• Korean Journal of Environmental Biology
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• v.36 no.3
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• pp.314-318
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• 2018

A marine algal species was collected from Sacheonjin, Gangneung located on the eastern coast of Korea during a survey of marine algal flora. This alga shares the generic features of Membranoptera belonging to the subfamily Delesserioideae and is characterized by the presence of combined features of membranous, monostromatic thalli attached by a solid discoid holdfast, blades with a conspicuous terete stipe-like midrib and microscopic lateral veins, entire margins, irregularly alternate to dichotomous branching, and obtuse apices growing apically. In a phylogenetic tree based on rbcL sequences, the Korean alga nests in the same clade with M. alata from the eastern North Atlantic. The genetic distance between both the sequences within the clade was calculated as 0.0%. Based on the morphological and molecular analyses, this Korean species is identified as the generic type, M. alata. This is the first record in the list of Korean marine algal flora.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.280-280
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• 2013

Using both experimentaland theoretical methods, we have investigated the structural and electronic properties of self-assembled two-dimensional organic molecule (hexaaza-triphenylene-hexacarbonitrile, HATCN), which is used as an efficient OLED hole injection material, on Au(111) surfaces. Low-temperature scanning tunneling microscope (STM) measurements revealed that self-assembled linear and hexagonal porous structures are formed at atomic steps and terraces of Au(111), respectively. We also found that the hexagonal porous structure have chirality and forms only small (＜1,000 nm2) phase-separated chiral domains that can easily change their chiral phase in subsequence STM images at 80 K. To explain these observations, we calculated the molecular-molecular and molecule-surface interaction energies by using first-principles density functional theory method. We found that the change of their chiral phase resulted from the competition between the two energies. These results have not only verified our experimental observations, but also revealed the delicate balance between different interactions that caused the self-assembed structures at the surface.

• ALGAE
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• v.31 no.3
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• pp.219-230
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• 2016

The Euglena deses group are common freshwater species composed of E. adhaerens, E. carterae, E. deses, E. mutabilis, and E. satelles. These species are characterized by elongated cylindrical worm-like cell bodies and numerous discoid chloroplasts with a naked pyrenoid. To understand the cryptic diversity, species delimitation and phylogenetic relationships among members of the group, we analyzed morphological data (light and scanning electron microscopy) and molecular data (nuclear small subunit [SSU] and large subunit [LSU] rDNAs and plastid SSU and LSU rDNAs). Bayesian and maximum likelihood analyses based on the combined four-gene dataset resulted in a tree consisting of two major clades within the group. The first clade was composed of two subclades: the E. mutabilis subclade, and the E. satelles, E. carterae, and E. adhaerens subclade. The E. mutabilis subclade was characterized by a lateral canal opening at the anterior end and a single pellicular stria, whereas the E. satelles, E. carterae, and E. adhaerens subclade was characterized by an apical canal opening at the anterior end of the cell and double pellicular striae. The second clade consisted of 20 strains of E. deses, characterizing by a subapical canal opening at the anterior end and double pellicular striae, but they showed cell size variation and high genetic diversity. Species boundaries were tested using a Bayesian multi-locus species delimitation method, resulting in the recognition of five cryptic species within E. deses clade.

• Journal of Yeungnam Medical Science
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• v.24 no.2
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• pp.329-332
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• 2007

Solar retinopathy is a rare but well-recognized clinical entity of macular damage, caused by viewing a solar eclipse or direct sun gazing. A 21-year-old man gazed at the sun for approximately thirty seconds at noon using a monocular telescope with his left eye. Forty-eight hours after sun gazing, the patient experienced symptoms of blurred vision and central scotoma in the left eye. Eight months after sun gazing, the visual acuity decreased from 1.0 to 0.1 in the left eye and the fundus examination showed a round, yellowish-white discoid lesion at the left fovea. Fluorescein angiography showed an early window defect in the fovea of the left eye, that persisted without size change during the late phase resulting from atrophy of the retinal pigment epithelium. A small, central scotoma of the left eye was also found in the visual field test. The visual acuity was unchanged at the end of a one-year follow-up period.

• Animal cells and systems
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• v.16 no.6
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• pp.479-487
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• 2012

Biological attachment device is optimized in insect legs for attachment onto the variety of natural substrate. We have studied the microstructural characteristics of the tarsal appendages in the ladybug Harmonia axyridis using scanning electron microscopy to reveal the attachment system of their legs. The attachment devices are composed of claws and adhesive pads. The claws are connected with pretarsal segment, and their apical diverged hooks are developed to hold rough substrates. In contrast, the adhesive pads have an adhesive function onto smooth surface. The pads are interspersed at the ventral part of each tarsomere, and are composed of two kinds of hairy setae. The discoid tip seta (DtS) has a spoon-shaped endplate usually with a rounded concave structure, whereas the pointed tip seta (PtS) has a pointed tip, usually with a hooked endplate. While the PtS is broadly localized concentrically on the marginal area of both the proximal and distal pads, the DtS can be seen at the central areas of each adhesive pad except for the hind legs. Our findings demonstrate the presence of the direction-dependence pattern of the fibrillar system as well as a functional modification of the tenent setae to achieve proper contact with almost any kind of substrates.

• Korean Journal of Veterinary Research
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• v.46 no.3
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• pp.275-278
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• 2006

A 7-month-old brown pig with a discoid and pedunculate mass measuring $14.0{\times}12.5{\times}2.5cm$ on the skin of the right shoulder was noted at the slaughter house in Jeju. The surface of mass approximately $7{\times}4cm$ was interfaced with skin. The color of mass with firm consistency was mainly black and partially white on cut surface. Histopathologically, numerous unencapsulated endocrine-like cellular nodules of epithelioid cell type with abundant intracytoplasmic black pigment, melanin, were occupied in dermis and subcutis. Most of nodules in deep dermis were surrounded by lightly pigmented spindle cells and loose fibrous tissues. Mitotic figures were infrequently observed. The overlying epidermis was hyperplastic due to the down-growth of rete peg. Based on the gross and histopathologic findings, this case was diagnosed as cutaneous melanoma. In our best knowledge, this is the first case of swine cutaneous melanoma in Korea.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.379-379
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• 2010

Recent technical advances in OLEDs (organic light emitting devices) requires more and more the improvement in low operation voltage, long lifetime, and high luminance efficiency. Inverted top emission OLEDs (ITOLED) appeared to overcome these problems. This evolved to operate better luminance efficiency from conventional OLEDs. First, it has large open area so to be brighter than conventional OLEDs. Also easy integration is possible with Si-based driving circuits for active matrix OLED. But, a proper buffer layer for carrier injection is needed in order to get a good performance. The buffer layer protects underlying organic materials against destructive particles during the electrode deposition and improves their charge transport efficiency by reducing the charge injection barrier. Hexaazatriphenylene-hexacarbonitrile (HAT-CN), a discoid organic molecule, has been used successfully in tandem OLEDs due to its high workfunction more than 6.1 eV. And it has the lowest unoccupied molecular orbital (LUMO) level near to Fermi level. So it plays like a strong electron acceptor. In this experiment, we measured energy level alignment and hole current density on inverted OLED structures for hole injection. The normal film structure of Al/NPB/ITO showed bad characteristics while the HAT-CN insertion between Al and NPB greatly improved hole current density. The behavior can be explained by charge generation at the HAT-CN/NPB interface and gap state formation at Al/HAT-CN interface, respectively. This result indicates that a proper organic buffer layer can be successfully utilized to enhance hole injection efficiency even with low work function Al anode.

• Mycobiology
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• v.47 no.3
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• pp.319-328
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• 2019

Cytospora is a genus including important phytopathogens causing severe dieback and canker diseases distributed worldwide with a wide host range. However, identification of Cytospora species is difficult since the currently available DNA sequence data are insufficient. Aside the limited availability of ex-type sequence data, most of the genetic work is only based on the ITS region DNA marker which lacks the resolution to delineate to the species level in Cytospora. In this study, three fresh strains were isolated from the symptomatic branches of Elaeagnus angustifolia in Xinjiang Uygur Autonomous Region, China. Morphological observation and multi-locus phylogenetic analyses (ITS, LSU, ACT and RPB2) support these specimens are best accommodated as a distinct novel species of Cytospora. Cytospora elaeagnicola sp. nov. is introduced, having discoid, nearly flat, pycnidial conidiomata with hyaline, allantoid conidia, and differs from its relatives genetically and by host association.

• Korean Journal of Environmental Biology
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• v.36 no.3
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• pp.308-313
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• 2018

During a survey of marine algal flora, a red algal species was collected from Giseong, Uljin located on the eastern coast of Korea. This species has the generic features of Cryptonemia belonging to Halymeniaceae, and is characterized by the presence of erect foliose thalli arising from a discoid holdfast, somewhat fan-shaped blade with an evanescent midrib at the base, narrow main axes with blade-like wings of slightly undulate margin, a perennial stalk, and entwined filamentous medulla with refractive stellate cells. In a phylogenetic tree based on rbcL sequence, the Korean alga nests in the same clade with C. lomation from France and C. seminervis from Spain. Genetic divergence among the sequences within the clade was not recognized thus suggesting that both the species are conspecific. The name C. lomation considered to be valid nomenclaturally is accepted for the entity. Based on the morphological and molecular analyses, the Korean alga is identified as C. lomation, originally described from Italy. This confirms the occurrence of C. lomation in Korea. The species appears to be distributed in the temperate region influenced more or less by the North Korea Cold Current.

• Restorative Dentistry and Endodontics
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• v.39 no.2
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• pp.109-114
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• 2014

Objectives: Recurrent caries was partly ascribed to lack of antibacterial properties in composite resin. Silver and zinc nanoparticles are considered to be broad-spectrum antibacterial agents. The aim of the present study was to evaluate the antibacterial properties of composite resins containing 1% silver and zinc-oxide nanoparticles on Streptococcus mutans and Lactobacillus. Materials and Methods: Ninety discoid tablets containing 0%, 1% nano-silver and 1% nano zinc-oxide particles were prepared from flowable composite resin (n = 30). The antibacterial properties of composite resin discs were evaluated by direct contact test. Diluted solutions of Streptococcus mutans (PTCC 1683) and Lactobacillus (PTCC 1643) were prepared. 0.01 mL of each bacterial species was separately placed on the discs. The discs were transferred to liquid culture media and were incubated at $37^{\circ}C$ for 8 hr. 0.01 mL of each solution was cultured on blood agar and the colonies were counted. Data was analyzed with Kruskall-Wallis and Mann-Whitney U tests. Results: Composites containing nano zinc-oxide particles or silver nanoparticles exhibited higher antibacterial activity against Streptococcus mutans and Lactobacillus compared to the control group (p < 0.05). The effect of zinc-oxide on Streptococcus mutans was significantly higher than that of silver (p < 0.05). There were no significant differences in the antibacterial activity against Lactobacillus between composites containing silver nanoparticles and those containing zinc-oxide nanoparticles. Conclusions: Composite resins containing silver or zinc-oxide nanoparticles exhibited antibacterial activity against Streptococcus mutans and Lactobacillus.