• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1317-1322
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• 2014

Membrane disruption by an antimicrobial peptide (AMP) was investigated by measuring the $^2H$ solid-state nuclear magnetic resonance spectra of 1-palmitoyl-$d_{31}$-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC_$d_{31}$) in mixtures of POPC_$d_{31}$/cholesterol and either magainin 2 or aurein 3.3 deposited on thin cover-glass plates. The line shapes of the experimental $^2H$ solid-state nuclear magnetic resonance (SSNMR) spectra were best simulated by assuming the coexistence of a mosaic spread of bilayers containing pore structures and a fasttumbling isotropic phase or a hexagonal phase. Within a few days of incubation in a hydration chamber, an isotropic phase and a pore structure were induced by magainin 2, while in case of aurein 3.3 only an isotopic phase was induced in the presence of a bilayer phase. After an incubation period of over 100 days, alignment of the bilayers increased and the amount of the pore structure decreased in case of magainin 2. In contrast with magainin 2, aurein 3.3 induced a hexagonal phase at the peptide-to-lipid ratio of 1/20 and, interestingly, cholesterol was not found in the hexagonal phase induced by aurein 3.3. The experimental results indicate that magainin 2 is more effective in disrupting lipid bilayers containing cholesterol than aurein 3.3.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.347.2-347.2
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• 2016

Recently, in order to improve the performance of the colloidal quantum dot solar cells (CQDSCs), various efforts such as the modification of the cell architecture and surface treatment for quantum dot (QD) passivation have been made. Especially, the incorporation of halides into the QD matrix was reported to improve the performances significantly via passivating QD trap states that lower the life-time of the minority-carrier. In this work, we fabricated a lead sulfide (PbS) QD bilayer treated with different ligands and utilized it as a photoactive layer of the CQDSCs. The bottom and top PbS layer was treated using metal iodide ($MI_x$ and butanedithiol (BuDT), respectively. All the depositions and ligand treatments were carried out in air using layer-by-layer spin-coating process. The fabrication of the active layers as well as the n-type zinc oxide (ZnO) layer was successfully carried out on the bendable indium-tin-oxide (ITO)-coated polyethylene terephthalate (PET) substrate, which implies that this technique can be applied to the fabrication of flexible and/or wearable solar cells. The power conversion efficiency (PCE) of the CQDSCs with the architecture of $PET/ITO/ZnO/PbS-MI_x/PbS-BuDT/MoO_x/Ag$ reached 4.2 %, which is significantly larger than that of the cells with single QD (PbS-BuDT) layer.

• Journal of the Korean Ceramic Society
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• v.55 no.6
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• pp.576-580
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• 2018

In this study, a small amount of CoO was added to commercial Gd-doped $CeO_2$ (GDC) powder. The CoO addition greatly enhanced sinterability at low temperatures, i.e., more than 98% of relative density was achieved at $1,000^{\circ}C$. When GDC/8YSZ (8 mol% yttrium stabilized zirconia) bilayers were sintered, Co-doped GDC showed excellent adhesion to the YSZ electrolyte. Transmission electron microscope (TEM) analysis showed that there were no traces of liquid films at the grain boundaries of GDC, whereas liquid films were observed in the Co-doped GDC sample. Because liquid films facilitate particle rearrangement and migration during sintering, mechanical stresses at the interface of a bilayer, which are developed based on different densification rates between the layers, might be reduced. In spite of $Co^{2+}$ doping in GDC, the electrical conductivity was not significantly changed, relative to GDC.

• Korea-Australia Rheology Journal
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• v.15 no.1
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• pp.1-7
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• 2003

A new method is introduced to build up organic/organic multilayer films composed of cationic poly(allylamine hydrochloride) (PAH) and negatively charged poly (sodium 4-styrenesulfonate) (PSS) using the spinning process. The adsorption process is governed by both the viscous force induced by fast solvent elimination and the electrostatic interaction between oppositely charged species. On the other hand, the centrifugal and air shear forces applied by the spinning process significantly enhances desorption of weakly bound polyelectrolyte chains and also induce the planarization of the adsorbed polyelectrolyte layer. The film thickness per bilayer adsorbed by the conventional dipping process and the spinning process was found to be about 4 ${\AA}$ and 24 ${\AA}$, respectively. The surface of the multilayer films prepared with the spinning process is quite homogeneous and smooth. Also, a new approach to create multilayer ultrathin films with well-defined micropatterns in a short process time is Introduced. To achieve such micropatterns with high line resolution in organic multilayer films, microfluidic channels were combined with the convective self-assembly process employing both hydrogen bonding and electrostatic intermolecular interactions. The channels were initially filled with polymer solution by capillary pressure and the residual solution was then removed by the .spinning process.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.3
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• pp.323-327
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• 1993

The effect of soyasaponin on the liposomal phospholipid membrane was investigated by differential scanning calorimetry (DSC). Soyasaponins were obtained and the enthalpy changes and the sizes of cooperative unit of the transition were calculated. The thermograms of L-$\alpha$-dimyristoyl phosphatidylcholine (DMPC) incorporated with soyasaponin showed that the phase transition temperature was significantly lowered and the peak was broadened. This was attributed to the possibility that incorporation of soyasaponin into the lipid bilayers reduced the cooperative unit of phospholipid bilayers. These results indicate soyasaponin might have significant effect on the fluidity of biological membrane.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.145-148
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• 2003

The resistance of docosahexaenoic acid (DHA) incorporated $L-{\alpha}-phosphatidyl$ -choline (PC) liposomes against autoxidation was studied for application to food and cosmetic industry. For the preparation of vitamin-C/calcium alginate gel entrapped DHA-PC-liposomes (AVDLs), DHA incorporated PC bilayer was hydrated with vitamin-C containing calcium alginate solution, and the fraction containing liposome was suspended in $CaCl_2$ solution. DHA loading efficiency was calculated by TLC scanning method The morphological examination of AVDLs was performed with transmission electron microscopy (TEM) and lipid peroxidation was measured with an assay for thiobarbituric acid reactive substance (TBARS). DHA loading efficiency was about 17 % of initial loading volume, and when AVDLr containing 0.2 % vitamin C, lipid oxidation was minimized.

• Journal of Chest Surgery
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• v.25 no.4
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• pp.347-355
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• 1992

The precise mechanism of the Excitation-Contraction Coupling is still uncertain. But the concept that Ca2+ induced Ca2+ release [CICR] from the Ryanodine receptor in the sarcoplasmic reticulum [foot structure] may play a major role in E-C coupling has been widely accepted since 1970`s. It is believed that increased cytosolic Ca2+ followed by CICR is main contributor for E-C coupling of striated muscle. Resulting phenomena of ischemic /post-reperfusion myocyte is increased cytosolic Ca2+, even to the absence of Ca2+ in reperfusate. So intracellular inhibitor to CICR might prevent the ischemic and reperfusion damage of myocardial cells. The relatively purified foot protein, especially heavy sarcoplasmic reticulum rich, of the skeletal muscle was incorporated into the black lipid bilayer [Phosphatidyl ethanolamine: Phosphatidyl serine=l: 1]. Under the steady state of membrane potential [+20 mV], ionic current through Ryanodine receptor was measured with Cs+ as charge carrier. In the cis chamber [Cytoplasmic side], Mg2+ strongly inhibited CICR of Ryanodine receptor[Kd=6.2 nM]. In conclusion, naturally existing intracellular free Mg2+ can inhibit CICR from intracellular Ca2+ reservior [heavy SR]. So post-ischemic or post-reperfusing myocardium could be preserved using additional free Mg2+ in cardioplegic solution or reperfusate, otherwise the optimal concentration is undetermined.

• Macromolecular Research
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• v.17 no.4
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• pp.271-275
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• 2009

This paper describes the out-of-plane order of a liquid crystalline(LC) methacrylate copolymer(3) comprised of a methacrylate(1) with a 4-styrylpyridine moiety as the photo-cyclodimerizable group and a benzoate moiety as the mesogenic group in the side chain, and another methacrylate(2) with a 4-(4-methoxyphenyl)benzoate moiety as the mesogenic group. The composition of 1 and 2 units in 3 was estimated to have a molar ratio of 54.2:45.8 by $^{1}H$ NMR spectroscopy. The X-ray diffraction study revealed that the copolymer forms a partial bilayer smectic structure. The copolymer gave rise to a high out-of-plane order parameter of about 0.74 in a wide LC temperature range of $110{\sim}160^{\circ}C$ after linearly polarized, UV light irradiation and subsequent annealing. Moreover, the external reflection IR analysis indicated that excess UV-light irradiation makes the out-of-plane LC structure of the copolymer appear in a higher and wider temperature range.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.1
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• pp.23-29
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• 1997

Effects of Co thickness on the formation of epitaxial $CoSi_2$ from the Co/Ti bilayer have been investigated. Ti and Co were sequentially deposited with the Ti thickness fixed at 5 or 10nm, while the Co thickness was varied from 5 to 30nm. The metal-deposited samples were then rapidly thermal-annealed in $N_2$ at $900^{\circ}C$ for 20 sec. Material properties of $CoSi_2$ thin films were analyzed by the 4-point probe, XRD, AES, andXTEM. When the as-deposited Co thickness was below 15nm, the $CoSi_2$ with high resistivity and rough interface was formed. On the other hand, when the Co thickness was above 15 nm, the epitaxial $CoSi_2$ with the resistivity of about 16 ~ 19 $\mu\Omega.cm$, uniform composition and thickness and flat interface was formed. Initial Ti thickness has sizable effect on the formation of $CoSi_2$, when the Co layer was very thin (~ 5 nm). But there was no significant effect of the Ti thickness for the initial Co thickness of above 15 nm.

• Journal of the Korean Magnetic Resonance Society
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• v.15 no.1
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• pp.25-39
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• 2011

Syndecan-4 is a transmembrane heparan sulfate proteoglycan, which is a coreceptor with integrins in cell adhesion. To get better understand the mechanism and function of Syndecan-4, it is critical to elucidate the three-dimensional structure of a single transmembrane spanning region of them. Unfortunately, it is hard to prepare the peptide because syndecan-4 is membrane-bound protein that transverse the lipid bilayer of the cell membrane. Generally, the preparation of transmembrane peptide sample is seriously difficult and time-consuming. In fact, high yield production of transmembrane peptides has been limited by experimental adversities of insufficient yields and low solubility of peptide. Here, we demonstrate experimental processes and results to optimize expression, purification, and NMR measurement condition of Syndecan-4 transmembrane peptide.