• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.111-117
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• 2019

This study proposed the fabrication and deposition of high purity crystalline $core-TiO_2/shell-Al_2O_3$ nanoparticles. Morphological properties of $core-TiO_2$ and coated $shell-Al_2O_3$ were confirmed by transmission electron microscope (TEM) and transmission electron microscope - energy dispersive spectroscopy (TEM-EDS). The electrical properties of the prepared $core-TiO_2/shell-Al_2O_3$ nanoparticles were evaluated by applying them to a working electrode of a Dye-Sensitized Solar Cell (DSSC). The particle size, growth rate and the main crystal structure of $core-TiO_2$ were analyzed through dynamic light scattering system (DLS), scanning electron microscope (SEM) and X-ray diffraction (XRD). The $core-TiO_2$, which has a particle size of 17.1 nm, a thin film thickness of $20.1{\mu}m$ and a main crystal structure of anatase, shows higher electrical efficiency than the conventional paste-based dye-sensitized solar cell (DSSC). In addition, the energy conversion efficiency (6.28%) of the dye-sensitized solar cell (DSSC) using the $core-TiO_2/shell-Al_2O_3$ nanoparticles selectively controlled to the working electrode is 26.1% higher than the energy conversion efficiency (4.99%) of the dye-sensitized solar cell (DSSC) using the conventional paste method.

• Composites Research
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• v.35 no.3
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• pp.139-146
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• 2022

In this study, we study fabrication methods suitable for CNT fibers-based composite. We try to fabricate a composite material using a small amount of CNT fiber preparation of woven fabrics or stitched unidirectional fabrics consisting of CNT fiber is not achievable currently. The composite materials on the basis of CNT fibers have been mainly manufactured filament winding method due to productivity issues and difficulties in composite processes. We develop a new method to prepare CNT fibers-based composite using resin infiltrated CNT fibers-based films. Because CNT fibers have numerous nanopores inside, unnecessary resin can remain after curing and decrease the mechanical properties of the composites. To remove the excess resin, pressure should be applied during the process, but the pressure applied through VaRTM was not enough to remove the excess resin. To obtain the composite with high ratio of CNT fibers, higher pressure using hot press machine and foams next to the resin-infiltrated CNT fibers are necessary. We can obtain the composite having a mass ratio of 58.5 wt% based on the new suggested method and diluted epoxy. The specific strength of the composite reach 0.525 N/tex. This study presents a new process method that can be applied to the manufacturing of CNT fiber composite materials in the future.

• Membrane Journal
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• v.32 no.2
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• pp.150-162
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• 2022

In the field of water treatment and pharmaceutical bio an alumina hollow fiber membrane used for mixture separation. However, due to the lack of strengths it is very brittle to handle and apply. Therefore, it is necessary to study and improve the bending strength of the membrane to 100 MPa or more. In this study, as the mixing ratio of the nano-particles increased to 0, 1, 3, and 5 wt%, the viscosity of the fluid mixture increased. The pore structure of the hollow membrane produced by interrupting the diffusion exchange rate of the solvent and non-solvent during the spinning process suppresses the formation of the finger-like structure and gradually increases the ratio of the sponge-like structure to improve the membrane mechanical strength to more than 100 MPa. As a result, an interparticle space was ensured to improve the porosity of the sponge-like structure with high permeability, and it showed excellent N2 permeability of about 100000 GPU and high water permeability of 3000 L/m² h. Therefore, it can be concluded, that the addition of γ-Al₂O₃ nanoparticles as sintering aid is an important method to enhance the mechanical strength of the α-alumina hollow fiber membrane to maintain high permeability.

• Membrane Journal
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• v.33 no.4
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• pp.149-157
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• 2023

Covalent organic frameworks (COFs) have shown promise in various applications, including molecular separation, dye separation, gas separation, filtration, and desalination. Integrating COFs into membranes enhances permeability, selectivity, and stability, improving separation processes. Combining COFs with single-walled carbon nanotubes (SWCNT) creates nanocomposite membranes with high permeability and stability, ideal for dye separation. Incorporating COFs into polyamide (PA) membranes improves permeability and selectivity through a synthetic interfacial strategy. Three-dimensional COF fillers in mixed-matrix membranes (MMMs) enhance CO₂/CH₄ separation, making them suitable for biogas upgrading. All-nanoporous composite (ANC) membranes, which combine COFs and metal-organic framework (MOF) membranes, overcome permeance-selectivity trade-offs, significantly improving gas permeance. Computational simulations using hypothetical COFs (hypoCOFs) demonstrate superior CO₂ selectivity and working capacity relevant for CO₂ separation and H₂ purification. COFs integrated into thin-film composite (TFC) and polysulfonamide (PSA) membranes enhance rejection performance for organic contaminants, salt contaminants, and heavy metal ions, improving separation capabilities. TpPa-SO₃H/PAN covalent organic framework membranes (COFMs) exhibited superior desalination performance compared to traditional polyamide membranes by utilizing charged groups to enable efficient desalination through electrostatic repulsion, suggesting their potential for ionic and molecular separations. These findings highlight COFs' potential in membrane technology for enhanced separation processes by improving permeability, selectivity, and stability. In this review, COF applied for the separation process is discussed.

• Journal of Life Science
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• v.29 no.6
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• pp.653-661
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• 2019

The first small interfering RNA (siRNA) therapeutics have recently been approved by the Food and Drug Administration in the U.S., and the demand for a new RNA therapeutics bioanalysis method-which is essential for pharmacokinetics, including the absorption, distribution, metabolism, and excretion of siRNA therapeutics-is rapidly increasing. The stem-loop real-time qPCR (RT-qPCR) assay is a useful molecular technique for the identification and quantification of small RNA (e.g., micro RNA and siRNA) and can be applied for the bioanalysis of siRNA therapeutics. When the anti-HPV E6/E7 siRNA therapeutic was used in preclinical trials, the established stem-loop RT-qPCR assay was validated. The limit of detection was sensitive up to 10 fM and the lower limit of quantification up to 100 fM. In fact, the reliability of the established test method was further validated in three intra assays. Here, the correlation coefficient of $R^2$>0.99, the slope of -3.10 ~ -3.40, and the recovery rate within ${\pm}20%$ of the siRNA standard curve confirm its excellent robustness. Finally, the circulation profiles of siRNAs were demonstrated in rat serum, and the pharmacokinetic properties of the anti-HPV E6/E7 siRNA therapeutic were characterized using a stem-loop RT-qPCR assay. Therefore, the stemloop RT-qPCR assay enables accurate, precise, and sensitive siRNA duplex quantification and is suitable for the quantification of small RNA therapeutics using small volumes of biological samples.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.2
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• pp.199-208
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• 2019

This study reports water-resistant oil-in-water (O/W) emulsion-based sunscreening formulations prepared using a poly(ethylene glycol)-poly(${\varepsilon}$-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG) triblock polymeric surfactant. As a result of a variety of outdoor recreational activities such as swimming and hiking, consumer needs for development of advanced water-resistant sunscreen formulations are increasing. Water-resistant sunscreens are mostly based on water-in-oil (W/O) emulsions, because they should not be wiped off by water or sweat. However, the W/O emulsion formulations have a disadvantage in that the feeling of use is oily and difficult to remove. On the other hand, the O/W emulsion formulations are excellent in achieving the better skin feel as well as the easier removal. However, it is difficult to provide the O/W emulsion formulations with the water-repelling performance, since re-emulsification likely occurs upon getting touch with water. To solve this problem, this study proposes a O/W emulsion-based sunscreen formulation, a triblock polymeric surfactant having relatively high interfacial tension HLB value (~ 10). This allows the sunscreen formulations to exhibit the improved water repellence function by preventing their re-emulsification. The sunscreen formation system prepared in this study would be useful for diversification of functional sunscreen products, taking advantages of its excellent emulsion stability, UV protection performance, long lasting water-resistant function and selective cleansing effect with only foam cleanser.

• Science of Emotion and Sensibility
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• v.24 no.4
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• pp.129-138
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• 2021

This study aimed to determine the effects of the shape and attachment position of stretchable textile sensors coated with carbon nanotube on their performance when used to measure children's joint movements. Moreover, the child-safe requirements for fabric motion sensors are established. The child participants were advised to wear integrated clothing equipped with the sensors of various shapes (rectangular and boat-shaped) and attachment positions (at the knee and elbow joints or 4 cm below the joints). The voltage change induced by the elongation and contraction of the fabric sensors was determined for arm and leg flexion-extension motions at 60 deg/s (three measurements of 10 repeats each for 60°and 90°angles, for a total of 60 repetitions). Their dependability was determined by comparing the fabric motion sensors to the associated acceleration sensors. The experimental results indicate that the rectangular-shaped sensor affixed 4 cm below the joint is the most effective fabric motion sensor for measuring children's arm and leg motions. In this study, we designed a textile sensor capable of tracking children's joint motion and analyzed the sensor shape and attachment position on motion sensing clothing. We demonstrated that flexible fabric sensors integrated into garments may be used to detect the joint motions of the human body.

• Journal of Life Science
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• v.32 no.1
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• pp.63-69
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• 2022

The thioredoxin reductase (TrxR) system is essential for cell survival and function by playing a pivotal role in maintaining homeostasis of cellular redox and regulating signal transduction pathways. The TrxR system comprises thioredoxin (Trx), TrxR, and nicotinamide adenine dinucleotide phosphate. Trx reduced by the catalytic reaction of the TrxR enzyme reduces downstream proteins, resulting in protection against oxidative stress and regulation of cell differentiation, growth, and death. Cancer cells survive by improving their intracellular antioxidant capacity to eliminate excessively generated reactive oxygen species (ROS) due to infinite cell proliferation and a high metabolic rate. Therefore, cancer cells have high dependence and sensitivity to antioxidant systems, suggesting that focusing on TrxR, a representative antioxidant system, is a potential strategy for cancer therapy. Several studies have revealed that TrxR is expressed at high levels in various types of cancers, and research on anticancer activity targeting the TrxR system is increasing. In this review, we discuss the feasibility and value of the TrxR system as a strategy for anticancer activity research by examining the relationship between the function of the intracellular TrxR system and the development and progression of cancer, considering the anticancer activity and mechanism of TrxR inhibitors.

• The Korea Journal of Herbology
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• v.29 no.2
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• pp.39-45
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• 2014

Objectives : The purpose of this study was to investigate antiaging and antioxidant effects on cultured human skin fibroblast with 80% ethanol extracts of plants including of stem of Dendropanax morbifera, Corni fructus and Lycii Fructus. Methods : An ethanol extract of three medicinal plants including stem of Dendropanax morbifera, Corni fructus and Lycii Fructus. Extracts were assessed to determine the mechanism of antioxidant and antiaging activities. Antioxidant activity of extract was evaluated by two different assays as 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and super oxide dismutase (SOD) like activities. These extracts were tested for cell viability on HS68 skin fibroblast by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. We investigated the effects of Ultraviolet-B irradiation on cytotoxicity, type 1 collagen, elastin level and oxidative damage in cultured human skin fibroblast (HS68). Recently, many studies have reported that elastin is also involved in inhibiting or repairing wrinkle formation, although collagen is a major factor in the skin wrinkle formation. Results : The extracts obtained dose-dependently increased the scavenging activity on DPPH radical scavenging activity and SOD like activity. The extracts of complex herbal medicine showed low cytotoxicity as more than 100% cell viability in 100ppm/ml concentration. HS68 fibroblasts were survived 70% at 120 $mJ/cm^2$ UVB irradiation and treated tumor necrosis factor (TNF)-alpha. The levels of aging factors and cytotoxicity were decreased by ethanol extract of complex herbal medicine. Conclusions : These results suggest that ethanol extracts of complex medicinal plants of including of stem of Dendropanax morbifera, Corni fructus and Lycii Fructus may have value as the potential antioxidant and antiaging medicinal plant.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.188-194
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• 2022

This work presents a non-destructive and straightforward approach to assemble a large-scale conductive electronic film made of a pre-treated single-walled carbon nanotube (SWCNT) solution. For effective electron transfer between the immobilized enzyme and SWCNT electronic film, we optimized the pre-treatment step of SWCNT with p-terphenyl-4,4"-dithiol and dithiothreitol. Glucose oxidase (GOx, a model enzyme in this study) was immobilized on the SWCNT electronic film following the positively charged polyelectrolyte layer deposition. The glucose detection was realized through effective electron transfer between the immobilized GOx and SWCNT electronic film at the negative potential value (-0.45 V vs. Ag/AgCl). The SWCNT electronic film-based glucose biosensor exhibited a sensitivity of 98 ㎂/mM·cm². In addition, the SWCNT electronic film biosensor showed the excellent selectivity (less than 4 % change) against a variety of redox-active interfering substances, such as ascorbic acid, uric acid, dopamine, and acetaminophen, by avoiding co-oxidation of the interfering substances at the negative potential value.