• Polymer(Korea)
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• v.26 no.6
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• pp.710-717
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• 2002

Molecularly imprinted polymers were prepared in particle forms by crosslinking methacrylic acid (MAA)) using all trans-retinoic acid as a template. The HPLC column packed with the prepared molecular imprinted polymers showed high capability in separation of retinoid derivatives. The column capacity factor and selectivity increased with increasing MAA to template ratio when the incorporated template amount was fixed, as it statistically generated more binding sites between host molecules and template. Molecularly imprinted polymer particles prepared via an emulsion polymerization method were round-shaped and their sizes were more uniformly distributed, but their separation capability was inferior to those obtained by solution polymerization method. It was presumably because the loss of interaction strength between MAA and the template due to hydrogen bonding either between MAA and water or between template and water during the synthesis of molecularly imprinted polymers.

• Polymer(Korea)
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• v.33 no.3
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• pp.263-267
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• 2009

In order to improve the hydrophilic property on the surface of d-PMMA(deuterated poly-(methyl methacrylate)) film, it was exposed to oxygen plasma, All experimental conditions were same except to plasma exposure time that was varied from 0 to 180 s, The effects according to the exposure time were identified using contact angles, X-ray reflectometer(XRR), neutron reflectometer(NR), and X-ray photoelectron spectroscopy(XPS). By confirming that as the exposure time increases, water contact angle decreases while the composition of oxygen increases, it was confirmed that the composition of oxygen has a huge influence on improving the hydrophilic property. The physical characters as a function of the exposure time were investigated by the XRR. By analyzing complementally the results of the XRR, NR, and XPS, more detailed chemical bonding conditions were studied by obtaining not only composition of the carbon and oxygen but that of the hydrogen.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.7-11
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• 2001

The influence of temperature and calcium concentration on the gelation kinetics of purified Aigeok system has been investigated by small deformation oscillatory measurement. DE(degree of esterification) of the present sample was indicated of low methoxyl Aigeok polysaccharide by FT-IR. The calcium induced gelation of Aigeok has been studied. Both moduli reached the saturation value during the period of experiments. Rate constant increased with increasing calcium concentration, however above 4.08 mM calcium chloride caused a sudden drop in gel strength. The experimental result that the decrease in gel strength at high calcium concentration was seems to be phase separation or competitive inhibition between calcium ions. The storage and loss shear moduli decreased with increasing temperature. The rate constant of Aigeok system remarkably dropped above $35^{\circ}C$. Thus hydrogen bonding is prior to hydrophobic interaction for Aigeok molecule.

• Journal of the Korean Chemical Society
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• v.30 no.6
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• pp.510-515
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• 1986

Spectra for the $v_3$+ Amide II combination band of thioacetamide(TA) were obtained in carbon tetrachloride solutions and in very dilute solutions of TA-N,N-dimethlylacetamide (DMA) in carbon tetrachloride in the range of 5~55$^{\circ}$C. The combination band in the three component system can be resolved into components due to monomeric TA, 1 : 1 TA-DMA complex and 1 : 2 TA-DMA complex. In the dilute solutions the experimental spectrum was resolved by using the computer into its two Lorentzian-Gaussian product components which have been identified with the monomeric TA and the 1 : 1 complex. The equilibrium constants and thermodynamic parameters of 1 : 1 complex were determined by analysis of concentration and temperature dependent spectra. The ${\Delta}H^{\circ}$ and ${\Delta}S^{\circ}$ for the 1 : 1 complex were -14.4 KJ mol$^{-1}$ and -15.6 J mol$^{-1}deg^{-1}$, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.5
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• pp.653-658
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• 2017

To evaluate the effects of amylose content and dissolution media on the molecular structure of maize starch, changes in the hydrodynamic diameter of starch molecules were assessed via dynamic light scattering depending on amylose content and dissolution media. As the amylose content of starch increased, the hydrodynamic diameter of starch molecules proportionally decreased from 204 to 92 nm. To alter ionic strength, hydrogen bonding, or polarity of dissolution media, various contents of NaCl (1, 2, or 3 M), urea (1, 2, or 3 M), or 1-butanol (0.1, 0.5, or 1.0%) were added to media, respectively, resulting in increased hydrodynamic diameter of starch. However, the degree of expansion was dependent on amylose content and the concentration and/or type of additive. The hydrodynamic diameter of starch molecules exhibited significant correlation with amylose content obtained by size exclusion chromatography, regardless of dissolution conditions.

• Genomics & Informatics
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• v.14 no.3
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• pp.112-124
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• 2016

Solid tumor is generally observed in tissues of epithelial or endothelial cells of lung, breast, prostate, pancreases, colorectal, stomach, and bladder, where several genes transcription is regulated by the microRNAs (miRNAs). Argonaute (AGO) protein is a family of protein which assists in miRNAs to bind with mRNAs of the target genes. Hence, study of the binding mechanism between AGO protein and miRNAs, and also with miRNAs-mRNAs duplex is crucial for understanding the RNA silencing mechanism. In the current work, 64 genes and 23 miRNAs have been selected from literatures, whose deregulation is well established in seven types of solid cancer like lung, breast, prostate, pancreases, colorectal, stomach, and bladder cancer. In silico study reveals, miRNAs namely, miR-106a, miR-21, and miR-29b-2 have a strong binding affinity towards PTEN, TGFBR2, and VEGFA genes, respectively, suggested as important factors in RNA silencing mechanism. Furthermore, interaction between AGO protein (PDB ID-3F73, chain A) with selected miRNAs and with miRNAs-mRNAs duplex were studied computationally to understand their binding at molecular level. The residual interaction and hydrogen bonding are inspected in Discovery Studio 3.5 suites. The current investigation throws light on understanding miRNAs based gene silencing mechanism in solid cancer.

• Bulletin of the Korean Chemical Society
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• v.26 no.6
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• pp.892-898
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• 2005

A long, bis(monodentate), linking Schiff-base ligand L (py-CH=N-$C_6H_4$-N=CH-py) was prepared from 1,4-phenylenediamine and 3-pyridinecarboxaldehyde by the Schiff-base condensation. Ligand L has two terminal pyridyl groups capable of coordinating to metals through their nitrogen atoms. In contrast, the same reaction between 1,2-phenylenediamine and 3-pyridinecarboxaldehyde produced a mixture of imidazol isomers (2-pyridin-3-yl-1H-benzoimidazole), which are connected to one another by the N-H…N hydrogen bonding to form a tetramer. From Zn($NO_3)_2{\cdot}6H_2O$ and ligand L under various conditions, one discrete molecule, trans- [Zn($H_2O)_4L_2]{\cdot}(NO_3)_2{\cdot}(MeOH)_2$, and two 1-D zinc polymers, [Zn$(NO_3)(H_2O)_2(L)]{\cdot}(NO_3){\cdot}(H_2O)_2$ and [Zn(L) (OBC)($H_2O$)], were prepared. In ligand L, the N$\ldots$N separation between the terminal pyridyl groups is 13.994 $\AA$, with their nitrogen atoms at the meta positions (3,3’) in a trans manner. The corresponding N$\ldots$N separations in its compounds range from 13.853 to 14.754 $\AA$.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.823-828
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• 2004

The crystal structures of sparteinium tetrachlorocuprate monohydrate $[(C_{15}H_{28}N_2)CuCl_4{\cdot}H_2O]$, 1 and sparteinium tetrabromocuprate monohydrate $[(C_{15}H_{28}N_2)CBr_4{\cdot}H_2O]$, 2, were determined. The structures of 1 [orthorhombic, $P2_12_12_1$, a = 8.3080(10) ${\AA}$, b = 14.6797(19) ${\AA}$ and c = 16.4731(17) ${\AA}$], and 2 [orthorhombic, $P2_12_12_1$, a = 8.4769(7) ${\AA}$, b = 15.166(3) ${\AA}$ and c = 16.679(3) ${\AA}$], are composed of a doubly protonated sparteinium cation, $[C_{15}H_{28}N_2]^{2+}$, a discrete $CuX_4^{2-}$ anion $(X=Cl^-\;or\;Br^-)$, and one water molecule. These monomeric compounds are stabilized through various types of hydrogen bonding interaction in their packing structures. Crystal 2 exhibits weak anti-ferromagnetism (J = -3.24 $cm^{-1}$) as opposed to the magnetically isolated paramagnetism observed for 1. The results of comparative magneto-structural investigations of 1 and 2 suggest that the pathway for the weak anti-ferromagnetic super-exchange in 2 might be through a Cu-Br${\cdots}$Br-Cu contact.

• YAKHAK HOEJI
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• v.53 no.4
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• pp.222-227
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• 2009

Human topoisomerase I (Topo I) plays a pivotal role in cell replication, transcription and repair and, therefore, is an important anti-cancer target. 20S-camptothecin (CPT) is a representative Topo I inhibitor. Compounds belonging to CPT family inhibit the religation step of Topo I-DNA by binding to the DNA cleavage site. Computational docking studies with Surflex-Dock were carried out to investigate the binding modes between Topo I-DNA binary complex structure and the ligand such as 20S-CPT and 9,10-substituted 20S-CPT analogues. The docking results demonstrated that most of the compounds with $IC_{50}$ value under $0.5{\mu}M$ intercalated exactly between the -1 and +1 DNA bases, deeply toward the cleavage site. The complex was stabilized by hydrogen-bonding and hydrophobic interactions with both the enzyme and the DNA. The compounds with $IC_{50}$ value above $0.5{\mu}M$ were poorly docked and did not intercalate. In addition, the docking results confirmed the overall correlation between the $IC_{50}$ values and docking scores, indicating the possible use of the modeling for the prediction of biological activity and design of potential inhibitors.

• Elastomers and Composites
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• v.39 no.1
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• pp.42-50
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• 2004

In this work, the diglycidylether of bisphenol A (DGEBA) and modified polyurethane (PU) blends were initiated by N-benzylpyrazinium hexafluoroantimonate (BPH). The cure and fracture toughness of neat DGEBA with the addition of PU were investigated. The cure properties of DGEBA/PU blend system were examined by DSC and near-IR measurements. The fracture touhtness were investigated by measuring the critical stress intensity factor ($K_{IC}$) and the critical strain energy release rate ($G_{IC}$). According to the results, the maximum values of owe activation energy ($E_a$) and conversion (${\alpha}$) were found at 10 phr of PU. Also the $K_{IC}$ showed a similar behavior with the results of conversion. These results were probably due to increase of crosslinking density in the blends resulted from increase of the hydrogen bonding between the hydroxyl groups of DGEBA and isocyanate groups of PU.