147
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• 2021

The overproduction of reactive nitrogen species (RNS) and reactive oxygen species (ROS) causes oxidative damage to neuronal cells, leading to the progression of neurodegenerative diseases. In this study, we determined the nitric oxide radical (NO), hydroxyl radical (·OH), and superoxide anion radical (O₂^-) scavenging activities of apigenin. Our results showed that apigenin exhibited remarkable, concentration-dependent ·OH, O₂^-, and NO radical scavenging activities. Particularly, apigenin indicated the strongest ·OH radical scavenging activity with 93.38% in the concentration of 100 µM. Furthermore, we also investigated the protective effects of apigenin against hydrogen peroxide (H₂O₂)-induced oxidative stress in SH-SY5Y cells. The H₂O₂ treatment resulted in a significant decrease in cell viability, as well as an increase in lactate dehydrogenase (LDH) release and ROS production compared with the H₂O₂-nontreated SH-SY5Y cells. However, the cell viability significantly increased in the apigenin-treated group, as well as inhibited ROS generation and LDH release compared with the H₂O₂-induced control group. To elucidate the protective mechanisms of apigenin against oxidative stress in SH-SY5Y, we analyzed the apoptosis-related protein expression. The apigenin treatment resulted in the downregulated expression of apoptosis-related protein markers, such as cytochrome C, cleaved caspase-3, poly (ADP)-ribose polymerase (PARP), and B-cell lymphoma 2-associated X (Bax), as well as the upregulated expression of anti-apoptosis markers such as B-cell lymphoma 2 (Bcl-2). In this study, we report that apigenin exhibits a neuroprotective effect against oxidative stress in SH-SY5Y cells. These results suggest that apigenin may be considered as a potential agent for neurodegenerative disease prevention.

• International Journal of Oral Biology
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• v.46 no.1
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• pp.15-22
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• 2021

Alpha-lipoic acid (ALA) is a naturally occurring antioxidant and has been previously used to treat diabetes and cardiovascular disease. However, the autophagy effects of ALA against oxidative stress-induced dopaminergic neuronal cell injury remain unclear. The aim of this study was to investigate the role of ALA in autophagy and apoptosis against oxidative stress in the SH-SY5Y human dopaminergic neuronal cell line. We examined SH-SY5Y phenotypes using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay (cell viability/proliferation), 4′,6-diamidino-2-phenylindole dihydrochloride nuclear staining, Live/Dead cell assay, cellular reactive oxygen species (ROS) assay, immunoblotting, and immunocytochemistry. Our data showed ALA attenuated hydrogen peroxide (H2O2)-induced ROS generation and cell death. ALA effectively suppressed Bax up-regulation and Bcl-2 and Bcl-xL down-regulation. Furthermore, ALA increased the expression of the antioxidant enzyme, heme oxygenase-1. Moreover, the expression of Beclin-1 and LC-3 autophagy biomarkers was decreased by ALA in our cell model. Combined, these data suggest ALA protects human dopaminergic neuronal cells against H2O2-induced cell injury by inhibiting autophagy and apoptosis.