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Han S.S.,Korea Research Institute of Standards and Science | Jung H.,Ulsan National Institute of Science and Technology | Jung D.H.,Insilicotech Co. | Choi S.-H.,Insilicotech Co. | Park N.,Ulsan National Institute of Science and Technology
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

The hydrogen spillover mechanism has been discussed in the field of hydrogen storage and is believed to have particular advantage over the storage as metal or chemical hydrides. We investigate conditions for practicality realizing the hydrogen spillover mechanism onto carbon surfaces, using first-principles methods. Our results show that contrary to common belief, types of hydrogenation configurations of graphene (the aggregated all-paired configurations) can satisfy the thermodynamic requirement for room-temperature hydrogen storage. However, the peculiarity of the paired adsorption modes gives rise to a large kinetic barrier against hydrogen migration and desorption. It means that an extremely high pressure is required to induce the migration-derived hydrogenation. However, if mobile catalytic particles are present inside the graphitic interstitials, hydrogen migration channels can open and the spillover phenomena can be realized. We suggest a molecular model for such a mobile catalyst which can exchange hydrogen atoms with the wall of graphene. © 2012 American Physical Society.

Odkhuu D.,Insilicotech Co. | Odkhuu D.,Ulsan National Institute of Science and Technology | Jung D.H.,Insilicotech Co. | Lee H.,Ulsan National Institute of Science and Technology | And 4 more authors.
Carbon | Year: 2014

The inclusion of heptagonal, octagonal, or larger rings in an sp 2-bonded carbon network introduces negative Gaussian curvature that can lead to a high network porosity. Here we investigated a particular negatively curved nonplanar sp2-carbon structure namely 688P schwarzite, with a view toward the possible use of negatively curved carbons as lithium ion battery anodes. Our first principles calculations show that the presence of pores in schwarzites can lead to three-dimensional Li ion diffusion paths with relatively small energy barriers. We calculated the binding energy of Li (which donates 1 electron to the schwarzite) in different positions in the schwarzite structure, and the open-circuit voltage (OCV) with respect to Li metal and found that this schwarzite has a positive OCV for a Li concentration as high as LiC4. The advantages of the particular schwarzite studied here for use as an anode are expected to be present in other sp 2-bonded carbon networks that feature large polygonal rings. © 2013 Elsevier Ltd. All rights reserved.

Chai H.-H.,South Korean National Institute of Animal Science | Lim D.,South Korean National Institute of Animal Science | Lee S.-H.,South Korean National Institute of Animal Science | Chai H.-Y.,Korea National Institute of Helth | Jung E.,Insilicotech Co.
International Journal of Molecular Sciences | Year: 2014

The activated mammalian CAPN-structures, the CAPN/CAST complex in particular, have become an invaluable target model using the structure-based virtual screening of drug candidates from the discovery phase to development for over-activated CAPN linked to several diseases, such as post-ischemic injury and cataract formation. The effect of Ca2+-binding to the enzyme is thought to include activation, as well as the dissociation, aggregation, and autolysis of small regular subunits. Unfortunately, the Ca2+-activated enzyme tends to aggregate when provided as a divalent ion at the high-concentration required for the protease crystallization. This is also makes it very difficult to crystallize the whole-length enzyme itself, as well as the enzyme-inhibitor complex. Several parameters that influence CAPN activity have been investigated to determine its roles in Ca2+-modulation, autoproteolysis, phosphorylation, and intracellular distribution and inhibition by its endogenous inhibitor CAST. CAST binds and inhibits CAPN via its CAPN-inhibitor domains (four repeating domains 1-4, CAST1-4) when CAPN is activated by Ca2+-binding. An important key to understanding CAPN1 inhibition by CAST is to determine how CAST interacts at the molecular level with CAPN1 to inhibit its protease activity. In this study, a 3D structure model of a CAPN1 bound bovine CAST4 complex was built by comparative modeling based on the only known template structure of a rat CAPN2/CAST4 complex. The complex model suggests certain residues of bovine CAST4, notably, the TIPPKYQ motif sequence, and the structural elements of these residues, which are important for CAPN1 inhibition. In particular, as CAST4 docks near the flexible active site of CAPN1, conformational changes at the interaction site after binding could be directly related to CAST4 inhibitory activity. These functional interfaces can serve as a guide to the site-mutagenesis in research on bovine CAPN1 structure-function relationships for the design of small molecules inhibitors to prevent uncontrolled and unspecific degradation in the proteolysis of key protease substrates. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

Lee W.,Seoul National University | Yuk S.B.,Seoul National University | Choi J.,Seoul National University | Jung D.H.,Insilicotech Co. | And 3 more authors.
Dyes and Pigments | Year: 2012

For the liquid crystal display (LCD) black matrix (BM) with a low dielectric constant and high light absorption property, it is advantageous to employ dyes instead of carbon black or pigments. For this purpose, the dyes should have high solubility in industrial organic solvents. For improved solubility in industrial solvents, three metal-free phthalocyanines (PC), peripherally substituted with bulky groups, were synthesized and dye-based BMs were fabricated. The solubility as well as the spectral and thermal properties of the dyes were examined, and the optical, thermal and dielectric properties of a dye-based black matrix were tested. The greenish phthalocyanine dyes with high molar extinction coefficients and high thermal stability showed enhanced solubility in industrial solvents as a result of the greater steric hindrance among the dye molecules and higher affinity between the dye molecules and solvents. The dye-based BMs had low dielectric constants and exhibited superior optical properties and satisfactory thermal stability. © 2011 Elsevier Ltd. All rights reserved.

Kim D.,Insilicotech Co. | Kim D.,Korea University | Jung D.H.,Insilicotech Co. | Kim K.-H.,Insilicotech Co. | And 4 more authors.
Journal of Physical Chemistry C | Year: 2012

On the basis of our modeling of pillared covalent organic frameworks (PCOFs) with pyridine molecules inserted between the COF-1 layers, we propose that the surface area and free volume of storage materials should be balanced to increase the gravimetric and volumetric hydrogen uptake capacities. Density functional theory and grand canonical Monte Carlo simulations show that these PCOFs have significantly improved gravimetric and volumetric hydrogen storage capacities of 8.8-10.0 wt % and 58.7-61.7 g L -1, respectively. © 2011 American Chemical Society.

Jung E.,Insilicotech Co.
Journal of computer-aided molecular design | Year: 2012

Using phage display technique, we identified tissue-targeting peptide sets that recognize specific tissues (bone-marrow dendritic cell, kidney, liver, lung, spleen and visceral adipose tissue). In order to rapidly evaluate tissue-specific targeting peptides, we performed machine learning studies for predicting the tissue-specific targeting activity of peptides on the basis of peptide sequence information using four machine learning models and isolated the groups of peptides capable of mediating selective targeting to specific tissues. As a representative liver-specific targeting sequence, the peptide "DKNLQLH" was selected by the sequence similarity analysis. This peptide has a high degree of homology with protein ligands which can interact with corresponding membrane counterparts. We anticipate that our models will be applicable to the prediction of tissue-specific targeting peptides which can recognize the endothelial markers of target tissues.

Park Y.,Catholic University of Korea | Kim S.,Catholic University of Korea | Lee J.-H.,Chungbuk National University | Jung D.H.,Insilicotech Co. | And 2 more authors.
Organic Electronics: physics, materials, applications | Year: 2010

A promising class of blue-violet emitters based on a new functional core, the indenopyrazine group, has successfully been synthesized for the first time by substitution with bulky m-terphenyl side groups in the ortho, meta, or para positions. There are larger blue shifts in the UV-visible absorption and PL spectra of the synthesized ortho- and para-substituted derivatives than in those of the meta-substituted derivative. Molecular calculations verified that these differences are due to the variation in the π-conjugation length of the derivatives with the position at which the side group is attached to the indenopyrazine core. When the synthesized compounds were used as emitting layers in non-doped OLED devices, a related trend was observed in their optical properties. In particular, the OLED containing the para-substituted derivative was found to exhibit excellent characteristics, with maximum EL emission at 423 nm, a full width at half maximum of 42 nm, pure violet emission with CIE coordinates (0.173, 0.063), and an external quantum efficiency of 1.88%. © 2010 Elsevier B.V. All rights reserved.

Chai H.-H.,South Korean National Institute of Animal Science | Lim D.,South Korean National Institute of Animal Science | Jung E.,Insilicotech Co. | Choi B.-H.,South Korean National Institute of Animal Science | Cho Y.-M.,South Korean National Institute of Animal Science
Molecules | Year: 2014

HCV-induced CAPN activation and its effects on virus-infected cells in a host-immune system have been studied recently. It has been shown that the HCV-nonstructural 5A protein acts as both an inducer and a substrate for host CAPN protease; it participates in suppressing the TNF-α-induced apoptosis response and downstream IFN-induced antiviral processes. However, little is known regarding the disturbance of antiviral responses generated by bovine CAPN activation by BVDV, which is a surrogate model of HCV and is one of the most destructive diseases leading to great economic losses in cattle herds worldwide. This is also thought to be associated with the effects of either small CAPN inhibitors or the natural inhibitor CAST. They mainly bind to the binding site of CAPN substrate proteins and competitively inhibit the binding of the enzyme substrates to possibly defend against the two viruses (HCV and BVDV) for anti-viral immunity. To devise a new stratagem to discover lead candidates for an anti-BVDV drug, we first attempted to understand the bovine CAPN-CAST interaction sites and the interaction constraints of local binding architectures, were well reflected in the geometry between the pharmacophore features and its shape constraints identified using our modeled bovine CAPN1/CAST4 complex structures. We propose a computer-aided molecular design of an anti-BVDV drug as a mimetic CAST inhibitor to develop a rule-based screening function for adjusting the puzzle of relationship between bovine CAPN1 and the BVDV nonstructural proteins from all of the data obtained in the study. © Molecules 2014.

Han S.S.,Korea Research Institute of Standards and Science | Choi S.-H.,Insilicotech Co. | Van Duin A.C.T.,Pennsylvania State University
Chemical Communications | Year: 2010

We introduce the reactive force field (ReaxFF) simulation to predict the hydrolysis reactions and water stability of metal-organic frameworks (MOFs) where the simulation showed that MOF-74 has superior water-resistance compared with isoreticular IRMOF-1 and IRMOF-10. © 2010 The Royal Society of Chemistry.

Disclosed does a porous crystal comprising ammonia borane in which the ammonia borane is chemically bonded thereto by a chemical reaction while a porous crystal structure is maintained.

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