Jung J.,Korea University |
Jung J.,LG Household and Health Care Co. |
Kim C.,Korea University
Journal of the Korean Physical Society | Year: 2013
In this study, we performed experimental studies on the formation of stripe patterns in a granular mixture under horizontal vibration. The granular mixture was prepared by mixing brass and glass beads of 1 mm in diameter in the ratio of 1:2 by volume and immersing them in a liquid. The mixture becomes separated into glass-only and brass-only bands of random sizes. The number of bands is an increasing function of Γ × √Re only (Γ: acceleration relative to gravity; Re: Reynolds number based on the particle diameter). As the mechanism of stripe formation, the formation of clusters in the mixture due to local fluctuations and strong hydrodynamic interactions between particles is proposed. The initial-condition dependency also supports the cluster formation mechanism rather than the Kelvin-Helmholtz-like hydrodynamic instability. © 2013 The Korean Physical Society.
Hong L.-Y.,Chungnam National University |
Ryu S.-H.,LG Household and Health Care Co. |
Kim D.-P.,Chungnam National University
Journal of Nanoscience and Nanotechnology | Year: 2010
The microcellular SiCN ceramics with high porosity and high surface area were fabricated from polysilazane as a viscous SiCN ceramic precursor and expandable microspheres as a self-sacrificial template. The fabrication steps were composed of (1) forming of expandable microsphere compact, (2) infiltrating polysilazane into the compact, (3) foaming and curing, (4) pyrolysis in N 2 gas. The microcellular structures and properties of the obtained ceramic products depended on the foaming and curing conditions as well as the pyrolysis temperature. When foamed and cured at 120 °C for 30 min, then pyrolyzed at 1000 °C in N 2, the microcellular product exhibited the largest cell size 9.3 μm with the lowest cell densities 2.2 × 108 cells/cm 2, 93% of porosity and surface area of 356 m 2/g. Furthermore, the higher temperature pyrolysis at 1300 °C induced significant change in the microcellular morphology by reducing the cell size with thicker wall and the cell density. Finally, it demonstrated an efficient way of manufacturing highly porous microcellular ceramics with no etching process using a polyvinylsilazane and expandable microspheres for catalytic supporting application. Copyright © 2010 American Scientific Publishers.
Ryu J.H.,Dermaopro Ltd |
Seo Y.K.,Dermaopro Ltd |
Boo Y.C.,Kyungpook National University |
Chang M.Y.,LG Household and Health Care Co. |
And 2 more authors.
International Journal of Cosmetic Science | Year: 2014
Synopsis Objective Skin texture is a fine structure of skin surface where the hill and furrow were crossed to form a star shape. This study was performed to establish a quantitative evaluation method of skin texture affected by skin ageing using replica images of the cheek. Methods After producing replicas of the left cheek areas of 80 female subjects, representative replica images were chosen to establish six-level facial skin texture index. Using this new index, skin texture of different-aged subjects was visually assessed by multiple examiners. The number of star configurations was also analysed using the same replica images. Other factors contributing to skin texture, such as skin elasticity, roughness, dermal density, moisture and gloss, were also analysed. Results The concordance between skin texture scores evaluated by three researchers was high (0.896), and there was a high correlation between skin texture score and age (r = 0.642). The number of star configurations showed high correlations with skin texture scores (r = 0.753) and with age (r = 0.776). Skin texture scores were highly correlated with skin roughness and dermal density, but not with moisture, gloss and elasticity. Conclusion This study suggests that visual grading of skin texture score based on new facial skin texture index and quantification of star configurations will be useful in evaluating skin ageing. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.
Lee S.J.,Korea Research Institute of Chemical Technology |
Jung T.-H.,Korea Research Institute of Chemical Technology |
Kim H.,LG Household and Health Care Co. |
Jeong D.,Korea Research Institute of Chemical Technology |
And 5 more authors.
Archives of Pharmacal Research | Year: 2014
The interaction of stem cell factor (SCF) with its cognate receptor c-Kit is closely associated with the survival and maturation of melanocytes. To investigate novel depigmentation agents, we screened 2,000 plant extracts for c-Kit inhibitors to identify active small molecules by using time-resolved fluorescence enzyme assays. For the active extracts identified as inhibitors of c-Kit enzyme, we evaluated the effects of the active extracts and isolated flavonoids on c-Kit phosphorylation in MO7e/melanocytes. Anti-melanogenic activity was also examined in melanocytes and melanoderm model. The flavonoids such as diosmetin, apigenin, acacetin and luteolin isolated from Chrysanthemum morifolium were found to be active in inhibiting c-Kit both at enzyme and cellular levels. In addition, these flavonoids attenuated SCF-induced proliferation of human primary melanocytes without toxicity and suppressed ultraviolet (UV) B irradiation-mediated melanin synthesis significantly. Among the active flavonoids, diosmetin was found to inhibit SCF-induced melanogenesis in a human melanoderm model. These results strongly suggest that C. morifolium extract and diosmetin have potential to suppress SCF-/UVB-induced melanogenesis, and could be developed as anti-pigmentation agents. © 2013 The Author(s).
Yogiara,Yonsei University |
Yogiara,Atma Jaya Catholic University of Indonesia |
Hwang S.J.,LG Household and Health Care Co. |
Park S.,LG Household and Health Care Co. |
And 2 more authors.
Letters in Applied Microbiology | Year: 2015
Preservative agents determining the shelf life of cosmetic products must have effective antimicrobial activity while meeting safety requirements for topical use. In this study, we determined the antimicrobial activity of 1,2-hexanediol against several Gram-positive and Gram-negative bacteria. Antimicrobial susceptibility tests have shown that 1,2-hexanediol exhibits broad-spectrum activity against Gram-positive and Gram-negative bacteria with MICs of 0·5-2% (v/v). The bactericidal concentration of 1,2-hexanediol was ranging from 1 to 2 × MIC as demonstrated by time-kill curve assay. A membrane depolarization assay showed that 1,2-hexanediol disrupted the cytoplasmic membrane potential. A checkerboard assay indicated that the effective concentration of 1,2-hexanediol was reduced up to 0·25-0·5 × MIC when combined with macelignan and octyl gallate against Gram-positive bacteria. However, this combination was not effective against Gram-negative bacteria. A turbidity reduction assay demonstrated that the combination of a high concentration of 1,2-hexanediol with food-grade antimicrobial compounds could trigger lytic activity towards Bacillus cereus cells. The remaining cell turbidity was 24·6 and 22·2% when 2% of 1,2-hexanediol was combined with 8 mg l-1 octyl gallate or with 32 mg l-1 macelignan respectively. This study showed that food-grade antimicrobial compounds may be used in combination with 1,2-hexanediol to increase its efficacy as a preservative agent in cosmetics. Significance and Impact of the Study: The antimicrobial activity of 1,2-hexanediol against Gram-positive and Gram-negative bacteria was potentiated with food-grade antimicrobials including xanthorrhizol, macelignan, panduratin A and octyl gallate, which have already been reported to display anti-inflammatory and other beneficial activities related to cosmetics. Therefore, the combination of 1,2-hexanediol and these food-grade antimicrobial agents would have benefits not only for increasing the antimicrobial activity but also in cosmetics use. Significance and Impact of the Study: The antimicrobial activity of 1,2-hexanediol against Gram-positive and Gram-negative bacteria was potentiated with food-grade antimicrobials including xanthorrhizol, macelignan, panduratin A and octyl gallate, which have already been reported to display anti-inflammatory and other beneficial activities related to cosmetics. Therefore, the combination of 1,2-hexanediol and these food-grade antimicrobial agents would have benefits not only for increasing the antimicrobial activity but also in cosmetics use. © 2015 The Society for Applied Microbiology.