• Journal of the Korean Ceramic Society
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• v.29 no.8
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• pp.623-629
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• 1992

The possible use of bioglass as implant materials is due to its biocompatibility to human body. Even if many animal studies for the bioglasses have been performed, their compositional dependences of structures and physical properties are not fully understood. In the present work, physical property measurements such as density and thermal expansion coefficient were carried out for the bioglasses, with substitution of CaO for Na2O in bioglass composition (46.1%SiO2, 24.4%Na2O, 26.9%CaO, 2.6%P2O5:mol%). Hydroxyapatite formation on the glass surface was also examined after reacted in Tris-buffer solution. As CaO was substituted for Na2O, the bond strength between nonbridging oxygen and modifier became stronger to make glass structure rigid, and resulted in increase in density and decrease in thermal expansion coefficient. When the bioglasses were reacted in Tris-buffer solution, hydroxyapatite was formed on the bioglass surface for all prepared glasses in 2 hours, independently on CaO content, and the thickness of hydroxyapatite layer was decreased a little, while the thickness of SiO2 rich layer was decreased sharply with CaO content.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.93-96
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• 2001

We have reported to make nanostructured cobalt oxide electrode that have large capacitance over than 400F/g (specific capacitance) and good cycleability. But, It had serious demerits of low voltage range under 0.5V and low power density. Therefore, we need to increase voltage range of cobalt oxide electrode. we report here on the electrochemical properties of sol-gel-derived nanoparticulate cobalt xerogel in 1M KOH solution and aqueous polymeric gel electrolyte. In solution electrolyte, cobalt oxide electrode had over than 250F/g capacitance consisted of EDLC and pseudocapacitance. In gel electrolyte, cobalt oxide electrode had around 100F/g capacitance. This capacitance was only surface EDLC. In solution electrolyte, potassium ion as working ion reacted with both of layers easily. However, In gel electrolyte, reacted with only surface-active layer. Its very hard to reach resistive layer. So, e have studied on pretretmetn of electrode to contain working ions easily. We'll report more details.

• Journal of the Mineralogical Society of Korea
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• v.9 no.2
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• pp.71-81
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• 1996

Dissolution experiments were conducted to understand chemical nature of weathering of anorthosite from the Hadong area. Anorthosite and plagioclase from it were reacted with HCl or KOH solutions under various conditions concerning such as grain size, initial pH of solutions, and shaking Average composition of plagioclase used in the experiment was Na0.32Ca0.71Al1.71Si2.28O8.Under acidic conditions, solution pH increases rapidly in the initial stage and then gradually to reach palteau. Shaking agitates the reaction rate in the initial stage but does not affect after the system reached steady state. Ca and si concentrations show rapid increase and then gradual increase. Al concentration increases rapidly in the early stage and then decreases. Later decrease was interpreted as the precipitation of an Al-bearing material. Different dissolution rates of different constituents of plagioclase together the with precipitation of al-bearing material might be responsible for the non-stoichiometric dissolution of plagioclase.X-ray diffraction analyses on anorthosite before and after dissolution experiment show dissolution rates differ with different lattice planes of plagioclase. It suggests the crystallographic control on dissolution reaction. X-ray photoelectron spectroscopic result shows that the average composition of plagioclase surface reacted with HCL of initial pH 1.97 for 2000 hours is Na0.20Ca0.26Al1.7Si2.3O8. It means that Na- and Ca-depleted H-feldspar is developed without Al-depleted layer on the surface of plagioclase by reaction with HCl and that dissolution reaction takes place sparsely on the surface of plagioclase. Al and Si are dissolved preferentially over Ca from anorthosite powder in KHO solution. Reaction of acid-reacted anorthosite with KOH solution shows the same Si dissolution behavior as in the fresh anorthosite. This indicates that the Al-depleted and Si-enriched layer does not build up on the acid-reacted surface.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.250-250
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• 2003

• Journal of Applied Biological Chemistry
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• v.58 no.1
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• pp.9-11
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• 2015

Tissue extracts were prepared from liquid-cultured Arabidopsis and reacted with UDP-[$^3H$]-GlcNAc. Phospholipid fractions were then extracted by butanol partitioning. Consecutive thin-layer chromatography identified two glycolipids sensitive to PI-specific phospholipase C, known as early intermediates in glycosylphosphatidylinositol anchor biosynthesis; phosphatidylinositol N-acetylglucosamine and phosphatidylinositol glucosamine.

• Applied Microscopy
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• v.32 no.3
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• pp.247-255
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• 2002

In this study, we carried out immunostaining and immunogold labeling with antibodies to serotonin and somatostatin to examine the characteristics and functions of the neurons that secrete neurotransmitters in optic lobes of Todarodes pacificus and Octopus minor. As a result of immunostaining with anti-somatostatin, the nerve cells of Todarodes pacificus reacted as similar to the anti-serotonin, but in Octopus minor, only large cells in the outer granule cell layer reacted positively. In the immunogold labeling with anti-serotonin, the nerve cells in the inner grande cell layer and medulla of Todarodes pacificus reacted strongly, 30 gold particles being labeled per $0.5{\mu}m^2$ of the cytoplasm. However, in Octopus minor, only 17 gold particles were labeled, which stated a weak reaction. On the other hand, in the anti-somatostatin case, the nerve cells in the outer and inner granule cell layers and medulla of Todarodes pacificus showed strong reaction, 30 gold particles being labeled per $0.5{\mu}m^2$ of the cytoplasm while the nerve cells in the outer granule cell layer of Octopus minor reacted weakly, about 3 gold particles being labeled per the equivalent area. As a result of immunostaining and immunogold labeling with two types of antibodies to each part of the optic lobes, we found that the reactive nerve cells were distributed differently in the two species. In particular, the degree of reactivity to the immunostaining and immunogold labeling appeared stronger in Todarodes pacificus than in Octopus minor.

• Bulletin of the Korean Chemical Society
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• v.24 no.8
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• pp.1197-1202
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• 2003

Patterning of biological molecules was attempted on both gold and glass using fourth generation (G4) poly(amidoamine) (PAMAM) dendrimer as an interfacing layer between solid surfaces and biomolecules. As for the patterning of avidin and anti-biotin antibody on gold, PAMAM dendrimers representing amine functionalities were firstly printed onto the 11-mercaptoundecanoic acid SAM by microcontact printing, followed by biotinylation, and reacted with fluorescence-labeled avidin or anti-biotin antibody. Fluorescence microscopic analysis revealed that the patterns of avidin and anti-biotin antibody were well constructed with the resolution of < 2 ㎛. The PAMAM dendrimers were also printed onto aldehyde-activated slide glass and reacted directly with anti-BSA antibodies, which had been oxidized with sodium periodate. As a result, distinct patterns of the anti-BSA antibodies were also obtained with a comparable edge resolution to that of avidin patterns on gold. These results clearly show that PAMAM dendrimers can be adopted as an interfacing layer for the patterning of biological molecules on solid surfaces with micrometer resolution.

• Journal of the Korean Ceramic Society
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• v.27 no.8
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• pp.979-990
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• 1990

The possible use of bioglass as implant materials is due to its biocompatibility to human body. Even if many animal studies for the bioglasses have been performed, their structures and physical properties are not fully understood. In the present work, several investigations such as Raman spectroscopic analysis, density, thermal expansion coefficient, softening temperature, and refractive index measurement were carried out to find the structures and physical properties of bioglasses, where MgO is substituted for CaO in bioglass composition (46.1%SiO2, 24.4%Na2O, 26.9%CaO, 2.6%P2O5 ; mole%). Hydroxyapatite formation on the glass surface reacted in Tris-buffer solution was also examined. When CaO was replaced by MgO, nonbridging oxygen in glass structuer was diminished but the degree of disorder increased. Thermal expansion and softening properties showed the mixed oxide effect. Hydroxyapatite were formed on the surface of 0~11mole% of MgO containing bioglasses, and the thickness of SiO2-rich layer as well as hydroxyapatite layer were unchanged with MgO content. However, the hydroxyapatite was not formed on the surface of the bioglasses containing over 11 mole percent MgO, even if the glasses were reacted for long period.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.628-631
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• 2002

$Al_2O_3$ capping layer and MgO protective layer were deposited by electron beam evaporation method using single crystal source. Thickness of the capping layer, $Al_2O_3$, was varied from 5 nm to 10 nm. Surface morphology was observed by SEM and AFM before and after hydration. And microstructure of deposited $Al_2O_3$ layer and chemical shift of electron binding energy were also observed by high resolution TEM and XPS, respectively, after hydration. From these results, it was found that Mg atoms diffused into $Al_2O_3$ layer, reacted with moisture and formed $Mg(OH)_2$ during hydration. As thickness of $Al_2O_3$ increased, extent of hydration increased. $Al_2O_3$ capped MgO thin films and uncapped MgO thin films were deposited on AC-PDP test panel to characterize discharge properties. Although $Al_2O_3$ has poor discharge properties rather than MgO, because of many hydrated species on the surface of MgO, similar discharge properties were observed.

• Korean Journal of Materials Research
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• v.26 no.12
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• pp.751-756
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• 2016

Graphite was diffusion-bonded by hot-pressing to W-25Re alloy using a Ti interlayer. For the joining, a uniaxial pressure of 25 MPa was applied at $1600^{\circ}C$ for 2 hrs in an argon atmosphere with a heating rate of $10^{\circ}C\;min^{-1}$. The interfacial microstructure and elemental distribution of the W-25Re/Ti/Graphite joints were analyzed by scanning electron microscopy (SEM). Hot-pressed joints appeared to form a stable interlayer without any micro-cracking, pores, or defects. To investigate the high-temperature stability of the W-25Re/Ti/Graphite joint, an oxy-acetylene torch test was conducted for 30 seconds with oxygen and acetylene at a 1.3:1 ratio. Cross-sectional analysis of the joint was performed to compare the thickness of the oxide layer and its chemical composition. The thickness of W-25Re changed from 250 to $20{\mu}m$. In the elemental analysis, a high fraction of rhenium was detected at the surface oxidation layer of W-25Re, while the W-25Re matrix was found to maintain the initial weight ratio. Tungsten was first reacted with oxygen at a torch temperature over $2500^{\circ}C$ to form a tungsten oxide layer on the surface of W-25Re. Then, the remaining rhenium was subsequently reacted with oxygen to form rhenium oxide. The interfacial microstructure of the Ti-containing interlayer was stable after the torch test at a temperature over $2500^{\circ}C$.