• Polymer(Korea)
• /
• v.39 no.1
• /
• pp.165-168
• /
• 2015

Thermoresponsive polymers were successfully synthesized by a combination of atom transfer radical polymerization (ATRP) and Cu(I)-catalyzed 1,3-dipolar cycloaddition of azide and alkynes (click chemistry). Poly(2-hydroxyethyl methacrylate) (PHEMA) was synthesized by ATRP, followed by introduction of alkyne groups using pentynoic acid, leading to HEMA-alkyne. Homopolymers having secondary amine groups, tertiary amines with hydroxyethyl and hydroxypropyl groups were synthesized by adding 2-azido-N-ethyl-ethanamine, 2-[(2-azidoethyl)amino]ethanol, and 2-[(2-azidoethyl)amino]propanol, respectively, to the PHEMA-alkyne backbone using click chemistry. Molecular weight (MW), molecular weight distribution (MWD), and click reaction efficiency were determined by gel permeation chromatography (GPC) and $^1H$ NMR spectroscopy. The transmission spectra of the 1.0 wt% aqueous solutions of the resulting polymers at 650 nm were measured as a function of temperature. Results showed that the lower critical solution temperature (LCST) could be easily controlled by the length of the hydroxyalkyl groups.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.10
• /
• pp.1406-1410
• /
• 2003

The studies were based on the RAPD fingerprinting for the species identification of animals. The genomic DNA samples of ostriches, Taiwan local chickens, Aboracres broilers, Leghorn chickens, quails, doves, emus, Beltville small white turkeys, pheasants, Chinese geese, mule ducks, Holstein cattle and Landrace pigs were amplified with random primers by RAPD-PCR for fingerprinting. The results showed that the varied band patterns of DNA fingerprints were generated from templates depending on the kinds of primers or animal species. The same primer applied to the same breed, all of the main bands are similar, but which were different among species. In order to try to identify the species from the mixture of meat by RAPD fingerprinting, the meat of ostrich and cattle was mixed in different ratios for this study. The results showed that it could be easily and precisely distinguished according to the band distribution of RAPD patterns.

• Journal of Korea Foresty Energy
• /
• v.17 no.1
• /
• pp.30-35
• /
• 1998

The cellulose modification can be made in steps, giving a range of new products having properties quite different from the parent cellulose. Effective molecular weight control and narrow molecular weight distribution of the polyacrylonitrile can be accomplished by anionic polymerization technique. Preformed polyacrylonitrile was grafted precisely onto cellulose acetate by SN$_2$ reaction mechanism in a simple and effective way under homogeneous reaction condition. The 3.5g of completely dried cellulose acetate(DS=2.4) dissolved in 50ml of dry THF was transferred to the 215m1 polyacrylonitrile solution. The mixture was stirred vigorously under nitrogen atmosphere for 2 hrs. FTIR spectra of cellulose acetate and grafted cellulose acetate were taken, and their characteristic bands were identified.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.2
• /
• pp.453-456
• /
• 2010

The structural and energetic preferences of thiacalix[4]biscrown-5 with and without alkali metal ions ($Na^+$, $K^+$, $Rb^+$, and $Cs^+$) have been theoretically investigated for the first time using molecular dynamic (MD) simulations and density functional theory (MPWB1K/6-31G(d)//B3LYP/6-31G(d)) methods. The formation of the metal ion complex by the host is mainly driven by the electrostatic attraction between crown-5 oxygens and a cation together with the minor contribution of the cation-$\pi$ interaction between two facing phenyl rings around the cation. The computed binding energies and the atomic charge distribution analysis for the metal binding complexes indicate the selectivity toward a potassium ion. The theoretical results herein explain the experimentally observed extractability order by this host towards various alkali metal ions. The physical nature and the driving forces for cation recognition by this host are discussed in detail.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.9
• /
• pp.2694-2698
• /
• 2014

A multisegmented polystyrene (PS) with pH-cleavable ester and carbamate linkages was successfully synthesized by a combination of atom transfer radical polymerization (ATRP) and Cu(I)-catalyzed 1,3-dipolar cycloaddition of azide and alkynes (click chemistry). ATRP was employed to synthesize polystyrene from hydroxyl-terminated initiator using CuBr/N,N,N',N",N"-pentamethyldiethylenetriamine (PMDETA) as the catalyst. The reaction of the resulting PS with sodium azide yielded the azido-terminated polymer. The hydroxyl group in the other end of the polymer was reacted with 4-nitrophenyl chloroformate (NPC), followed by reaction with propargylamine to produce an alkyne end group with a carbamate linkage. The PS with an alkyne group in one end and an azide group in the other end was then self-coupled in the presence of CuBr/2,2'-bipyridyl (bpy) in DMF to yield a desired multisegmented PS. Molecular weight and molecular weight distribution of the self-coupled polymer increased with time, as in the typical step-growth-type polymerization processes. Finally, we demonstrated that the ester and carbamate linkages of the multisegmented PS were hydrolyzed in the presence of HCl to yield individual PS chains.

• Journal of Radiopharmaceuticals and Molecular Probes
• /
• v.3 no.2
• /
• pp.80-84
• /
• 2017

Re-188 is an excellent and practical radioisotope produced by W-188/Re-188-generator for therapy. We prepared Re-188-tin colloid for therapy of various diseases and tried to treat peritoneal effusion in animal model. Sarcoma-180 cells were injected into ICR mice to induce peritoneal effusion and the mice were grown for 3 d. Re-188-tin colloids (0.25, 0.5, and 1 mCi/mL per 30 g body weight) were injected into the mice and the mice were grown for 90 d. Planar gamma scintigraphy showed even distribution of Re-188-tin colloid radioactivity. Bax expression was found to be dose dependent to Re-188-tin colloid. Normal saline treated group showed the shortest survival time. Among the treated groups, 0.5 mCi dose group showed the longest survival time. In conclusion, Re-188-tin colloid was prepared successfully and showed the feasibility to use as a peritoneal effusion treatment in mice.

• ALGAE
• /
• v.29 no.4
• /
• pp.279-288
• /
• 2014

Red algal parasites are common within red algae and are mostly closely related to their hosts, but have a reduced habit. In the past, red algal parasites, due to their reduced morphology, have been given distinct generic names, even though they are often phylogenetically nested in their host's genus. This is a problem nomenclaturally for maintenance of a taxonomy based on monophyly. This study investigates the morphology, genetic variation and distribution of an undescribed red algal parasite growing on its host Rhodophyllis membranacea, widely distributed throughout New Zealand. Microscopy, molecular markers (plastid, mitochondrial, nuclear), and herbarium investigation were used to investigate this species. The parasite is widely distributed throughout New Zealand. All molecular markers clearly show that the parasite is almost identical to the host, even though morphologically quite distinct from members of the host genus. We believe that to maintain monophyly of Rhodophyllis the parasite should be described as a new species of Rhodophyllis, Rhodophyllis parasitica sp. nov. We also recommend that in order to maintain generic monophyly most red algal parasite genera should also be transferred to their host genus.

• Journal of The Korean Astronomical Society
• /
• v.27 no.1
• /
• pp.31-44
• /
• 1994

The 4.8GHz formaldehyde absorption line in the dark clouds in M17 and NGC 2024 regions has been mapped. In both nebulae, we detected two $H_2CO$ line components. In M17, the 24km $S^{-1}$ cloud is closely associated with the HII region located in front of the radio continuum source, and the 19km $S^{-1}$ cloud is associated with the visual dark clouds with a larger extent which are closer to us. The 19km $S^{-1}$ cloud has a mass motion approaching to the HII region. In both clouds, a velocity gradient from the north-east to the south-west directions is observed. The linewidth has no variation indicating no collapsing motion. In NGC 2024, the 9km $S^{-1}$ feature is extended along the dark bar in front of the bright nebula and a weak second component at 13km $S^{-1}$ is confined to the immediate vicinity of the radio source. Indications are that the 9km $S^{-1}$ cloud is physically associated with the dark bar and the 13km $S^{-1}$ cloud is located behind the radio source. The angular extent, the column density, and the total mass of the clouds are derived. The radial velocities of other molecular lines observed in these clouds are compared.

• Animal cells and systems
• /
• v.13 no.3
• /
• pp.297-304
• /
• 2009

A complete mRNA sequence of transferrin from the wax moth, Galleria mellonella, was obtained, and compared with those of other species. We previously reported that the sequence was most similar to those of Manduca sexta and Bombyx mori. As in other moths, G. mellonella transferrin had only one iron-binding site at its N-terminal region. Semi-qRT PCR was conducted to investigate tissue-specific distribution and transcriptional regulation of the wax moth transferrin mRNA. Larval muscle and fat body contained larger quantity of mRNA than other tested tissues. In this study, it was observed that iron and cadmium regulated transferrin transcription, and this regulation pattern was tissue specific. Iron up-regulated transferrin mRNA level in fat body, while suppressed it in the Malpighian tubules and silk glands. Cadmium decreased the mRNA level in fat body, muscle, and Malpighian tubules, but significantly increased the mRNA level in silk glands. In addition, the mRNA expression was induced by all tested pathogen-associated molecular patterns (PAMPs) including LPS, lipoteichoic acid (LTA), glucan, and even chitin.

• The Bulletin of The Korean Astronomical Society
• /
• v.40 no.2
• /
• pp.52.1-52.1
• /
• 2015

FIMS/SPEAR is a dual-channel far-ultraviolet imaging spectrograph on board the Korean microsatellite STSAT-1, which was launched on 2003 September 27. The primary mission goal of FIMS was to conduct a survey of diffuse far UV emissions in our Galaxy. For this purpose, FIMS completed a survey of about 84% of the sky during its operation of a year and a half. The present study aims to analyze this survey data made in the far UV wavelengths to understand the global evolution of our Galaxy. The far UV wavelength band is known to contain important cooling lines of hot gas: hence, the study will show how the hot gas in our Galaxy, produced by stellar winds and supernova explosion, evolves globally to cool down and become mixed with ambient cooler medium. One of the main findings from previous analyses of the FIMS data is that molecular hydrogen exists ubiquitously in our Galaxy. This discovery leads to another important scientific question: how is molecular hydrogen distributed in our Galaxy and how does it affect globally the evolution of our Galaxy as a cold component? Hence, the present study will cover both the hot and cold components of the ISM, which will also provide the opportunity to investigate the interactions between the two.