• Elastomers and Composites
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• v.55 no.2
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• pp.95-102
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• 2020

Currently, peroxide cure is a widely used cure system for rubber materials. To improve its effectivity, co-agents are used to enhance the peroxide efficiency and mechanical properties of rubber materials. Co-agents are multifunctional organic compounds that are highly reactive towards free radicals. These co-agents provide higher cross-link densities for a given peroxide concentration and improve the mechanical properties of peroxide-cured rubber composites. In this study, trimethylolpropane trimethacrylate (TMPTMA) and high vinyl 1,2-polybutadiene (HVPBD) were used as co-agents. In order to obtain a concentration that achieves a favorable balance between mechanical properties and co-agent concentration, this research investigated the effects of co-agent content on the curing characteristics, chemical structures, and mechanical properties of HNBR composites. Additionally, the heat aging properties and compression sets of HNBR composites were investigated. Based on the results, we found that the HNBR composites with TMPTMA co-agents exhibited higher Shore A hardness and 10% modulus and better heat aging resistance and compression set than that of the HVPBD co-agent. The heat aging resistance and compression set deteriorated with increasing HVPBD content.

• Applied Chemistry for Engineering
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• v.34 no.5
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• pp.522-528
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• 2023

In this work, adhesive tapes were prepared for the dicing process in semiconductor manufacturing. Compounds with different numbers of photoreactive groups (f = 1 to 3) were synthesized and incorporated into acrylic copolymers to formulate UV-curable acrylic adhesives. Structural confirmation of the synthesized photoreactive compounds (f = 2 or 3) was performed using nuclear magnetic resonance (NMR) spectroscopy. The introduction of the photoreactive compounds into the acrylic adhesive was accomplished by urethane reactions, and the successful synthesis of the UV-curable acrylic adhesive was verified by Fourier transform infrared (FT-IR) measurements. To evaluate the performance of the adhesive, the peel strength was evaluated before and after UV irradiation using a silicon wafer as a substrate. The adhesive exhibited high peel strength (~2000 gf/25 mm) before UV exposure, which was significantly reduced (~5 gf/25 mm) after UV exposure. Interestingly, the adhesive containing multifunctional photoreactive compounds showed the most significant reduction in peel strength. In addition, surface residue measurements by field emission scanning electron microscopy (FE-SEM) showed minimal surface residue (~0.2%) after UV exposure. Overall, these results contribute to the understanding of the behavior of UV-curable acrylic adhesives and pave the way for potential applications in semiconductor manufacturing processes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.4
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• pp.315-320
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• 2002

The multifunctional compound such as conjugated linoleic acid (CLA) was used to producing of functional larval rockfish. Artemia, livefoods for larval fish, enriched with highly unsaturated fatty acids (HUFA) and CLA ($0.5\%$, $1.0\%$, $2.5\%$ and $5.5\%$ group) was fed to larval rockfish. Artemia, enriched with $2.5\~5.0\%$ of CLA, negatively affects the quality of larval rockfish. But $1.0\%$ CLA fed group shown to good specific growth rate, feed efficiency, n-3/n-6 PUFA ratio, DHA/EPA ratio and hematology results. The CLA deposited in muscle lipids of larval rockfish was reached 6.57 to $19.69\%$.

• Journal of Microbiology and Biotechnology
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• v.26 no.6
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• pp.999-1010
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• 2016

Ganoderma lucidum BCCM 31549 has a long established role for its therapeutic activities. In this context, much interest has focused on the possible functions of the (1,3)-β-D-glucan (G) produced by these cultures in a stirred-tank bioreactor and extracted from their underutilized mycelium. In the existing study, we report on the systematic production of G, and its sulfated derivative (GS). The aim of this study was to investigate G and its GS from G. lucidum in terms of their antibacterial properties and cytotoxicity spectrum against human prostate cells (PN2TA) and human caucasian histiocytic lymphoma cells (U937). ¹H NMR for both G and GS compounds showed β-glycosidic linkages and structural similarities when compared with two standards (laminarin and fucoidan). The existence of characteristic absorptions at 1,170 and 867 cm^-1 in the FTIR (Fourier Transform Infrared Spectroscopy) for GS demonstrated the successful sulfation of G. Only GS exhibited antimicrobial activity against a varied range of test bacteria of relevance to foodstuffs and human health. Moreover, both G and GS did not show any cytotoxic effects on PN2TA cells, thus helping demonstrate the safety of these polymers. Moreover, GS showed 40% antiproliferation against cancerous U937 cells at the low concentration (60 μg/ ml) applied in this study compared with G (10%). Together, this demonstrates that sulfation clearly improved the solubility and therapeutic activities of G. The water-soluble GS demonstrates the potential multifunctional effects of these materials in foodstuffs.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1081-1087
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• 2018

This study was carried out to investigate the effects of the extracts of 80% EtOH and EtOAc, BuOH, and D.W in Korean native Hypsizygus marmoreus. Antioxidation and antioxidant analysis to provide the possibility of a multifunctional cosmetic raw material. As a result of analyzing the cytotoxicity of the sample using the animal cell line HaCaT cell, it was confirmed that the toxicity of the sample hardly affected the cells. The inhibition rate of elastase was 30.41% at 10% of sample concentration and inhibition activity of collagenase was 11.65% at 1% of sample concentration. Hypsizygus marmoreus showed better antioxidant activity than similar mushroom. The total phenol contents of the fractions were 778.4 mg and 2.59 mg per 1 g of white mushroom, confirming its potential as a natural antioxidant. As a result, the extract of Hypsizygus marmoreus is considered to be highly valuable as a natural cosmetic material having antioxidant and antioxidant functions.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.2
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• pp.206-218
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• 2020

Located mostly inside the megacity of Busan, the Busan Southern Port is a multifunctional port with various nearby industry activities, including a joint fish market, ship repair facilities, and fishing boat facilities. If toxic chemicals generated by the industrial activities continue to flow into and accumulate in the sediment of the port, they can affect aquatic ecosystems and humans. Therefore, in this study, distribution levels and potential influent sources of organic pollutants, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and butyltin compounds (BTs), in the sediment were investigated. The sediment samples were collected from eight sampling sites in November 2013 (first phase) and November 2014 (second phase). The mean concentrations of PAHs, PCBs, and BTs in the first and second sampling phages were 4174.0 ng/g-dry wt. and 1919.0 ng/g-dry wt., 166.3 ng/g-dry wt. and 21 ng/g-dry wt., and 50.9 ng/g-dry wt. and 30.8 ng/g-dry wt., respectively. The concentrations of the organic pollutants detected in the seabed sediments were lower in the second phase than in the first phase. In this study, the inflow sources of PAHs, PCBs, and BTs were found to be combustion, land, and municipal sewage or industrial wastewater, respectively.

• Journal of the Korean Wood Science and Technology
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• v.41 no.3
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• pp.234-246
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• 2013

It was found that test piece heated rapidly by 3 kW microwave for 5 minutes satisfies the targeted temperature and the percentage of moisture content, and the highest rate of weight increase is obtained in case of 120 minute immersion in the mixture of phosphates and heterocyclic compounds, from the result of such analysis as: kiln drying schedule, flame retardent by flammability test, insect resistance by termites, and permeability of combined penetrant for the wood after assigning multifunctional finish by immersing conifer structural frame, which is used for the frame work of wooden house and indoor/outdoor finishing in flame retardant and insect repellent materials mixture with the remaining heat of microwave. In addition, after a test of flame retardent treated item, it was identified that every mixture of phosphates corresponds with the standards of flame retardent, and upon investigation of moritality of 7 days after putting termites, it was showed that test piece immersed in the mixture of phosphates and heterocyclic compounds has the best characteristics, showing over 96% of high moritality. From the analysis of inward permeability of combined penetrant for the wood, it was decided that excellent performance in the flame retardent and insect resistance of the wood revealed due to full penetration of combined penetrant as it was found that combined penetrant penetrated through the whole inner cells of the wood.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1028-1034
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• 1999

Poly(lactic acid) is expected to be one of the most promising biodegradable polymers. However, the high molecular weight polymer could be obtained by ring-opening polymerization process conventionally, which raises the production cost and decreases the final yield. In this study, linear and star-shaped poly(L-lactic acid)s were prepared by direct solution polycondensation method and their physical and thermal properties were examined. Tin compounds were found to be effective catalyst for the preparation of high molecular weight polymers. When 0.2g (0.5 wt % of monomer) of $SnCl_2$ and 100 mL of p-xylene were used, the polymer yield and molecular weight were relatively high. As a means to obtain higher molecular weight polymer easily in the direct polycondensation system, dipentaerythritol(dipet) or pentaerythritol(pet) was introduced as a multifunctional branching monomer to provide a star-shaped poly(lactic acid). Moderately high molecular weight polymers with the inherent viscosity values up to 1.14 dL/g(weight-average molecular weight of about 140000 by GPC) were obtained and could be cast strong and transparent films.

• Journal of Life Science
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• v.24 no.5
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• pp.498-504
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• 2014

Mammalian hyaluronidases (HAase, EC 3.2.1.35) are a family of enzymes that hydrolyse N-acetyl-D-glucosamine (1-4) glycosidic bonds in hyaluronic acid, which is found in skin, cartilage, and the vitreous body. Although HAase is generally present in an inactive form within subcellular lysosomes, it is released in an active form in some types of inflammation and tissue injuries, thereby contributing to the inflammatory response. The HAase inhibitory activity of 500 methanolic extracts of 500 species from medicinal plants was screened using a Morgan microplate assay. The viscosity of the hyaluronic acid was measured with an Ubbelohde viscometer. Three MeOH extracts inhibited more than 50% of HAase activity at a concentration of 2 mg/ml. HAase inhibitory rates (%) of three species of medicinal plant extracts, Styrax japonica, Deutzia coreana, and Osmanthus insularis were 57.28%, 53.50%, and 53.19%, respectively. The rate of HAase inhibition of the extracts was dose dependent. In the HAase inhibitory assay using the Ubbelohde viscometer, the results were in good agreement with the results from the Morgan assay. The results suggest that HAase inhibitory compounds extracted from the stem of S. japonica, D. coreana, and O. insularis might be multifunctional and prevent the degradation of hyaluronic acid and the induction of allergic reactions and inflammation.

• Journal of Ginseng Research
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• v.42 no.3
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• pp.327-333
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• 2018

Background: Bioactive compounds in plant extracts are able to reduce metal ions to nanoparticles through the process of green synthesis. Panax ginseng is an oriental medicinal herb and an adaptogen which has been historically used to cure various diseases. In addition, the P. ginseng leaves-mediated gold nanoparticles are the value-added novel materials. Its potential as a cosmetic ingredient is still unexplored. The aim of this study was to evaluate the antioxidant, moisture retention and whitening properties of gold nanoparticles (PgAuNPs) in cosmetic applications. Methods: Cell-free experiments were performed to evaluate PgAuNP's antioxidant and moisture retention properties and inhibition activity on mushroom tyrosinase. Furthermore, in vitro cell cytotoxicity was evaluated using normal human dermal fibroblast and murine B16BL6 melanoma cells (B16) after treatment with increasing concentrations of PgAuNPs for 24 h, 48 h, and 72 h. Finally, in vitro cell assays on B16 cells were performed to evaluate the whitening effect of PgAuNPs through reduction of cellular melanin content and tyrosinase activity. Results: In vitro DPPH radical scavenging assay results revealed that PgAuNPs exhibited antioxidant activity in a dose-dependent manner. PgAuNPs exhibited moisture retention capacity and effectively inhibited mushroom tyrosinase. In addition, 3-(4,5-dimethyl-thiazol-2yl)-2,5-diphenyl tetrazolium bromide results revealed that PgAuNPs were not toxic to human dermal fibroblast and B16 cells; in addition, they significantly reduced melanin content, tyrosinase activity, and mRNA expression of melanogenesis-associated transcription factor and tyrosinase in B16 cells. Conclusion: Our study is the first report to provide evidence supporting that P. ginseng leaves-capped gold nanoparticles could be used as multifunctional ingredients in cosmetics.