• Polymer(Korea)
• /
• v.35 no.4
• /
• pp.308-313
• /
• 2011

The ring-opening isomerization polymerization behavior of 2,5,6,7-tetrahydro-3H-imidazo[2,1-b] [1,3] oxazine(TII) has been studied under various conditions. The present study aimed at improving the low polymerizability of the above monomer (six-membered ring) up to a level comparable to that of 2,5,6-tetrahydroimidazo[2,1-b] [l,3] oxazole(TIO) (five-membered ring). The optimum result could be observed when methyl trifluoromethanesulfonate(MeOTf) and nitrobenzene were used as an initiator and a solvent in the polymerization at $60^{\circ}C$ for 24 h. Polymers were confirmed by$^1H$ NMR과$^{13}C$ NMR, and m measurements. The molecular weight obtained by gel permeation chromatography (GPC) corresponded to the molecular weight theoretically calculated from the feed ratio. The melting temperature ($T_m$) of TII was conspicuously different from that of TIO, because of the difference in the alkyl group.

• Macromolecular Research
• /
• v.16 no.6
• /
• pp.510-516
• /
• 2008

New antitumor active polymers, poly(methacryloyl-2-oxy-1,2,3-propanetricarboxylic acid-co-exo-3,6-epoxy-l,2,3,6-tetrahydrophthalic acid) [poly(MTCA-co-ETAc)], poly(methacryloyl-2-oxy-l,2,3-propanetricarboxylic acid-co-hydrogen ethyl-exo-3,6-epoxy-l,2,3,6-tetrahydrophthalate) [poly(MTCA-co-HEET)], and poly(methacryloyl-2-oxy-l,2,3-propanetricarboxylic acid-co-a-ethoxy-exo-3,6-epoxy-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil) [poly(MTCA-co-EETFU)] were synthesized and characterized. Their antitumor activity, inhibition of DNA replication and antiangiogenesis were examined. The structures of the polymers were identified by FT-IR, $^1H$ and $^{13}C$-NMR spectroscopy. The number average molecular weights of the fractionated polymers determined by GPC ranged from 9,400 to 14,900, and polydispersity indices were less than 1.7. The in vitro cytotoxicity of these polymers was determined and their antitumor activity was evaluated. The $IC_{50}$ values (the drug concentration at inhibition of 50% tumor growth) indicated that the synthesized polymers were much better inhibitors of cancer cells and showed lower cytotoxicity than the free 5-FU. The in vivo antitumor activity of the conjugates was examined using mice bearing the sarcoma 180 tumor cell line. The life spans (TIC) of the mice treated with the conjugates were higher than those treated with the free 5-FU. In addition, the synthesized conjugates showed excellent antiangiogenic activity based on an embryo chorioallantoic membrane assay.

• Advances in materials Research
• /
• v.2 no.4
• /
• pp.209-219
• /
• 2013

We have described primary studies on conductivity and molecular weight of polyaniline separately in the electric and magnetic fields when it is used in a field effect experimental configuration. We report further studies on doped in-situ deposited polyaniline. First we have chemically synthesized polyaniline by ammonium peroxodisulfate in acidic aques and organic solutions at different times. Then we measured mass and conductivity and obtained the best time of polymerizations. In continue, we repeated these reactions separately under different electric and magnetic fields in constant time and measured mass and conductivity. The polyaniline is characterized by gel permeation chromatography (GPC), UV-Visible spectroscopy and electrical conductivity. High molecular weight polyanilines are synthesized under electric field, $M_w$ = 520000-680000 g/mol, with $M_w/M_n$ = 2-2.5. The UV-Visible spectra of polyanilines oxidized by ammonium peroxodisulfate and protonated with dodecylbenzenesulfonic acid (PANi-DBSA), in N-methylpyrolidone (NMP), show a smeared polaron peak shifted into the visible. Electrical conductivity of polyanilines has been studied by four-probe method. The conductivity of the films of emeraldine protonated by DBSA cast from NMP are higher than 500 and 25 S/cm under 10 KV/m of potential) electric field and 0.1 T magnetic field, respectively. It shows an enhanced resistance to ageing too. By the next steps, we carried chemical polymerization at the best electric and magnetic fields at different times. Finally, resulted in finding the best time and amount of the fields. The longer polymerization time and the higher magnetic field can lead to degradation of polyaniline films and decrease conductivity and molecular mass.

• Journal of Adhesion and Interface
• /
• v.1 no.1
• /
• pp.15-22
• /
• 2000

To prepare acrylic type pressure-sensitive adhesive, quarter polymers were synthesized from butylacrylate (BA), 2-ethylhexylacrylate (2-EHA), methyl methacrylate (MMA), 2-hydroxyethylmethacrylate (2-HEMA). The quarter polymer was identified by FT-IR. Molecular weight was measured by Gel Pearmeation Chromatograhy. Also, viscosity, solid content and peel strength were investigated. The peel strength was $160g_f/25mm$ when the volume ratio of feed monomer to solvent was 1.3:1 and the ratio was relevant to commercial usage. The pot life of adhesive was 30 s at the 50 m/min of heat treatment rate, and it indicated that the minimum drying time was 30 s. Not only weathering resistance keep up peel strength $160{\sim}180g_f/25mm$ after 1000 h, but also no residual remains.

• Polymer(Korea)
• /
• v.38 no.1
• /
• pp.85-92
• /
• 2014

To develop water-soluble chitosan as an effient gene delivery carrier, chitosan oligosaccharides (COSs) with various molecular weights (MW) were studied for gene transfection agents. MWs of COSs fractionated by ultrafiltration techniques were identified as narrow MW distributions with the average MW ranging from 1 to 10 kDa through gel permeation chromatography (GPC) measurement depending on the applied ultrafiltration membranes. Their structural characterizations were analyzed by FTIR spectrophotometer and $^1H$ NMR. The degree of deacetylation was determined by UV spectroscopy showing the degree of deacetylation above 90%. The relative cell viabilities were maintained over 100% (10 mg/mL), independent of the MW of the fractionated COSs. The fractionated COSs of 10 mg/mL concentration with narrow MW distributions showed non-cytotoxicity in Caco-2 cells.

• The Bulletin of The Korean Astronomical Society
• /
• v.46 no.2
• /
• pp.45.1-45.1
• /
• 2021

Horizon Run 5 (HR5) is a cosmological hydrodynamical simulation which captures the properties of the Universe on aGpc scale while achieving a resolution of 1kpc. This enormous dynamic range allows us to simultaneously capture the physics of the cosmic web on very large scales and account for the formation and evolution of dwarf galaxies on much smaller scales. On the back of a remarkable achievement of this, we have finished to run follow-up simulations which have 2 times larger volume than before and are expected to complementary to some limitations of previous HR simulations both for the study on the large scale features and the expansion history in a distant Universe. For these simulations, we consider the sub-grid physics of radiative heating/cooling, reionization, star formation, SN/AGN feedbacks, chemical evolution and the growth of super-massive blackholes. In order to do this project, we implemented a hybrid MPI-OpenMP version of the RAMSES code, 'RAMSES-OMP', which is specifically designed for modern many-core many thread parallel systems. These simulation successfully reproduce various observation result and provide a large amount of statistical samples of Lyman-alpha emitters and protoclusters which are important to understand the formation and expansion history of early universe. These are invaluable assets for the interpretation of current ΛCDM cosmology and current/upcoming deep surveys of the Universe, such as the world largest narrow band imaging survey, ODIN (One-hundred-square-degree Dark energy camera Imaging in Narrow band).

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.2
• /
• pp.55.3-55.3
• /
• 2019

We present a pipeline to estimate baryonic properties of a galaxy inside a dark matter (DM) halo in DM-only simulations using a machine trained on high-resolution hydrodynamic simulations. As an example, we use the IllustrisTNG hydrodynamic simulation of a (75 h^-1 Mpc)³ volume to train our machine to predict e.g., stellar mass and star formation rate in a galaxy-sized halo based purely on its DM content. An extremely randomized tree (ERT) algorithm is used together with multiple novel improvements we introduce here such as a refined error function in machine training and two-stage learning. Aided by these improvements, our model demonstrates a significantly increased accuracy in predicting baryonic properties compared to prior attempts --- in other words, the machine better mimics IllustrisTNG's galaxy-halo correlation. By applying our machine to the MultiDark-Planck DM-only simulation of a large (1 h^-1 Gpc)³ volume, we then validate the pipeline that rapidly generates a galaxy catalogue from a DM halo catalogue using the correlations the machine found in IllustrisTNG. We also compare our galaxy catalogue with the ones produced by popular semi-analytic models (SAMs). Our so-called machine-assisted semi-simulation model (MSSM) is shown to be largely compatible with SAMs, and may become a promising method to transplant the baryon physics of galaxy-scale hydrodynamic calculations onto a larger-volume DM-only run. We discuss the benefits that machine-based approaches like this entail, as well as suggestions to raise the scientific potential of such approaches.

• The Bulletin of The Korean Astronomical Society
• /
• v.45 no.1
• /
• pp.38.2-38.2
• /
• 2020

Horizon Run 5 (HR5) is a cosmological hydrodynamical simulation which captures the properties of the Universe on a Gpc scale while achieving a resolution of 1 kpc. This enormous dynamic range allows us to simultaneously capture the physics of the cosmic web on very large scales and account for the formation and evolution of dwarf galaxies on much smaller scales. Inside the simulation box. we zoom-in on a high-resolution cuboid region with a volume of 1049 × 114 × 114 Mpc3. The subgrid physics chosen to model galaxy formation includes radiative heating/cooling, reionization, star formation, supernova feedback, chemical evolution tracking the enrichment of oxygen and iron, the growth of supermassive black holes and feedback from active galactic nuclei (AGN) in the form of a dual jet-heating mode. For this simulation we implemented a hybrid MPI-OpenMP version of the RAMSES code, specifically targeted for modern many-core many thread parallel architectures. For the post-processing, we extended the Friends-of-Friend (FoF) algorithm and developed a new galaxy finder to analyse the large outputs of HR5. The simulation successfully reproduces many observations, such as the cosmic star formation history, connectivity of galaxy distribution and stellar mass functions. The simulation also indicates that hydrodynamical effects on small scales impact galaxy clustering up to very large scales near and beyond the baryonic acoustic oscillation (BAO) scale. Hence, caution should be taken when using that scale as a cosmic standard ruler: one needs to carefully understand the corresponding biases. The simulation is expected to be an invaluable asset for the interpretation of upcoming deep surveys of the Universe.

• Progress in Medical Physics
• /
• v.21 no.1
• /
• pp.35-41
• /
• 2010

The purpose of this study is to quantitate regional neurochemical profile of regional normal adult mice brain and assess regional metabolic differences by using ex vivo $^1H$ high-resolution magic angle spinning nuclear magnetic resonance spectroscopy ($^1H$ HR-MAS NMRS). The animals were matched in sex and age. The collected brain tissue included frontal cortex, temporal cortex, thalamus, and hippocampus. Quantitative 1D spectra were acquired on 40 samples with the CPMG pulse sequence (8 kHz spectral window, TR/TE = 5500/2.2 ms, NEX = 128, scan time: 17 min 20 sec). The mass of brain tissue and $D_2O$+TSP solvent were 8~14 mg and 7~13 mg. A total of 16 metabolites were quantified as follow: Acet, NAA, NAAG, tCr, Cr, tCho, Cho, GPC + PC, mIns, Lac, GABA, Glu, Gln, Tau and Ala. As a results, Acet, Cho, NAA, NAAG and mIns were showed significantly different aspects on frontal cortex, hippocampus, temporal cortex and thalamus respectively. The present study demonstrated that absolute metabolite concentrations were significantly different among four brain regions of adult mice. Our finding might be helpful to investigate brain metabolism of neuro-disease in animal model.

• Applied Chemistry for Engineering
• /
• v.29 no.4
• /
• pp.461-467
• /
• 2018

In this study, $(n-BuCp)_2ZrCl_2$, was supported on $SiO_2/MgCl_2$ binary support. Before supporting the catalyst, the $SiO_2/MgCl_2$ binary support was surface treated with three different alkyl aluminum compound, namely trimethylaluminum, triethylaluminum, and ethylaluminum sesquichloride. The synthesized surface-treated $SiO_2/MgCl_2$ supported metallocene catalysts were used for the copolymerization of ethylene and 1-hexene. Their catalytic properties and performances were analyzed through BET, XPS analysis, ICP-AES analysis, and FE-SEM. While the resulting copolymers were analyzed through DSC analysis, GPC analysis, 13C-NMR analysis, and FE-SEM. The analysis of synthesized surface-treated $SiO_2/MgCl_2$ supported metallocene catalysts showed that the Zr content of these catalysts is relatively lower compared to that of the catalyst supported on $SiO_2$. This could be attributed to the reduction in the surface area of $SiO_2$ due to the presence of recrystallized $MgCl_2$ and alkyl aluminum. Furthermore, they exhibited a better copolymerization activity compared to that of $SiO_2$ supported catalyst, particularly the EASC-surface treated binary support, which has the highest activity of 1.9 kg PE/($mmol-Zr^*hr$) because EASC acts as a strong Lewis acid. It could also be observed that the larger the ligand of alkyl aluminum used, the rougher the particle surface of the resulting polymer.