• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4205-4209
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• 2011

The $Li_2Mn_{0.5}Fe_{0.5}SiO_4$ silicate was prepared by blending of $Li_2MnSiO_4$ and $Li_2FeSiO_4$ precursors with same molar ratio. The one of the silicates of $Li_2FeSiO_4$ is known as high capacitive up to ~330 mAh/g due to 2 mole electron exchange, and the other of $Li_2FeSiO_4$ has identical structure with $Li_2MnSiO_4$ and shows stable cycle with less capacity of ~170 mAh/g. The major drawback of silicate family is low electronic conductivity (3 orders of magnitude lower than $LiFePO_4$). To overcome this disadvantage, carbon composite of the silicate compound was prepared by sucrose mixing with silicate precursors and heat-treated in reducing atmosphere. The crystal structure and physical morphology of $Li_2Mn_{0.5}Fe_{0.5}SiO_4$ was investigated by X-ray diffraction, scanning electron microscopy, and high resolution transmission electron microscopy. The $Li_2Mn_{0.5}Fe_{0.5}SiO_4$/C nanocomposite has a maximum discharge capacity of 200 mAh/g, and 63% of its discharge capacity is retained after the tenth cycles. We have realized that more than 1 mole of electrons are exchanged in $Li_2Mn_{0.5}Fe_{0.5}SiO_4$. We have observed that $Li_2Mn_{0.5}Fe_{0.5}SiO_4$ is unstable structure upon first delithiation with structural collapse. High temperature cell performance result shows high capacity of discharge capacity (244 mAh/g) but it had poor capacity retention (50%) due to the accelerated structural degradation and related reaction.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.1
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• pp.11-18
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• 2020

High-pressure synchrotron X-ray powder diffraction experiments were performed on natural illite (K_0.65Al₂(Al_0.65Si_3.35)O₁₀(OH)₂) using diamond anvil cell (DAC) under two different pressure transmitting media (PTM), i.e., water and ME41 (methanol:ethanol = 4:1 by volume). When using water as PTM, occasional heating was applied up to about 250℃ while reaching pressure up to 2.7 GPa in order to promote both hydrostatic conditions and intercalation of water molecules into the layer. When using ME41, pressure was reached up to 6.9 GPa at room temperature. Under these conditions, illite did not show any expansion of interlayer distance or phase transitions. Pressure-volume data were used to derive bulk moduli (K₀) of 45(3) GPa under water and 51(3) GPa under ME41 PTM. indicating no difference in compressibility within the analytical error. Linear compressibilities were then calculated to be β^a = 0.0025, β^b = 0.0029, β^c = 0.0144 under ME41 PTM showing the c-axis is ca. six times more compressible than a- and b-axes. These elastic behaviors of illite were compared to muscovite, one of its structural analogues.

• Development and Reproduction
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• v.2 no.1
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• pp.101-109
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• 1998

Spermatogenesis and reproductive cycle of the razor clam, solen grandis, were investigated monthly by histological and cytological observations. Samples were collected from natural intertidal population at Oshik-do, Kunsan, Korea, for one year, beginning from January to December, 1993. solen grandis is dioecious. Morphological structures of the spermatozoon of this species ar esimilar to those of other bivalve spermatozoa having a primitive type; i.e., a small head, a cap-shaped acrosome and a short mid-piece with four mitochondria surrounding axial filament. The head of spermatozoon is approximately 2 \mu m in length and sperm tail is about 20 \mu m long. The axoneme of tail flagellum consists of nine pairs of peripheral microtubules at the periphery and a pair of central microtubules at the center. Four spherical mitochondria form the paranucleus. Spawning occures once a year between early June and July, and the main spawning was observed in July when seawater temperature reaches above 20 \circ C. The reproductive cycle of male razor clam can be divieded into fivesuccessive stages; early active (December to january), late active (January to march), mature (March to early August), partially spawned (June to July), and spent/inactive stage (August to December).

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.36-36
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• 2017

Out of twenty common protein amino acids, there are many kinds of non protein amino acids (NPAAs) that exist as secondary metabolites and exert ecological functions in plants. Mimosine (Mim), one of those NPAAs derived from L. leucocephala acts as an iron chelator and reversely block mammalian cell cycle at G1/S phases. Cysteine (Cys) is decisive for protein and glutathione that acts as an indispensable sulfur grantor for methionine and many other sulfur-containing secondary products. Cys biosynthesis includes consecutive two steps using two enzymes-serine acetyl transferase (SAT) and O-acetylserine (thiol)lyase (OASTL) and appeared in plant cytosol, chloroplast, and mitochondria. In the first step, the acetylation of the ${\beta}$-hydroxyl of L-serine by acetyl-CoA in the existence of SAT and finally, OASTL triggers ${\alpha}$, ${\beta}$-elimination of acetate from OAS and bind $H_2S$ to catalyze the synthesis of Cys. Mimosine synthase, one of the isozymes of the OASTLs, is able to synthesize Mim with 3-hydroxy-4-pyridone (3H4P) instead of $H_2S$ for Cys in the last step. Thus, the aim of this study was to clone and characterize the cytosolic (Cy) OASTL gene from L. leucocephala, express the recombinant OASTL in Escherichia coli, purify it, do enzyme kinetic analysis, perform docking dynamics simulation analysis between the receptor and the ligands and compare its performance between Cys and Mim synthesis. Cy-OASTL was obtained through both directional degenerate primers corresponding to conserved amino acid region among plant Cys synthase family and the purified protein was 34.3KDa. After cleaving the GST-tag, Cy-OASTL was observed to form mimosine with 3H4P and OAS. The optimum Cys and Mim reaction pH and temperature were 7.5 and $40^{\circ}C$, and 8.0 and $35^{\circ}C$ respectively. Michaelis constant (Km) values of OAS from Cys were higher than the OAS from Mim. Inter fragment interaction energy (IFIE) of substrate OAS-Cy-OASTL complex model showed that Lys, Thr81, Thr77 and Gln150 demonstrated higher attraction force for Cys but 3H4P-mimosine synthase-OAS intermediate complex showed that Gly230, Tyr227, Ala231, Gly228 and Gly232 might provide higher attraction energy for the Mim. It may be concluded that Cy-OASTL demonstrates a dual role in biosynthesis both Cys and Mim and extending the knowledge on the biochemical regulatory mechanism of mimosine and cysteine.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.291-298
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• 2020

ZITO/Ag/ZITO multilayer transparent electrodes at room temperature on glass substrates were prepared using RF/DC magnetron sputtering. Transparent conductive films with a sheet resistance of 9.4 Ω/㎡ and a transmittance of 83.2% at 550 nm were obtained for the multilayer structure comprising ZITO/Ag/ZITO (100/8/42 nm). The sheet resistance and transmittance of ZITO/Ag/ZITO multilayer films meant that they would be highly applicable for use in polymer-dispersed liquid crystal (PDLC)-based smart windows due to the ability to effectively block infrared rays (heat rays) and thereby act as an energy-saving smart glass. Effects of the thickness of the PDLC layer and the intensity of ultraviolet light (UV) on electro-optical properties, photopolymerization kinetics, and morphologies of difunctional urethane acrylate-based PDLC systems were investigated using new transparent conducting electrodes. A PDLC cell photo-cured using UV at an intensity of 2.0 mW/c㎡ with a 15 ㎛-thick PDLC layer showed outstanding off-state opacity, good on-state transmittance, and favorable driving voltage. Also, the PDLC-based smart window optimized in this study formed liquid crystal droplets with a favorable microstructure, having an average size range of 2~5 ㎛ for scattering light efficiently, which could contribute to its superior final performance.

• Ecology and Resilient Infrastructure
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• v.7 no.1
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• pp.72-81
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• 2020

Blooms of the small centric diatom Stephanodiscus is quite occasional in winter season in temperate freshwater ecosystems. Often, it leads to degradation of water quality and affects quality of supplied drinking water. In previous studies, naphthoquinone (NQ) compounds have been shown to be effective and selective for controlling winter bloom species Stephanodiscus hantzschii. We conducted a 5 ton scale mesocosm experiment to investigate the effects of NQ on native Stephanodiscus sp. collected from Nakdonggang River in water. After treatment with NQ 4-6 compound (0.2 μM), the cell density of Stephanodiscus sp. was rapidly reduced from 5 × 10³ cells mL^-1 to 0.2 × 10³ cells mL^-1 for 10 days. Additionally, NQ 4-6 compound did not affect physicochemical factors (water temperature, dissolved oxygen, pH, conductivity, nutrients) and biological factors (bacteria, heterotrophic nanoflagellates, zooplankton). Therefore, these findings suggest that the NQ 4-6 compound has potential as an alternative algicidal substances to effectively mitigate natural Stephanodiscus sp. blooms, and the application of NQ 4-6 compound will restore the healthy aquatic ecosystems.

• Food Science of Animal Resources
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• v.31 no.5
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• pp.701-709
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• 2011

This study was performed to establish an effective extraction method of pig placenta extract that could be used for a putative functional food supplement with immunomodulatory effects. In the present study, we used different temperatures (4, 37, 60, 80, and $100^{\circ}C$) and different solvents (chloroform, NaOH, and phosphate buffered saline [PBS]) to extract the pig placenta. Among the different placenta extracts yielded by the different extraction methods, placenta extract (PE) in PBS at $80^{\circ}C$ for 30 min (referred to as PE-PBS80) showed a significant increase of nitric oxide production of up to 22.97 ${\mu}M/10^5$ cells at a 1 mg/mL dose (p<0.05 ) in J774A.1 cells than other extracts and control tested. Using PE-PBS80, further animal challenges were performed to identify the immune-enhanced effects. As a result, orally administered PE-PBS80 showed a significant increase in blood T and B cell activities and immunoglobulin (IgG and IgM) production. IgG and IgM levels increased to 41.53 mg/mL at a 20 mg dose on day 7 and to 27.38 mg/mL at a 10 mg dose on day 14, respectively (p<0.05). Furthermore, PE-PBS80 was also able to significantly enhance the immune modulator cytokine levels (p<0.05) compared to the control and vehicle treatments. Among the evaluated cytokines, the tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) level increased to 28.89 pg/mL at extract doses of 20 and 50 mg, the interleukin-$1{\beta}$ (IL-$1{\beta}$) level increased to 21.52 pg/mL at extract doses of 10, 20, 50 and 75 mg and the interferon (IFN)-${\gamma}$ level increased to 18.24 pg/mL at extract doses of 10, 20, and 50 mg. Therefore, this study presents an effective method for extracting pig placenta extracts and also demonstrates that pig placenta extracts had significant immunomodulatory effects not only at the cellular level but also in a mouse model, suggesting that this material could be used as an excellent candidate functional food supplement.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.1
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• pp.21-26
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• 2011

Ni-YSZ (Yttria Stabilized Zirconia) composite powders were fabricated by glycine nitrate process. The prepared powders were sintered at $1300{\sim}1400^{\circ}C$ for 4 h in air and reduced at $1000^{\circ}C$ for 2 h in a nitrogen and hydrogen atmosphere. The microstructure, electrical conductivity, thermal expansion and mechanical properties of the Ni-YSZ cermets have been investigated with respect to the volume contents of Ni. A porous microstructure consisting of homogeneously distributed Ni and YSZ phases together with well-connected grains was observed. It was found that the open porosity, electrical conductivity, thermal expansion and bending strength of the cermets are sensitive to the volume content of Ni. The Ni-YSZ cermet containing 40 vol% Ni was ascertained to be the optimum composition. This composition offers sufficient open porosity of more than 30 %, superior electrical conductivities of 917.4 S/cm at $1000^{\circ}C$ and a moderate average thermal expansion coefficient of $12.6{\times}10^{-6}^{\circ}C^{-1}$ between room temperature and $1000^{\circ}C$.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.3
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• pp.361-368
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• 2012

Effect of vitamin C (VC) on biochemical, hematological and cortisol profile of growing Holstein calves during summer was investigated. Eighteen calves between 14 and 16 weeks of age were divided equally into two groups. One group received a diet supplemented with VC (20 g/d) for 60 days, while other non-supplemented diet fed group served as a control (CON). The temperature humidity index (THI) was recorded and computed during the experiment. From days 0 to 60, the THI exceeded 70. Blood samples were collected from the jugular vein of each calf at days 0, 15, 30, 45 and 60. Serum albumin and total protein decreased (p<0.05) in CON and VC calves with age. Serum glutamic-oxaloacetic transaminase concentrations were not affected by treatments. Serum creatinine, albumin and glutamic-pyruvic transaminase concentrations were higher in calves in the VC group than the CON group. While red blood cells, hemoglobin and hematocrit were lower (p<0.05) in VC calves, mean corpuscular volume, mean corpuscular hemoglobin, red blood cell distribution width and mean platelet volume were higher (p<0.05) in these VC supplemented calves. Leukocyte parameters including white blood cells and full term for lymphocytes were not affected by the treatments. Also, serum cortisol was not affected by treatments. At day 15, 30 and 45, the total VC in plasma was higher (p<0.05) in calves fed with VC. In conclusion, serum cortisols were not affected by plasma VC concentration, while some blood parameters were positively influenced in calves fed with VC.

• Journal of Bio-Environment Control
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• v.18 no.1
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• pp.67-73
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• 2009

This study was conducted to gather the basic data on making good use of a kind of groundsel (Ligularia fischeri). We have made methanol extracts from Ligularia fischeri and have also determined the effects of extracting temperature and time on the physiological activities of methanol extracts from Ligularia fischeri. Total phenolic compound and flavonoid contents in the methanol extracts from Ligularia fischeri at the extracting concentration of $1,000mg{\cdot}L^{-1}$ were $75.8-297.7mg{\cdot}L^{-1}$ and $45.6-173.6mg{\cdot}L^{-1}$. Total phenolic compound and flavonoid contents, and DPPH radical scavenging activities were most increased when Ligularia fischeri was extracted with methanol at $95^{\circ}C$ for 6 hours, however, nitrite radical scavenging activities were extremely increased at $75^{\circ}C$ for 12 hours by 97.4%. At $200mg{\cdot}L^{-1}$ and $400mg{\cdot}L^{-1}$ methanol extracting concentration, the hyperplasia of lung cancer cells (Calu-6) and stomach cancer cells (SNU601) were effectively inhibited over 90%. Consequently, it was assumed that Ligularia fischeri was a functional vegetable with a higher physiological activities. Making the processed foods, it had better make the extracts from Ligularia fischeri with methanol at $95^{\circ}C$ for 6 hours.