• Journal of the Korean Society of Tobacco Science
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• v.17 no.2
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• pp.103-108
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• 1995

Antibiotic and physico-chemical properties of an active compound from actinomycetes isolate G-37, of which the culture filtrate had an inhibitory effect against tobacco mosaic virus(W) infection, were examined. The active compound, which was purified by ethylacetate extraction, silica gel column chromatography, preparative thin layer chromatography, and high performance liquid chromatography, showed strong antibacterial activities especially against Gram-positive bacteria including Bacillus subtillis, Sarcina lutea and Staphylococcus aureus. From the IH-NMR, FAB/RfS, UV spectral data, and physicochemical properties, the active compound of G-37 appears to belong to a peptide antibiotic group. Among the known peptide antibiotics in the antibiotic group, No. 280, A-30912, and Taitomycin showed molecular weights and ultra violet spectrum similar to those of the active compound from G-37, but was not identical to the compound, which suggests that it may be a new peptide antibiotics.

• Microbiology and Biotechnology Letters
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• v.24 no.5
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• pp.574-578
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• 1996

In the course of screening for the antifungal compounds against Candida albicans, an antifungal compound (F1480) was isolated from the culture broth of Aspergillus candidus F1484. Isolation and purification of compound F1484 were performed using ethyl acetate extraction, silica gel column chromatography, ODS column chromatography, and preparative HPLC. The structure of compound F1484 was determined by the spectroscopic analyses of EI-MS, $^{13}$C, $^{1}$H-NMR, DEPT, HMQC, and HMBC. This compound appeared to have a structure of antifungal agent, chloroflavonin. In addition to antifungal activities against the yeast phase of Candida species, compound F1484 showed cytotoxic effect against various human tumor cell lines.

• Journal of Applied Biological Chemistry
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• v.65 no.3
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• pp.215-219
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• 2022

The flowers of Cosmos bipinnatus were extracted with solvent made with methanol:water (4:1) and the concentrates were partitioned into ethyl acetate (EtOAc), n-butanol (n-BuOH), and water (H₂O) fractions. The octadecyl silica gel (ODS) and silica gel (SiO₂) column chromatographies were repeated for the EtOAc fraction to isolated of two phenolic compounds. The chemical structure of the isolated compounds were identified as benzyl O-β-ᴅ-glucopyranoside (1), and 2-phenylethyl O-β-ᴅ-glucopyranoside (2) through spectroscopic datas such as nuclear magnetic resornance, infrarad spectroscopy, and mass spectroscopy. These two compounds were first isolated from C. bipinnatus flowers through this study. To evaluate the anti-atopic activity of the two isolated compounds using a HaCaT cell line induced by ultraviolet light, several experiments were conducted and neither both compounds showed toxicity in the concentration range of 1 to 1,000 ㎍/mL. In the results of anti-atopic activity through Thymus and activation regualted chemokine (TARC) assay, both compounds showed dose-dependent TARC inhibitory activity. In particular, compound 1 showed significant activity even in a low concentration range of 10 ㎍/mL, and in different concentration ranges. Also compound 1 showed higher inhibitory activity than other compound, confirming that the anti-atopic activity was the most excellent. Based on these results, it is considered that it can be used as a functional cosmetic material.

• Polymer(Korea)
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• v.33 no.5
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• pp.452-457
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• 2009

Hybrid nanomaterials consisting of multi-walled carbon nanotube(MWNT) and/or PEDOT of conductive polymer were prepared in this study. In the presence of catalyst and ligand, the MWNT-Br compound prepared by the successive surface treatment reaction was mixed with MMA to initiate the atom transfer radical polymerization process. PMMA was covalently linked to the surface of MWNT for the formation of MWNT/PMMA nanocomposites. The EDOT and oxidant were added in the aqueous emulsion of PS produced via a miniemulsion polymerization process and then it proceeded to carry out the oxidative chemical polymerization of EDOT for the preparation of PEDOT/PS nanoparticles with the core-shell structure. The aqueous dispersion of PEDOT:poly(styrene sulfonate) (PSS) was mixed with the silica particles treated with a silane compound and thus PEDOT:PSS-clad silica nanoparticles were prepared by the surface chemistry reaction. The hybrid nanomaterials were analyzed by using TEM, FE-SEM, TGA, EDX, UV, and FT-IR.

• Elastomers and Composites
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• v.53 no.2
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• pp.39-47
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• 2018

Styrene-butadiene rubber (SBR) is widely used in tire treads due to its excellent abrasion resistance, braking performance, and reasonable cost. Depending on the polymerization method, SBR is classified into solution-polymerized SBR (SSBR) and emulsion-polymerized SBR (ESBR). ESBR is less expensive and environmentally friendlier than SSBR because it uses water as a solvent. A higher molecular weight is also easier to obtain in ESBR, which has advantages in mechanical properties and tire performance. In ESBR polymerization, a surfactant is added to create an emulsion system with a hydrophobic monomer in the water phase. However, some amount of surfactant remains in the ESBR during coagulation, making the polymer chains in micelles clump together. As a result, it is well-known that residual surfactant adversely affects the physical properties of silica-filled ESBR compounds. However, researches about the effect of residual surfactant on the physical properties of ESBR are lacking. Therefore, in this study we compared the effects of remaining surfactant in ESBR on the mechanical properties of silica-filled and carbon black-filled compounds. The crosslinking density and filler-rubber interaction are also analyzed by using the Flory-Rehner theory and Kraus equation. In addition, the effects of surfactant on the mechanical properties and crosslinking density are compared with the effects of TDAE oil (a conventional processing aid).

• Journal of Applied Biological Chemistry
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• v.64 no.4
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• pp.363-368
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• 2021

The fruits of tomato (Lycopersicon esculentum) were extracted with 70% aqueous methanol (MeOH) and the concentrates were partitioned into ethyl acetate (EtOAc), n-butanol (n-BuOH), and water (H₂O) fractions. The repeated silica gel (SiO₂) and octadecyl silica gel column chromatographies for the EtOAc fraction, whose activity was confirmed, led to isolation of one flavone compound. Nuclear magnetic resornance, infrarad spectroscopy, and mass spectroscopy (MS) revealed the chemical structure of the isolated compound, 5,7,3'-trihydroxy-6,4',5'-trimethoxyflavone (1). LC-MS/MS analysis determined the content level of compounds 1 in the MeOH extract to be 4.02±0.12 ㎍/mg and in the TME-10 fraction to be 0.96±0.03 ㎍/mg. Through this study, the antioxidantive capacity was confirmed by demonstrating that the L. esculentum extract and their fractions showing an increase in glutathione mean and a decrease in glutathione heterogeneity uniformly raises the intracellular glutathione level.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.8
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• pp.79-86
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• 2022

With the recent increase in the demand for electric vehicles, it is necessary to identify the high current safety of automobile parts. Among the automobile parts, the EPDM parts required colored parts from the existing black; therefore, it was necessary to change the basic filler from carbon black to silica. The rubber used in automobile parts is flexible and exhibits basic characteristics of high strength and elongation. However, as the filler is changed to silica, its physical properties, such as tensile strength and elongation, are lower than those of the existing carbon black base. Therefore, it is necessary to evaluate the mechanical properties with the addition of the EPDM compound using silica as a base without degrading the physical properties of EPDM. In this study, an experiment based on the additive content was performed using the mixture experimental planning method to analyze the mechanical properties according to the additive type and mixing ratio of silica-based EPDM. The mixing ratio of the four additives was set using a simplex lattice design, and the tensile strength, elongation, modulus 300%, and permanent compression reduction rate were analyzed for mechanical characteristics, and rheometer experiments were performed for vulcanization characteristics. Through statistical analysis of the measured data, the main effects and interactions of the EPDM-blended rubber additives were analyzed. These results can be used to derive a mixing ratio of additives that satisfies the required characteristics of the EPDM compound.

• Elastomers and Composites
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• v.56 no.4
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• pp.243-249
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• 2021

The demand for truck bus radial (TBR) tires with enhanced fuel efficiency and wear resistance have grown in recent years. In addition, as the issue of particulate matter and air pollution increases, efforts are being made to reduce the generation of particulate matter. In this study, we investigated the effect of varying the content of butadiene rubber (BR) on the properties of the rubber compounds and the amount of particulate matter in the TBR tire tread compound. Furthermore, we utilized carbon black in the NR/BR blend compounds owing to its excellent compatibility, and we used silica in the ENR-25/BR blend compounds because it can interact chemically with epoxide groups. The NR/BR blend compounds and the ENR-25/BR blend compounds were evaluated by varying their BR content between 20 phr and 30 phr. The results showed that the ENR-25/BR blend compounds had superior wear resistance than the NR/BR blend compounds. This was caused by the interaction between silica and ENR. In addition, it was confirmed that the increased wear resistance as the BR content increased. Furthermore, compared to the NR/BR blend compounds, ENR-25/BR blend compounds exhibited a lower tan 𝛿 value at 60℃ because silica was used as filler. This indicates a higher fuel efficiency. The measurement results for wear particulate matter showed that as increasing the BR content resulted in generation of less wear particulate matter. This was caused by the increased wear resistance. Moreover, the ENR-25/BR blend compounds with excellent filler-rubber interaction exhibited lower quantities of generated wear particulate matters as compared to the NR/BR blend compounds.

• Analytical Science and Technology
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• v.23 no.6
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• pp.579-586
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• 2010

Commercially widely used antitumor agents such as hydroxy urea, 6-mercaptopurine monohydrate, cytosine arabinoside, cyclophosphamide monohydrate and uracil were reacted with 3-(triethoxysilyl)propyl isocyanate and the product hydrolyzed to give silica nanoparticles bound antitumor agents ranging from 10 nm to micron-sized aggregates. The silyl isocyanate derivative was also reacted neat with water to give hybrid organicsilicananoparticles containing $-CH_2-CH_2-CH_2-NH-COOH$ or the corresponding decarboxylated propylamine groups depending on solvent and temperature employed. In vitro tests these functionalized silica nanoparticles were effective in the treatment of malignant tumor cells but had little or no effect on normal cells. Malignant human lung, ovarian, melanoma, CNS(Central nervous system) and colon tumor cells were used in this research. The use of silica as a carrier medium in the present research serves as a model material due to its ready functionalization via silation. The proof of concept established by the results suggests that the technique may be applied to other, more biocompatible carrier nanoparticles.

• Korean Journal of Pharmacognosy
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• v.34 no.4 s.135
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• pp.269-273
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• 2003

The leaves of Acanthopanax sessiliflorus Seem. (Araliaceae), which is native plant to Korea, have not been studied yet on triterpene constituents. Three 3,4-seco-lupane triterpenoids (Compound I-III) were isolated from the MeOH extract of this plant using Diaion HP-20P, silica gel and ODS column chromatographes. Based on physicochemical and spectroscopic data, the chemical structures of these compounds were identified as follows ; chiisanogenin (Compound I), chiisanoside (Compound II), $22{\alpha}-hydroxychiisanoside$ (Compound III).