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Mechanical Properties of Thermoplastic Composite Reinforced Porous Carbon
Hwang, Taek-Sung,Park, Jin-Won,Song, Hae-Young,Hwang, Eui-Hwan 한국탄소학회 2000 Carbon Letters Vol.1 No.2
Porous carbon from charcoal filled polypropylene composites were prepared and their mechanical properties were evaluated. In preparing the composites, crosslinking agent (sodium benzonate) were used in order to improve the bonding force between matrix and fillers. In this study, the effects of charcoal powder and sodium benzonate concentration on the mechanical properties and interface phenomena on the composites were evaluated. The mechanical properties of composites increased progressively with the decrease of filler loading. In the case of addition of the crosslinking agent into the composite, the mechanical properties were increased and showed maximum value at the 3 wt% concentration of sodium benzonate. According to the result of the TGA, the weight loss of composite according to crosslinking agent was not observed and initial thermal degradation temperature of composite reinforced charcoal was located at $390^{\circ}C$.
Titanium Oxide Layer with Micro and Nano Tubes on Titanium Substrate
Hwang, Jae Sun,Lee, Sang Bae,Oh, Keun Taek,Kim, Kyoung Nam,Kim, Kwang Mahn Trans Tech Publications, Ltd. 2006 Key Engineering Materials Vol.309 No.-
<P>The formation of titanium oxide layer with micro and nanotube arrays on titanium substrate was investigated by grit-blasting and anodic oxidation treatment. Micro rough surface can be formed by grit-blasting and nanotube arrays can be formed by anodic oxidation. The morphology of the hybrid surface(micro and nanotube arrays surface) can be affected by the mechanical conditions (grit size, grit material, blasting pressure, nozzle tip of blasting machine, distance nozzle tip and specimen, blasting time) and electrochemical conditions (applied potential, electrolyte concentration and anodizing time) used. Such micro pore and nanotube arrays of titanium oxide can be useful for well-adhered bioactive surface layer on Ti implant metals for orthopedic and dental implants, as well as for photo catalysts and other sensor applications.</P>
Hwang, Eunson,Park, Sang-Yong,Yin, Chang Shik,Kim, Hee-Taek,Kim, Yong Min,Yi, Tae Hoo The Korean Society of Ginseng 2017 Journal of Ginseng Research Vol.41 No.1
Background: Human skin undergoes distinct changes throughout the aging process, based on both intrinsic and extrinsic factors. In a process called photoaging, UVB irradiation leads to upregulation of matrix metalloproteinase-1, which then causes collagen degradation and premature aging. Mixtures of medicinal plants have traditionally been used as drugs in oriental medicine. Based on the previously reported antioxidant properties of Panax ginseng Meyer and Crataegus pinnatifida, we hypothesized that the mixture of P. ginseng Meyer and C. pinnatifida (GC) would have protective effects against skin aging. Methods: Anti-aging activity was examined both in human dermal fibroblasts under UVB irradiation by using Western blot analysis and in healthy human skin by examining noninvasive measurements. Results: In vitro studies showed that GC improved procollagen type I expression and diminished matrix metalloproteinase-1 secretion. Based on noninvasive measurements, skin roughness values, including total roughness (R1), maximum roughness (R2), smoothness depth and average roughness (R3), and global photodamage scores were improved by GC application. Moreover, GC ameliorated the high values of smoothness depth (R4), which means that GC reduced loss of skin moisture. Conclusion: These results suggest that GC can prevent aging by inhibiting wrinkle formation and increasing moisture in the human skin.
Sung Han Jung,Jeong Ho Hwang,Sang Eun. Kim,Hoon Taek Lee 한국동물번식학회 2012 Reproductive & Developmental Biology(Supplement) Vol.36 No.2s
Hyperacture rejection (HAR) of pig organs, upon xenotransplantation into primates, could partly be overcome by knocking out the alpha-Gal gene. However, xenotransplanted organs may still undergo immunological acture rejection (AR) or acute vascular rejection (AVR). Among several genes involved in AR and AVR, the hCD47 evades the monocyte/ macrophage mediated phagocytosis by identifying the self/non-self signal (CD47-SIRPa) whereas hTFPI participates in the regulation of coagulation pathway by acting upstream of the thrombin. In this study, we investigated hCD47 and hTFPI as two possible candidates for avoiding AR and AVR, respectively upon pig-to-human xenotransplantation. A co-expression vector for hCD47 and hTFPI was constructed using 2A peptides system (F2A) and transfected into the porcine kidney cell line (PK-15). The transfected cells stably expressed both hCD47 and hTFPI mRNA and proteins. Co-culture of non-transfected, hCD47-transfected, hTFPI-transfected or hCD47+hTPFI-transfected PK15 cells with natural killer (NK) cells, monocytes and macrophages confirmed the cytotoxic effect of hCD47 and revealed a synergistic effect of hCD47 and hTFPI co-transfection. There was an attractive survivability of 25~30% on each type of innate immune cell, NK cell and macrophage. These results suggest that transgenic pigs, genetically modified for hCD47 and hTFPI may be useful for overcoming xenograft rejection. Furthermore, cotransfection with hTFPI may enhance the cytotoxic effect of hCD47, possibly by assisting the hCD47-SIRPa binding by an unknown mechanism.