Kang C.,Daegu Regional Environmental Office |
Ashurst R.W.,Auburn University |
Shim J.-J.,Yeungnam University |
Huh Y.S.,Inha University |
Roh C.,Korea Atomic Energy Research Institute
Bioprocess and Biosystems Engineering | Year: 2014
Here, we present a simple method for controlling the density of Au nanoparticles (Au NPs) on a modified silicon substrate, by destabilizing the colloidal Au NPs with 3-mercaptopropyltrimethoxylsilane (3-MPTMS) for microelectromechanical-system-based applications to reduce tribological issues. A silicon surface was pretreated with a 3-MPTMS solution, immediately after which thiolated Au NPs were added to it, resulting in their uniform deposition on the silicon substrate. Without any material property change of the colloidal Au NPs, we observed the formation of large clusters Au NPs on the modified silicon surface. Analysis by scanning electron microscopy with energy dispersive X-ray spectroscopy indicated that the addition of 3-MPTMS resulted in an alternation of the chemical characteristics of the solution. Atomic force microscopy imaging supported the notion that silicon surface modification is the most important factor on tribological properties of materials along with ligand-modified Au NPs. The density of Au NPs on a silicon surface was significantly dependent on several factors, including the concentration of colloidal Au NPs, deposition time, and concentration of 3-MPTMS solution, while temperature range which was used throughout experiment was determined to have no significant effect. A relatively high density of Au NPs forms on the silicon surface as the concentrations of Au NPs and 3-MPTMS are increased. In addition, the maximum deposition of Au NPs on silicon wafer was observed at 3 h, while the effects of temperature variation were minimal. © 2014 Springer-Verlag.
Roh C.,Korea Atomic Energy Research Institute |
Lee S.J.,Chonnam National University |
Nasir Uddin S.M.,Korea Atomic Energy Research Institute |
Kim J.K.,Korea Atomic Energy Research Institute |
Kang C.K.,Daegu Regional Environmental Office
European Food Research and Technology | Year: 2015
Obesity is the fifth leading cause of death globally. At least 2.8 million adults die each year as a result of being overweight. Therefore, the development of an efficient lipid inhibitor for the biological effects of obesity is highly needed. The discovery of bioactive compounds from food is one possible way to control obesity and to prevent or reduce the risks of various obesity-related diseases. In this study, we found that 7,3′,4′-trihydroxyisoflavone from Korean soybean paste has remarkable anti-obesity activity in vitro and in vivo. Treatment with 7,3′,4′-trihydroxyisoflavone significantly reduced the adipose tissue weight to 1.6/100 g of body weight in high-fat mice. In addition, in 7,3′,4′-trihydroxyisoflavone-treated mice, a significant reduction in the serum triglyceride and T-cholesterol was observed at 29 and 37 %, respectively. These results support the hypothesis that 7,3′,4′-trihydroxyisoflavone is expected to create a therapeutic interest in its use for the treatment of obesity. © 2014, Springer-Verlag Berlin Heidelberg.
Pham Q.L.,Yeungnam University |
Haldorai Y.,Yeungnam University |
Nguyen V.H.,Yeungnam University |
Nguyen V.H.,Nha Trang University |
And 2 more authors.
Korean Journal of Chemical Engineering | Year: 2014
Two highly supercritical CO2-soluble, poly(vinyl acetate) (PVAc)-based macro-reversible addition-fragmentation chain transfer (RAFT) agents were synthesized. The RAFT agents were used for the first time in RAFT/macromolecular design via the interchange of xanthates (MADIX) and polymerization of vinyl acetate (VAc) and vinyl pivalate (VPi) in supercritical carbon dioxide (scCO2). A homopolymer PVAc and a block copolymer PVAc-b-PVPi made by RAFT/MADIX polymerization were characterized, and the effects of time and RAFT agents on polymerization were examined. For the 8.4 wt% RAFT agent in VAc, the molecular mass (Mn) of homopolymer PVAc was 26,000 g mol−1and PDI was 1.35. For the copolymerization of VPi using 9.8 wt% PVAc-RAFT agent in VPi for 24 h, the Mnand PDI of PVAc-b-PVPi reached 32,400 g mol−1and 1.42, respectively. These results suggest that the polydispersity can be controlled during the clean production of PVAc and PVPi by RAFT/MADIX polymerization in scCO2. © 2014, Korean Institute of Chemical Engineers, Seoul, Korea.
Park H.-C.,Seoul National University |
Han T.-Y.,Daegu Munhwa Broadcasting Corperation |
Kim D.-C.,Daegu Regional Environmental Office |
Min M.-S.,Seoul National University |
And 3 more authors.
Genes and Genomics | Year: 2011
The Eurasian otter, Lutra lutra, is a well known endangered species in South Korea that experienced rapid population decreases through poaching and industrialization until the 1980's. To evaluate the genetic diversity and the existing number of otters recently found in Daegu City, 81 fecal samples collected from the Gumho River and Shincheon stream were subjected to DNA extraction for sex determination and genetic analysis using nuclear genetic markers. Individual identification and relatedness between individuals were detemined by genotypic data using twelve microsatellite loci, and sex identification was also determined based on sequence variation of the zinc finger protein gene on sex chromosomes. Our results showed that at least seven otter individuals were identified and the kinship relationships of seven individual pairs were determined. It was concluded that otters distributed widely in Daegu City have moderate levels of genetic diversity, and close monitoring of the small-sized otter population is necessary to promote successful settlement of the otters in the area. © The Genetics Society of Korea and Springer 2011.