• Analytical Science and Technology
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• v.13 no.1
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• pp.66-71
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• 2000

The intercalated compound of dodecanesulfonate into hydrated cobalt was synthesized. The compound shows a layered structure as determined by high temperature X-ray diffraction. The layer distance of the product is increased from $19.1{\AA}$ to $34.7{\AA}$ by increasing the temperature from $30^{\circ}C$ to $200^{\circ}C$. We can control the layer distance by varying the temperature which is accomplished by changing from the monolayer to the bilayer structure of the intercalated dodecanesulfonate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.92-95
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• 2005

The silver photodoping effect in amorphous AsGeSeS chalcogenide thin films for holographic recording has been investigated using a HeNe laser ($\lambda$=632.8 nm). The chalcogenide films prepared in this work were thinner in comparison with the penetration depth of recording light ($d_p$=1.66 mm). The variation of the diffraction efficiency $(\eta)$ in amorphous chalcogende films exhibits a tendency, independently of the Ag photodoping. That is, n increases relatively rapidly at the beginning of the recording process, reaches the maximum $({\eta}_{max})$ and slowly decreases. In addition, the value of ${\eta}_{max}$ depends strongly on chalcogenide film thickness(d) and its peak among the films with d = 40, 80, 150, 300, and 633 nm is observed at d = 150 nm (approximately 1/2n), where n is refractive index of the chalcogenide (n=2.0). The ${\eta}$ is largely enhanced by Ag photodoping into the chalcogenides. In particular, the value of hmax in a bilayer of 10-nm-thick Ag/150-nm-thick AsGeSeS film is about 1.6%, which corresponds to ~20 times in comparison with that of the AsGeSeS film (without Ag).

• Mycobiology
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• v.37 no.4
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• pp.277-285
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• 2009

In this study, dual culture, poison agar, and direct methods were used to assess the ability of Trichoderma virens IMI-392430, T. pseudokoningii IMI-392431, T. harzianum IMI-392432, T. harzianum IMI-392433, and T. harzianum IMI-392434 to control Ceratocystis paradoxa, which causes the pineapple disease of sugarcane. The highest percentage inhibition of radial growth (PIRG) values were observed with T. harzianum IMI-392432 using two dual culture methods, 63.80% in Method I and 80.82% in Method II. The minimum colony overgrowth time was observed with T. harzianum IMI-392432 and the maximum was observed with T. pseudokoningii IMI-392431. Different concentrations of different day-old metabolites of Trichoderma isolates were tested against mycelial growth of C. paradoxa. The highest PIRG (84.685%) exhibited at 80% concentration of 30-day-old metabolites of T. harzianum IMI-392432 using the modified bilayer poison agar method. In the direct assay method the maximum mycelial growth weight (PIGW) was observed at the same concentration and the same day-old metabolites of T. harzianum IMI-392432. This study showed that Trichoderma isolates have a good antagonistic effect on C. paradoxa mycelial growth and T. harzianum IMI-392432 has the most potential to control the pineapple disease pathogen.

• Bulletin of the Korean Chemical Society
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• v.7 no.1
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• pp.78-81
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• 1986

The photosensitized lysis of egg lecithin lipid membranes (liposomes) have been performed to UV-B light (270-320 nm) by L-tryptophan(L-Trp) and its peptide such as N-acetylphenylalanyl-L-tryptophan(NAPT) incorporated in the liposomes(ca. 0.1% by weight) or in the external buffer (0.1-0.3 mM). Requirement of oxygenation suggests that the lysis of liposomes is caused by the photosensitized oxidation of lipids. There was significant protection against lysis photosensitized by Trp in the external buffer by low concentration of ferricyanide (0.8 mM), but there was no effect on the lytic efficiency by $N_3^-$ which is singlet oxygen($^1O_2$) quencher, indicative of an electron transfer mechanism involved in the photosensitization. The small change of the lytic efficiency with increasing pH from 4 to 9 was interpreted by large target theory and subsequently indicates that superoxide($O_2^-$) may be an active intermediate for the oxidation. The efficiency of photosensitization of Trp was higher than that of NAPT under the same experimental condition. The weak lytic efficiency of liposomes photosensitized by NAPT was enhanced by incorporating NAPT in liposomes, but it was again quenched by ${\beta}$-carotene incorporated in the bilayer of liposomes. These results indicate that a portion of liposome lysis may be due to $^1O_2$ formation from the excited NAPT.

• Bulletin of the Korean Chemical Society
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• v.18 no.7
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• pp.761-766
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• 1997

Phospholipase C from Clostridium perfringens is known to catalyze the hydrolysis of phospholipids in biological membranes. In this study, a simple and sensitive method for assaying phospholipase C was developed by using liposomes entrapping calcein as a fluorescent marker. Phospholipase C-induced lysis of liposomes was determined by measuring the fluorescence intensity of calcein released out from liposomes, Various liposomes with different compositions were prepared by reverse-phase evaporation method to investigate the effect of liposomal composition on the lytic activity of phospholipase C. The calcein-entrapping efficiency of liposomes was affected by the chain length of fatty acid in phosphatidylcholine constituting liposomes. The lytic activity of phospholipase C was the highest against liposomes prepared with eggPC. The lytic activity decreased with increasing chain length of fatty acid in phosphatidylcholine. Incorporation of cholesterol more than 20% into the liposomal bilayer inhibited the phospholipase C-induced lysis. The lysis of liposomes was more greatly increased by the addition of 10 mM of calcium. The lytic activity of phospholipase C was also affected by the surface charge of liposomes. Taken together, it was concluded that reverse-phase evaporation vesicles composed of dipalmitoylphosphatidylcholine and cholesterol in the molar ratio of 9 : 1 allowed to detect the lowest concentration of phospholipase C (0.10 μg/assay volume). This study suggested that the use of liposomes can provide a simple, sensitive and inexpensive method for assaying phospholipase C.

• Archives of Pharmacal Research
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• v.15 no.2
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• pp.152-161
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• 1992

Selective quenching of 1, 6-diphenyl-1, 3, 5-hexatriene (DPH) by trinitrophenyl groups was utilized to examine the transbilayer fluidity asymmetry of model membranes of phospholipids (SPMVPL) extracted from synaptosomal plasma membrane vesicles (SPMV). The polarization (P), anisotropy (r), limiting anisotropy $(r_\infty$), and order parameter (S) of DPH in the inner monolayer were 0.019, 0.014, 0.018, and 0.047, respectively, greater than calculated for the outer monolayer of SPMVPL. Selective quenching of DPH by trinitrophenyl groups was also utilized to examine the effects of n-alkanols on the individual monolayer structure of SPMVPL. n-Alkanols fluidized the hydrocarbon region of bulk SPMVPL and the potencies of n-alkanols up to 1-nonanon increased with carbon chain length. It appears that the potencies in bilayer fluidization increase by 1 order of magnitude as the carbon chain length increases by two carbon atoms. The cut-off phenomenon was reached at 1-decanol, where further increase in hydrocarbon length resulted in a decrease in pharmacological activity. The n-alkanols had greater fluidizing effects on the outer monolayer as compared to the inner monolayer of SPMVPL, even though these selective effects tended to become weaker as the carbon chain length increased. Thus, it has been proven that n-alkanols exhibit selective rather than nonselective fludizing effects within transbilayer domains of SPMVPL.

• Nano
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• v.13 no.11
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• pp.1850135.1-1850135.8
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• 2018

A one-step high-temperature solvothermal approach to the synthesis of monolayer or bilayer $MoS_2$ anchored onto reduced graphene oxide (RGO) sheet (denoted as $MoS_2/RGO$) is described. It was found that single-layered or double-layered $MoS_2$ were synthesized directly without an extra exfoliation step and well dispersed on the surface of crumpled RGO sheets with random orientation. The prepared $MoS_2/RGO$ composites delivered a high reversible capacity of $900mAhg^{-1}$ after 200 cycles at a current density of $200mAg^{-1}$ as well as good rate capability as anode active material for lithium ion batteries. This one-step high-temperature hydrothermal strategy provides a simple, cost-effective and eco-friendly way to the fabrication of exfoliated $MoS_2$ layers deposited onto RGO sheets.

• Korean Journal of Materials Research
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• v.30 no.12
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• pp.701-708
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• 2020

Irradiation of the metal nanoparticles causes local plasmon resonance in a specific wavelength band, which can improve the absorption and scattering properties of a structure. Since noble metal nanoparticles have better resonance effects than those of other metals, it is easy to identify plasmonic reactions and this is advantageous to find the optical tendency. Compared to having a particle gap or randomly arranged particle structures, densely and evenly packed structures can exhibit more uniform optical properties. Using the uniform properties, the structure can be applied to optical filtering applications. Therefore, in this paper, validation tests about metal nanoparticles and thin film structures are conducted for more accurate analysis. The optical properties of monolayer and bilayer noble metal nanoparticle structures with different diameters, packed in a uniform array, are investigated and their optical trends are analyzed. In addition, a thin film structure under identical conditions as metal nanoparticle structure is evaluated to confirm the improved optical characteristics.

• Progress in Superconductivity and Cryogenics
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• v.23 no.2
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• pp.14-18
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• 2021

We investigated the structural suitability of GdFeO₃ (GdFO) as a buffer layer for the GdBa₂xCu₃O_7-x (GdBCO) superconducting films. GdFO films with different thicknesses and GdBCO thin films were all prepared by using a pulsed laser deposition technique. The analyses of X-ray diffraction and EXAFS data indicates that the c-axis parameter increases and the Fe-O bond length decreases with the GdFO thickness due to the compressive stain induced by the lattice mismatch between GdFO and STO substrate and as a result, the Debye-Waller factor, an index of disorder in the local structure near the Fe-O bond, increases with the GdFO thickness. However, for the GdBCO/GdFO bilayer structure, the Debye-Waller factor decreases as the GdFO thickness increases indicating a diminished disorder by the structural coupling between GdFO and GdBCO. These results indicate that an appropriate thickness of GdFO is required to be utilized as a magnetic buffer layer for the GdBCO superconducting films.

• BMB Reports
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• v.54 no.3
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• pp.157-163
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• 2021

The transient interactions between cellular components, particularly on membrane surfaces, are critical in the proper function of many biochemical reactions. For example, many signaling pathways involve dimerization, oligomerization, or other types of clustering of signaling proteins as a key step in the signaling cascade. However, it is often experimentally challenging to directly observe and characterize the molecular mechanisms such interactions-the greatest difficulty lies in the fact that living cells have an unknown number of background processes that may or may not participate in the molecular process of interest, and as a consequence, it is usually impossible to definitively correlate an observation to a well-defined cellular mechanism. One of the experimental methods that can quantitatively capture these interactions is through membrane reconstitution, whereby a lipid bilayer is fabricated to mimic the membrane environment, and the biological components of interest are systematically introduced, without unknown background processes. This configuration allows the extensive use of fluorescence techniques, particularly fluorescence fluctuation spectroscopy and single-molecule fluorescence microscopy. In this review, we describe how the equilibrium diffusion of two proteins, K-Ras4B and the PH domain of Bruton's tyrosine kinase (Btk), on fluid lipid membranes can be used to determine the kinetics of homodimerization reactions.