• Molecules and Cells
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• v.45 no.1
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• pp.6-15
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• 2022

Phase separation is a thermodynamic process leading to the formation of compositionally distinct phases. For the past few years, numerous works have shown that biomolecular phase separation serves as biogenesis mechanisms of diverse intracellular condensates, and aberrant phase transitions are associated with disease states such as neurodegenerative diseases and cancers. Condensates exhibit rich phase behaviors including multiphase internal structuring, noise buffering, and compositional tunability. Recent studies have begun to uncover how a network of intermolecular interactions can give rise to various biophysical features of condensates. Here, we review phase behaviors of biomolecules, particularly with regard to regular solution models of binary and ternary mixtures. We discuss how these theoretical frameworks explain many aspects of the assembly, composition, and miscibility of diverse biomolecular phases, and highlight how a model-based approach can help elucidate the detailed thermodynamic principle for multicomponent intracellular phase separation.

• Elastomers and Composites
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• v.57 no.1
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• pp.9-12
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• 2022

Herein, a facile approach for the development of effective and low-cost carbon precursors from acrylonitrile-butadiene-styrene (ABS) rubber is reported. ABS rubber with a negligible char yield can be converted into an excellent carbon precursor with approximately 54% char yield under a nitrogen atmosphere at 800℃ by simple iodine doping and subsequent heating at 110℃ under an inert atmosphere. The enhanced char yield is attributed to the improved intermolecular interactions between the ABS chains caused by the formation of covalent bonds between the butadiene segments, along with the newly developed charge-charge interactions and other indiscriminate radical-radical couplings. The charges and radicals involved in these interactions are also generated by iodine doping. We believe that this study will be useful for the development of low-cost carbon precursors.

• Journal of the Korean Chemical Society
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• v.67 no.4
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• pp.226-235
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• 2023

Chikungunya fever has a high morbidity rate in humans and is caused by chikungunya virus. There are no treatments available until now for this particular viral disease. The present study was carried out by selecting 19 flavonoids, which are available naturally in fruits, vegetables, tea, red wine and medicinal plants. The molecular docking of selected 19 flavonoids was carried out against the Chikungunya virus capsid protein using the Autodock4.2 software. Binding affinity analysis based on the Intermolecular interactions such as Hydrogen bonding and hydrophobic interactions and drug-likeness properties for all the 19 flavonoids have been carried out and it is found that the top four molecules are Chrysin, Fisetin, Naringenin and Biochanin A as they fit to the chikungunya protein and have binding energy of -8.09, -8.01, -7.6, and 7.3 kcal/mol respectively. This result opens up the possibility of applying these compounds in the inhibition of chikungunya viral protein.

• Journal of Photoscience
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• v.12 no.1
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• pp.25-32
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• 2005

Binding of N-Alkyl phenothiazines (NAP) to bovine serum albumin (BSA) was studied by spectroscopic methods.It was found that the phenothiazine ring common to all drugs makes major contribution to interaction. However, the nature of alkylamino group at position 10 influences the protein binding significantly. Stern-Volmer plots indicated the presence of static component in the quenching mechanism. The high magnitude of rate constant of quenching indicated that the process of energy transfer occurs by intermolecular interaction and thus the drug-binding site is in close proximity to tryptophan residues of BSA. Binding studies in presence of hydrophobic probe, 8-anilino-1-naphthalein-sulphonic acid showed that there is hydrophobic interaction between drug and the probe and they do not share common sites in BSA. Thermodynamic parameters obtained from data at different temperatures showed that the binding of NAP to BSA predominantly involve hydrophobic forces. The effects of some cations and anions common ions were investigated on NAP-BSA interactions. The CD spectrum of BSA in presence of drug showedthat binding of drug leads to change in the helicity of the protein.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.69-74
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• 2018

With the increasing development of industrial society and the availability of high quality electrical energy, the simplification of operation and maintenance procedures is required, in order to ensure the reliability and safety of electrical systems. In this paper, the dielectric breakdown characteristics of $N_2-O_2$ mixed gas solid insulation, which is used as an alternative to SF6 in various electric power facilities, are verified. When the gas mixture has a composition ratio similar to that of the atmosphere, the dielectric breakdown characteristics are relatively stabilized. It was confirmed that the breakdown voltage of the gas in the electrode near an equal electric field increased with increasing pressure according to Paschen's rule. The breakdown voltage of the surface increased linearly with increasing pressure, and the difference was caused by the mixing ratio of $O_2$ gas. This change in the surface insulation breakdown voltage was caused by the influence of the electrically negative $O_2$ gas and the intermolecular collision distance. In this study, the influence of the intermolecular impact distance was larger (than that in the absence of the electrically negative $O_2$ gas). The breakdown voltage relation applicable to Teflon according to the surface insulation characteristics was calculated. The characteristics of the surface insulation properties of Teflon, which is used as a solid insulation material, were derived as a function of pressure. It is thought that these results can be used as the basic data for the insulation design of electric power facilities.

• Journal of the Korean Chemical Society
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• v.18 no.5
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• pp.329-340
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• 1974

Sulfadiazine, $C_{10}H_{10}N_4O_2S$, forms monoclinic crystals of space group $P21}c$ from a mixture of acetone and ethanol with $a=13.71{\pm}0.04,\;b=5.84{\pm}0.03,\;c=15.11{\pm}0.05{\AA},\;{\beta}=115.0{\pm}0.3^{\circ}$, and four molecules per cell. Three dimensional photographic data were collected with $CuK\alpha$ radiation. The structure was determined using Patterson and Fourier synthesis methods and refined by block diagonal least-squares methods with isotropic thermal parameter for all non-hydrogen atoms. The final R value was 0.15 for the 1517 observed independent reflections. The dihedral angle between the planes through the benzene ring and the pyrimidine ring is $76^{\circ}$. The conformational angle formed by the projection of the S-C(5) bond with that of N(1)-C(1) where the projection is taken along the S-N(1) bond is $77^{\circ}$. The imino nitrogen atom, N(1), and pyrimidine nitrogen atom, N(3), form intermolecular $N-H{\cdots}N$ hydrogen bond between the molecules related by center of symmetry. Amino nitrogen atom, N(4), forms two intermolecular $N-H{\cdots}O$ hydrogen bonds, with O(1) and O(2) atoms of different molecules separated by b. A two dimensional network of hydrogen bonds form infinite molecular sheets parallel to the (100) plane. Adjacent sheets are bound together by van der Waals forces.

• Fibers and Polymers
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• v.7 no.4
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• pp.333-338
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• 2006

Silk fibroin (SF) fiber from the Antheraea pernyi silkworm was treated with a 1.23 N iodine-potassium iodide ($I_2-KI$) aqueous solution, and the structure and physical properties were investigated to clarify the effects of the iodine treatment. The noticeably high weight gain value of SF fiber, about 25 wt% was attributed to the absorption of polyiodide ions in the form of $I_3{^-}\;and\;I_5{^-}$. Fourier transform infrared spectroscopy and X-ray diffraction measurements suggested that polyiodide ions mainly entered the amorphous region. In addition, a new sharp reflection on the meridional direction, corresponding to a period of $7.0{\AA}$, was observed and indicated the possibility of the formation of mesophase structure of ${\beta}$-conformation chains. Dynamic viscoelastic measurements showed that the damping tan ${\delta}$ peak at $270^{\circ}C$ gradually shifted to lower temperature in the iodinated SF fibers, suggesting an enhancement of the molecular motion of the fibroin chains induced by the presence of polyiodide ions. With heating above $254^{\circ}C$, the iodine component introduced intermolecular cross-linking of SF, and the melt flow of the sample was inhibited. The thermal decomposition stability of fibroin molecules was greatly enhanced by iodine treatment.

• Analytical Science and Technology
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• v.18 no.5
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• pp.386-390
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• 2005

The zinc(II) complex, $Zn(NCS)_2(C_3H_4N_2S)_2$, I, has been synthesized and characterized by single crystal X-ray diffraction, thermal analysis and infrared spectroscopy. The complex I crystallizes in the triclinic system, $P\bar{1}$ space group with a = 7.587(1), b = 8.815(1), $c=12.432(2){\AA}$, ${\alpha}=75.584(8)$, ${\beta}=83.533(9)$, ${\gamma}=68.686(8)^{\circ}$, $V=750.0(2){\AA}^3$, Z = 2, $R_1=0.036$ and ${\omega}R_2=0.101$. The central Zn(II) atom has a tetrahedral coordination geometry, with the heterocyclic nitrogen atoms of 2-aminothiazole ligands and the nitrogen atoms of isothiocyanate ligands. The crystal structure is stabilized by one-dimensional networks of the intermolecular $N-H{\cdots}S$ hydrogen bonds between the amino group of 2-aminothiazole ligands and the sulfur atom of isothiocyanate ligands. Based on the results of thermal analysis, the thermal decomposition reaction of complex I was analyzed to have three distinctive stages such as the loss of 2-aminothiazole, the decomposition of isothiocyanate and the formation of metal oxide.

• Polymer(Korea)
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• v.39 no.3
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• pp.403-411
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• 2015

A series of hydrophobically associating fluorinated amphiphilic polyacrylamide copolymers with remarkably high heat resistance and salt tolerance were synthesized by free radical micellar copolymerization, using acrylamide (AM) and sodium 2-acrylamido-tetradecane sulfonate ($AMC_{14}S$) as amphiphilic monomers, and 2-(perfluorooctyl) ethyl acrylate (PFHEA) as hydrophobic monomer. The structure of the terpolymer was characterized by FTIR, $^1H$ NMR and $^{19}F$ NMR. The solution properties of the terpolymers were investigated in details, and the results showed that the terpolymer solution had strong intermolecular hydrophobic association as the concentration exceeded the critical association concentration 1.5 g/L. The terpolymer solution possessed high surface activity, viscoelasticity, excellent heat resistance, salt tolerance and shearing resistance. The viscosity retention rate of copolymer solution was as high as 59.9% under the condition of fresh wastewater, $85^{\circ}C$ and a 60-days aging test.

• Bulletin of the Korean Chemical Society
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• v.32 no.spc8
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• pp.3090-3093
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• 2011

Curcumin is a natural product with antioxidant, anti-inflammatory, antiviral and antifungal functions. As it is known that the excited state intramolecular hydrogen transfer of curcumin are related to its medicinal antioxidant mechanism, we investigated its excited state dynamics by using femtosecond transient absorption spectroscopy in an effort to understand the molecule's therapeutic effect in terms of its photophysics and photochemistry. We found that stronger intermolecular hydrogen bonding with solvents weakens the intramolecular hydrogen bonding and decelerates the dynamical process of the enolic hydrogen. Exceptions are found in methanol and ethylene glycol due to their nature as simultaneous hydrogen bonding donor-acceptor and high viscosity solvent, respectively.