• Membrane Journal
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• v.15 no.2
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• pp.165-174
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• 2005

Sulfonated poly(styrene-ethylene-butadiene-styrene) (SSEBS)-clay hybrid membranes were prepared by solution method. In the preparation of hybrid membrane, the amount of clay content was fixed to 5 phr and montmorillonite (MMT) was fully exfoliated by the SEBS and it was confirmed by X-ray diffraction method. D-spacing of the characteristic peak from MMT plate in WAXD was fully diminished. Gas permeability, mechanical properties and thermal properties of the SSEBS-clay hybrid membranes were investigated. Gas permeability through the SSEBS-clay hybrid membranes decreased due to increased tortuosity made by exfoliation of clay in SEBS.

• The Korean Journal of Ceramics
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• v.5 no.4
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• pp.379-385
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• 1999

Minute boehmite crystals with high aspect rations, which were hydrothermally synthesized from gibbsite in $Ba(OH)_2$ solution, occluded Ba with the Ba/Al molar ratio of about 0.03 in their interlayers. Their surface areas were about 14$\m^2$/g. The Ba-intercalated bohemite samples were partly used for producing $BaAl_{12}O){19}$ with low sinterability by externally supplementing $Ba(OH)_2$, and for forming transient aluminas. The surface area of $BaAl_{12}O){19}$ obtained by firing at $1500^{\circ}C$ for 3 h was 5.3$\m^2$/g, which was significantly lower than 12$\m^2$/g of the sol-gel origin. While a mixture ${\gamma}$-alumina and BaO is known to from $BaAl_{12}O){19}$ at $1200^{\circ}C$, solid state reaction between η-alumina transformed from the Ba-intercalated boehmite and BaO formed from $Ba(OH)_2$ deposited on the boehmite started above $1300^{\circ}C$. This suggests that large sized $Ba^{2+}$ ion occluded in η-alumina considerably suppresses the diffusion of $Al^{3+}$ ion. The surface area of the Ba-intercalated boehmite fired at $1400^{\circ}C$ for 3h was as high as 14$\m^2$/g indicative of its potential applicability to combustion catalysts. But it was decreased to 5.0$\m^2$/g after firing at $1500^{\circ}C$ for 3 h, accompanied by abrupt formations of $\alpha$-alumina and $BaAl_{12}O){19}$ as main products. The suppression of $\alpha$-alumina formation up to $1400^{\circ}C$ also suggests the significant blocking effect of $Ba^{2+}$ ion on the diffusion of the component ions.

• Applied Chemistry for Engineering
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• v.24 no.5
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• pp.489-493
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• 2013

The most common carbonaceous anode materials of lithium ion batteries (natural graphite, artificial graphite, hard carbon, and mesocarbon microbeads) were utilized as an electrode in lithium ion capacitors. It could be able to enhance the energy density of capacitors due to the intercalation of lithium ion. In this work, the properties of capacitors using the symmetric electrode were measured by organizing coin cell typed capacitors. Also, we made other capacitors having pre-intercalated lithium ions at one side of the electrode. The results of electrochemical measurements for these capacitors show that the storage capacitance was appeared. In other words, if the migration of lithium ions is supplied continuously in the electrolytes, lithium ions can be diffused into the carbonaceous materials. And it results in the improvement of capacitance compared to only using symmetric carbonaceous electrodes. Also, we conducted the same measurement with graphene oxide having a the large specific area in the same condition. Herein, we recognized that the large specific area is extremely important for supercapacitors.

• Bulletin of the Korean Chemical Society
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• v.27 no.8
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• pp.1175-1180
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• 2006

Si-C composites were prepared by the carbonization of polyaniline (PAn) coated on silicone powder. The physical and electrochemical properties of the Si-C composites were characterized by particle-size analysis, X-ray diffraction, scanning electron microscopy, and battery electrochemical tests. The average particle size of Si was increased by the coating of Pan but somewhat reduced by the carbonization to give silicone-carbon composites. The co-existence of crystalline silicone and amorphous-like carbon was confirmed by XRD analyses. SEM photos showed that the silicone particles were well covered with carbonaceous materials, depending on the PAn content. Si-C$\mid$Li cells were fabricated using the Si-C composites and tested using galvanostatic charge-discharge. Si-C$\mid$Li cells gave better electrochemical properties than Si|Li cells. Si-C$\mid$Li cells using Si-C from HCl-undoped precursor PAn showed better electrochemical properties than precursor PAn doped in HCl. The addition of an electrolyte containing 4-fluoroethylene carbonate (FEC) increased the initial discharge capacity. Also, another electrochemical test, the galvanostatic charge-discharge test with GISOC (gradual increasing of the state of charge) was carried out. Si-C(Si:PAn = 50:50 wt. ratio)|Li cell showed 414 mAh/g of reversible specific capacity, 75.7% of IIE (initial intercalation efficiency), 35.4 mAh/g of IICs (surface irreversible specific capacity).

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.10a
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• pp.107-113
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• 1995

Basement membrane laminin is a multidomain glycoprotein that interacts with itself, heparin and cells. The distal long arm plays major cell and heparin interactive roles. The long arm consists of three subunits (A, B1, B2) joined in a coiled-coil rod attached to a terminal A chain globule (G). The globule is in turn subdivided into five subdomains (Gl-5). In order to analyze the functions of this region, recombinant G domains (rG, rAiG, rG5, rGΔ2980-3028) were expressed in Sf9 insect cells using a baculovirus expression vector. A hybrid molecule (B-rAiG), consisting of recombinant A chain(rAiG) and the authentic B chains (E8-B)was assembled in vitro. The intercalation of rAiG into E8-B chains suppressed a heparin binding activity identified in subdomain Gl-2. By the peptide napping and ligand blotting, the relative affinity of each subeomain to heparin was assigned as Gl> G2= G4> G5> G3, such that G1 bound strongly and G3 not at all. The active heparin binding site of G domain in intact laminin appears to be located in G4 and proximal G5. Cell binding was examined using fibrosarcoma Cells. Cells adhered to E8, B-rAiG, rAiG and rG, did not bind on denatured substrates, poorly bound to the mixture of E8-B and rG. Anti-${\alpha}$6 and anti-${\beta}$1 integrin subunit separately blocked cell adhesion on E8 and B-rAiG, but not on rAiG. Heparin inhibited cell adhesion on rAiG, partially on B-rAiG, and not on E8. In conclusion, 1) There are active and cryptic cell and heparin binding activities in G domain. 2) Triple-helix assembly inactivates cell and heparin binding activities and restores u6131 dependent cell binding activities.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.185.2-185.2
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• 2014

We have studied the atomic and electronic structure of graphene nanoribbons (GNRs) on a hexagonal boron nitride (h-BN) sheet with intercalated atoms using first-principles calculations. The h-BN sheet is an insulator with the band gap about 6 eV and then it may a good candidate as a supporting dielectric substrate for graphene-based nanodevices. Especially, the h-BN sheet has the similar bond structure as graphene with a slightly longer lattice constant. For the computation, we use the Vienna ab initio simulation package (VASP). The generalized gradient approximation (GGA) in the form of the PBE-type parameterization is employed. The ions are described via the projector augmented wave potentials, and the cutoff energy for the plane-wave basis is set to 400 eV. To include weak van der Waals (vdW) interactions, we adopt the Grimme's DFT-D2 vdW correction based on a semi-empirical GGA-type theory. Our calculations reveal that the localized states appear at the zigzag edge of the GNR on the h-BN sheet due to the flat band of the zigzag edge at the Fermi level and the localized states rapidly decay into the bulk. The open-edged graphene with a large corrugation allows some space between graphene and h-BN sheet. Therefore, atoms or molecules can be intercalated between them. We have considered various types of atoms for intercalation. The atoms are initially placed at the edge of the GNR or inserted in between GNR and h-BN sheet to find the effect of intercalated atoms on the atomic and electronic structure of graphene. We find that the impurity atoms at the edge of GNR are more stable than in between GNR and h-BN sheet for all cases considered. The nickel atom has the lowest energy difference of ~0.2 eV, which means that it is relatively easy to intercalate the Ni atom in this structure. Finally, the magnetic properties of intercalated atoms between GNR and h-BN sheet are investigated.

• Membrane Journal
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• v.16 no.2
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• pp.85-105
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• 2006

Poly(lactic acid) is a linear aliphatic thermoplastic polyester, produced by the ring-opening polymerization of lactides and the lactic acid monomers, which are obtained from the fermentation of sugar feed stocks, corn, etc. PLA has high mechanical, thermal plasticity, fabric-ability, and biocompatibility, So PLA is a promising polymer far various end-use applications. In recent time, the intercalation of polymers from either solution or the melt in the silicate galleries of clay is the best technique to prepare nanocompoiste material which often exhibit remarkable improvement of mechanical, thermal, optical and physicochemical properties when compared with the pure polymer or conventional composites. Layered silicate is naturally abundant, economic, and more importantly benign to the environment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.1
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• pp.15-22
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• 2018

Alpha-pinene is an organic compound that possesses antibiotic and anti-parasitic activities. In this study, we developed a layered nanocomposite to combat against Miamiensis avidus which causes scuticociliatosis in the olive flounder Paralichthys olivaceus. We used a solid-solid reaction to develop the layered nanocomposite, incorporating-pinene ($C_{10}H_{16}$) into organically modified montmorillonite. We used cetyltrimethylammonium cations as the interlayered modifier for the adsorption of hydrophobic pinene molecules. The X-ray diffraction patterns of the nanocomposite structure showed that the basal spacing increased from $9.6{\AA}$ to $30.4{\AA}$. Interestingly, the fraction of ${\alpha}$-pinene released remained constant for a long period of time (228 h) due to the layered nature of the nanocomposite. Additionally, optical microscopic images of the treated scuticociliatids revealed that their cells were lysed, and this effect increased with the increasing concertration of ${\alpha}$-pinene. Histopathological assessment of ${\alpha}$-pinene nanocomposite-treated olive flounder gills revealed no significant morphological changes, even at the highest concentration of the ${\alpha}$-pinene. The nanocomposite has several advantages, including easy handling, high solubility, low toxicity, and the easy formulation of granules or powder, which improve the pesticidal activity of ${\alpha}$-pinene. Collectively, our results suggest that ${\alpha}$-pinene nanocomposite may be a useful treatment against scuticociliatosis.

• Progress in Superconductivity
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• v.12 no.1
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• pp.51-56
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• 2010

$^{13}C$ NMR (nuclear magnetic resonance) measurements have been performed to investigate the local electronic structure of a superconducting graphite intercalation compound $CaC_6$ ($T_c$ = 11.4 K). A large number of single crystals were stacked and sealed in a quartz tube for naturally abundant $^{13}C$ NMR. The spectrum, Knight shift, linewidth, and spin-lattice relaxation time $T_1$ were measured in the normal state as a function of temperature down to 80 K at 8.0 T perpendicular to the c-axis. The $^{13}C$ NMR spectrum shows a single narrow peak with a very small Knight shift. The Knight shift and the linewidth of the $^{13}C$ NMR are temperature-independent around, respectively, +0.012% and 1.2 kHz. The spin-lattice relaxation rate, $1/T_1$, is proportional to temperature confirming a Korringa behavior as for non-magnetic metals. The Korringa product is measured to be $T_1T\;=\;210\;s{\cdot}K$. From this value, the Korringa ratio is deduced to be $\xi$ = 0.73, close to unity, which suggests that the independent-electron description works well for $CaC_6$, without complications arising from correlation and many-body effects.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.465-472
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• 2009

The technologies for improving the capacity of hydrogen storage were investigated and the recent data of hydrogen storage by using various porous carbon materials were summarized. As the media of hydrogen storage, activated carbon, carbon nanotube, expanded graphite and activated carbon fiber were mainly investigated. The hydrogen storage in the carbon materials increased with controlled pore size about 0.6~0.7 nm. In case of catalyst, transition metal and their metal oxide were mainly applied on the surface of carbon materials by doping. Activated carbon is relatively cheap because of its production on a large scale. Carbon nanotube has a space inside and outside of tube for hydrogen storage. In case of graphite, the distance between layers can be extended by intercalation of alkali metals providing the space for hydrogen adsorption. Activated carbon fiber has the high specific surface area and micro pore volume which are useful for hydrogen storage. Above consideration of research, porous carbon materials still can be one of the promising materials for reaching the DOE target of hydrogen storage.