• Biomolecules & Therapeutics
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• v.29 no.2
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• pp.211-219
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• 2021

Alopecia is a distressing condition caused by the dysregulation of anagen, catagen, and telogen in the hair cycle. Dermal papilla cells (DPCs) regulate the hair cycle and play important roles in hair growth and regeneration. Myristoleic acid (MA) increases Wnt reporter activity in DPCs. However, the action mechanisms of MA on the stimulation of anagen signaling in DPCs is not known. In this study, we evaluated the effects of MA on anagen-activating signaling pathways in DPCs. MA significantly increased DPC proliferation and stimulated the G2/M phase, accompanied by increasing cyclin A, Cdc2, and cyclin B1. To elucidate the mechanism by which MA promotes DPC proliferation, we evaluated the effect of MA on autophagy and intracellular pathways. MA induced autophagosome formation by decreasing the levels of the phospho-mammalian target of rapamycin (phospho-mTOR) and increasing autophagy-related 7 (Atg7) and microtubule-associated protein 1A/1B-light chain 3II (LC3II). MA also increased the phosphorylation levels of Wnt/β-catenin proteins, such as GSK3β (Ser9) and β-catenin (Ser552 and Ser675). Treatment with XAV939, an inhibitor of the Wnt/β-catenin pathway, attenuated the MA-induced increase in β-catenin nuclear translocation. Moreover, XAV939 reduced MA-induced effects on cell cycle progression, autophagy, and DPC proliferation. On the other hand, MA increased the levels of phospho (Thr202/Tyr204)-extracellular signal regulated kinases (ERK). MA-induced ERK phosphorylation led to changes in the expression levels of Cdc2, Atg7 and LC3II, as well as DPC proliferation. Our results suggest that MA promotes anagen signaling via autophagy and cell cycle progression by activating the Wnt/β-catenin and ERK pathways in DPCs.

• Journal of Powder Materials
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• v.28 no.2
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• pp.143-149
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• 2021

In this study, (GaN)_1-x(ZnO)_x solid solution nanoparticles with a high zinc content are prepared by ultrasonic spray pyrolysis and subsequent nitridation. The structure and morphology of the samples are investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The characterization results show a phase transition from the Zn and Ga-based oxides (ZnO or ZnGa₂O₄) to a (GaN)_1-x(ZnO)_x solid solution under an NH3 atmosphere. The effect of the precursor solution concentration and nitridation temperature on the final products are systematically investigated to obtain (GaN)_1-x(ZnO)_x nanoparticles with a high Zn concentration. It is confirmed that the powder synthesized from the solution in which the ratio of Zn and Ga was set to 0.8:0.2, as the initial precursor composition was composed of about 0.8-mole fraction of Zn, similar to the initially set one, through nitriding treatment at 700℃. Besides, the synthesized nanoparticles exhibited the typical XRD pattern of (GaN)_1-x(ZnO)_x, and a strong absorption of visible light with a bandgap energy of approximately 2.78 eV, confirming their potential use as a hydrogen production photocatalyst.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.4
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• pp.277-291
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• 2021

A mineral phase contained in a rock sample can be categorized into several crystal populations with distinct origins and crystal growth histories. A detailed textural and mineralogical investigation on a clinopyroxene megacryst-bearing porphyritic dike with glassy chilled margins (tachylyte) in the southeastern Ulleung Island was conducted to decipher its crystal populations. During this study, we have measured glass and mineral major element compositions using electron microprobe analyzer. Tachylyte has a homogeneous trachyandesitic composition without any significant alteration characteristics, suggesting that its composition may represent the original melt composition of the dike. Clinopyroxene and plagioclase larger than 0.5 mm are antecrysts equilibrated with a more primitive melt composition than trachyandesitic tachylyte. Meanwhile, clinopyroxene and plagioclase microlites (<0.5mm) are regarded as primocrysts crystallized in-situ. According to our results, all clinopyroxenes in the Stage I Dodong Basalt are sectored into basal and prismatic parts, whose compositional ranges systematically vary: [Mg+Si+Fe]_basal ↔ [Al+Ti+Na]_prism. Therefore, we suggest that the effect of the elemental partitioning caused by the clinopyroxene sector zonation in Stage I volcanism should be considered in the future works.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.6
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• pp.371-383
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• 2021

Steel-concrete single-leaf blast-resistant doors, having steel box and slab inside, are installed on the wall using supporting members such as hinges and latches. Several studies have been conducted on their deflection behavior in the same direction as that of the blast pressure, but studies on their deflection behavior in the opposite direction, that is, studies on negative deflection behavior are relatively insufficient. In this study, we conducted a parameter analysis using finite element analysis on blast-resistant doors, on their rebound behavior in the negative deflection phase. Results revealed that the plastic deformation of the door, and the change in momentum and kinetic energy during rebound, were major factors influencing the rebound behavior. Greater rebound force was developed on the supporting members in the impulsive region, than in the quasi-static region; due to the characteristics in the impulsive region, where the kinetic energy developed relatively greater than the strain energy. In the design process, it is necessary to consider excessive deformation that could occur in the supporting members as the rebound behavior progresses. Additionally, it was found that in the case of steel-concrete blast doors, the rebound force increased relatively more, when the effects of both rebound and negative blast pressure contributed to the negative deflection of the door. Since conditions for the occurrence of this superposition effect could vary depending on structural characteristics and explosion conditions, further investigation may be required on this topic.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.610-622
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• 2021

The DECOVALEX project is one of the representative international cooperative projects to enhance the understanding of the complex Thermo-Hydro-Mechanical-Chemical(THMC) coupled behavior in the high-level radioactive waste disposal system based on the numerical simulation. DECOVALEX-2023 is the current phase consisting of 7 tasks, and Task C aims to model the THM coupled behavior in the disposal system based on the Full-scale Emplacement (FE) experiment at the Mont-Terri underground rock laboratory. This study performs the numerical simulation based on the OGS-FLAC developed for the current study. In the numerical model, we emplaced the heater with constant power horizontally based on the FE experiment and monitored the pressure development, temperature increase, and mechanical deformation at the specific monitoring points. We monitored the capillary pressure as the primary effect inducing the flow in the buffer system, and thermal stress and pressurization were dominant in the surrounding rocks' area. The results will also be compared and validated with the other participating groups and the experimental data further.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3250-3259
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• 2022

A new approach to the use of rice straw as a difficult-to-recycle agricultural waste was proposed. Potassium aluminosilicate was obtained by spark plasma sintering as an effective material for subsequent immobilization of ¹³⁷Cs into a solid-state matrix. The sorption properties of potassium aluminosilicate to ¹³⁷Cs from aqueous solutions were studied. The effect of the synthesis temperature on the phase composition, microstructure, and rate of cesium leaching from samples obtained at 800-1000 ℃ and a pressure of 25 MPa was investigated. It was shown that the positive dynamics of compaction was characteristic of glass ceramics throughout the sintering. Glass ceramics RS-(K,Cs)AlSi₃O₈ obtained by the SPS method at 1000 ℃ for 5 min was characterized by a high density of ~2.62 g/cm³, Vickers hardness ~ 2.1 GPa, compressive strength ~231.3 MPa and the rate of cesium ions leaching of ~1.37 × 10^-7 g cm^-2·day^-1. The proposed approach makes it possible to safe dispose of rice straw and reduce emissions into the atmosphere of microdisperse amorphous silica, which is formed during its combustion and causes respiratory diseases, including cancer. In addition, the obtained is perspective to solve the problem of recycling long-lived ¹³⁷Cs radionuclides formed during the operation of nuclear power plants into solid-state matrices.

• Journal of Korea Water Resources Association
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• v.55 no.9
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• pp.679-686
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• 2022

As the occurrences of flash floods have increased due to climate change, faster and more accurate precipitation observation using X-band radar has become important. Therefore, the Ministry of Environment installed two dual-pol X-band radars at Samcheok and Uljin. The radar data used in this study were obtained from two different elevation angles and composed to reduce the shielding effect. To obtain quantitative rainfall, quality control (QC), K_DP retrieval, and Hybrid Surface Rainfall (HSR) methods were sequentially applied. To improve the accuracy of the quantitative precipitation estimation (QPE) of the X-band radar, we retrieved parameters for the relationship between rainfall rate and specific differential phase, which is commonly called the R-K_DP relationship; hence, an empirical approach was developed using multiple rain gauges for those two radars. The newly suggested relationship, R = 27.4K^0.81_DP, slightly increased the correlation coefficient by 1% more than the relationship suggested by the previous study. The root mean square error significantly decreased from 3.88 mm/hr to 3.68 mm/hr, and the bias of the estimated precipitation also decreased from -1.72 mm/hr to -0.92 mm/hr for overall cases, showing the improvement of the new method.

• Korean Journal of Poultry Science
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• v.49 no.4
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• pp.221-228
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• 2022

Major egg white proteins and their hydrolysates serve as functional food ingredients that have certain metal-chelating properties. Employing egg white proteins and their hydrolysates to scavenge dietary oxalates is anticipated to have beneficial effect in the prevention of kidney stones. The objective of this study was to determine the biogenic oxalate-chelating activity of ovalbumin, ovomucin, and ovotransferrin and their hydrolysates. To prepare oxalate extracts, 30 mL of 0.25 N HCl was added to separately to 0.5 g of dried spinach and starfruit powders followed by boiling for 15 min, and after cooling, the addition of a further 20 mL of 0.25 N HCl. Having prepared these extracts, ovalbumin, ovomucin, and ovotransferrin and their hydrolysates were separately mixed with oxalate extracts and incubated at 3℃ for 24 h. Following centrifugation, supernatants were analyzed by HPLC using a reverse-phase C18 column coupled with a diode array detector. We found that all assessed proteins and their hydrolysates showed biogenic oxalate-chelating activity against the oxalates of spinach. In contrast, however, only ovalbumin, ovalbumin-hydrolysate, and ovomucin showed chelating activity (57.10%±8.84%, 85.44%±5.30%, 73.20%±4.13%, respectively) against the oxalates of starfruit (P<0.05). Overall, hydrolyzed ovalbumin was identified as the most effective chelator of the oxalates both spinach and starfruit. In this study, we thus established that the assessed egg white proteins and their hydrolysates have oxalate-chelating activity in vitro, thereby indicating that these compounds have potential utility as nutraceuticals for the chelation of dietary oxalate. However, further research will be necessary to verify their oxalate-chelating activities against different fruits and vegetables and under specific in vivo conditions and against purified oxalate.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.4
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• pp.136-142
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• 2022

The crystal structure, grain growth behavior, and dielectric properties of BaTiO₃ have been studied with the addition of Dy₂O₃. The powders were synthesized at ratios of (100-x)BaTiO₃-xDy₂O₃ (mol%, x = 0, 0.5, 1.0, 2.0) by a conventional solid-state synthesis, and the powder compacts were sintered at 1250℃ for 2 hours in air. As the amount of added Dy₂O₃ was increased, the crystal structure of the sintered samples changed from a tetragonal to a pseudo-cubic structure, and the tetragonality decreased. In addition, a secondary phase of Ba₁₂Dy_4.67Ti₈O₃₅ appeared when Dy₂O₃ was added. The average grain size after sintering decreased and abnormal grains appeared as the amount of Dy₂O₃ increased. It can be explained that the grain growth behavior of the Dy₂O₃ added-BaTiO₃ occurs due to the two-dimensional nucleation and growth, and is governed by the interface reaction. Further, the correlation between crystal structure, microstructure, and dielectric properties was discussed.

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.188-193
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• 2022

The Korean mint (Agastache rugosa Kuntze) is used as a leaf vegetable. Therefore, it is important to improve the quality and quantity of leaves by maintaining vegetative growth. When the development of a plant is switched from vegetative to reproductive growth, leaf development may be lowered, leading to a decrease in marketability. Therefore, this study was conducted to investigate the effect of the photoperiod on the flowering characteristics and inflorescence development of the Korean mint to select an appropriate photoperiod for leaf production. The seeds were sown in 105-cell trays on 29 November 2021, and planted in each pot on 27 December 2021, when four main leaves appeared. After planting, the light/dark period was adjusted to 10/14hrs, 12/12hrs, 14/10hrs, 16/8hrs. After 19 days of planting, the first flowering occurred in 10/14hrs, which had a short photoperiod, and the 12/12hrs had 20 days for flowering, and other treatments had 21 days. In addition, it was confirmed that the Korean mint has the characteristics of facultative quantitative short-day plant, through the increase in the development of inflorescences as the light period is shorter than the dark period. As for the growth of Korean mint, the longer the photoperiod, the higher values were shown with leaf length, number of leaves, fresh weight, dry weight, and leaf area of the shoot. Therefore, it is considered that 14 h or more light period is suitable for increasing the productivity of Korean mint as a leafy vegetable.