• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.881-884
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• 2012

We report a quantum chemical study of an extremely efficient nucleophilic aromatic fluorination in molten salts. We describe that the mechanism involves solvent anion interacting with the ion pair nucleophile $M^+F^-$(M = Na, K, Rb, Cs) to accelerate the reaction. We show that our proposed mechanism may well explain the excellent efficiency of molten salts for SNAr reactions, the relative efficacy of the metal cations, and also the observed large difference in rate constants in two molten salts $(n-C_4H_9)_4N^+\;CX_3SO_3^-$, (X=H, F) with slightly different sidechain ($-CH_3$ vs. $-CF_3$).

• Radiation Oncology Journal
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• v.33 no.2
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• pp.66-74
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• 2015

Trace elements play crucial role in the maintenance of genome stability in the cells. Many endogenous defense enzymes are containing trace elements such as superoxide dismutase and metalloproteins. These enzymes are contributing in the detoxification of reactive oxidative species (ROS) induced by ionizing radiation in the cells. Zinc, copper, manganese, and selenium are main trace elements that have protective roles against radiation-induced DNA damages. Trace elements in the free salt forms have protective effect against cell toxicity induced by oxidative stress, metal-complex are more active in the attenuation of ROS particularly through superoxide dismutase mimetic activity. Manganese-complexes in protection of normal cell against radiation without any protective effect on cancer cells are more interesting compounds in this topic. The aim of this paper to review the role of trace elements in protection cells against genotoxicity and side effects induced by ionizing radiation.

• Journal of Powder Materials
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• v.13 no.5 s.58
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• pp.336-339
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• 2006

Magnetic properties of nanostructured materials are affected in complicated manner by their microstructure such as pain size (or particle size), internal strain and crystal structure. Thus, studies on the synthesis of nanostructured materials with controlled microstructure are necessary fur a significant improvement in magnetic properties. In the present work, nanostructured Fe-Co alloy powders with a grain size of 50 nm were successfully fabricated from the powder mixtures of (99.9% purity) $FeCl_2$ and $CoCl_2$ by chemical solution mixing and hydrogen reduction.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.11 no.1
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• pp.32-55
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• 1975

The ammonium salt of N-Nitrosophenylhydroxiamine, namely Cupferron, is a well-known analytical reagent which precipitates a great number of metal ions in acid medium. Various structures of electrode reduction for N-Nitrosophenylhydroxiamine have been suggested in acid and alkaline media by many researchers, but not in neutral medium. So the mechanism of electrode reaction of Cupferron was investigated by both chronopotentiometric and polarographic methods. It was estimated that the reduction of Cupferron occurs in a three-step mechanism through which a chemical step is interposed between two charge transfer, the ECE (charge transfer-chemical reaction-charge transfer) mechanism, over a range of neutral and alkaline media. The chemical reaction of the process was assumed to be acid-base catalyzed from the fact that kapp (over all rate constant) of chemical reaction is pH dependent.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.06a
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• pp.65-70
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• 1998

The Spray-ICP technique uses the ICP(Inductively Coupled Plasma) of ultra-high temperature which is produced by r.f power. The ICP is well-kwown as a clean heat source for the preparation of pure ceramic particles because the ICP is a electrodeless-thermal plasma without contamination. In this study,{{{{ { SnO}_{2 } }}}} particles were sythesized from metal salt solution by Spray-ICP technique. The effects of concentration of solution, collecting location of powders were investicated. The prepared {{{{ { SnO}_{2 } }}}} particles from each concentration of solution had same crystalline phase(tetragonal {{{{ { SnO}_{2 } }}}}) a nd the mean size decreased in proportion to the increase of solution concentration. Each {{{{ { SnO}_{2 } }}}} p owders collector in reactor and electrostatic collector had same crystalline phase and morphologies. The mean size of {{{{ { SnO}_{2 } }}}} p articles prepared by Spray-ICP technique was below 30nm.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.707-708
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• 2000

Colloidal gold with a conducting polymer (e.g., polyaniline) bound on the metal surfaces has been used for the generation of conductimetric signal in a membrane strip immunosensor. Since polyaniline itself at a low pH range revealed a low conductivity, an approach of doping the polymer with a lithium salt was used. As an alternative method, a self-doped (i.e., pH-independent) sustance such as leucoemeraldine base sulfonated polyaniline (LEB-SPAN) can be used as signal generator. It was also highly soluble in water and, thus, such a selected polymer was expected to support a satisfactory property as a label of the immunosensor.

• Journal of the Korean Ceramic Society
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• v.24 no.6
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• pp.593-601
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• 1987

A thermodynamic model to predict the stability of the water-in-oil type emulsion and the size of the droplets in stable emulsions was developed. Using this model, the effects of various factors government the droplet size in the metal salt solution-kerosene-span 80 system for the preparation of Al2O3-ZrO2 composite powders were investigated. It was shown that the given emulsion systems were thermodynamically unstable in every case but could be kinetically meta stable. When radius ofthe droplet was below nm, the increase in entropy change due to the configurational contribution of small droplets dominated the total free energy change for emulsification. The optimum conditions under which smaller deoplet was obtained were proposed and the validity of the model was proved with diameters of the droplet and composite powders experimentally determined.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.3
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• pp.301-308
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• 2007

Silicate mineral serpentine with magnesium and calcium was selected as a mineral carbonation mediators for carbon dioxide storage. Serpentine has various metallic elements as an oxides form of magnesium, iron, calcium, aluminium etc. Magnesium and calcium could be carbonation salt preferentially than other metal component within serpentine. Systemic thermochemical treatment for serpentine could change physicochemical properties like a surface area and pore dimensions. Due to the rapid chemical reaction rate depended on dimensional values, carbonation formation could determined by surface property change of thermochemical treated serpentine.

• YAKHAK HOEJI
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• v.38 no.4
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• pp.418-424
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• 1994

Lectin from mistletoe (Viscum coloratum) were obtained by salt fractionation, gel filtration and anion exchange chromatography. A molecular weight of about 60,000D has been determined by SDS-PAGE and two basic subunits which have molecular weights of 33,000D and 28,000D are linked by a disulfide bond. The partially purified mistletoe lectins agglutinated human B erythrocytes. Agglutinating activity was relatively stable at varied pH $(3.77{\sim}8.71)$ and at temperature range of $0{\sim}40^{\circ}C$ and not affected by 9 metal ions. Galactose, lactose and N-acetyl-D- galactosamine inhibited agglutinating activity of lectin. Lectin from mistletoe was more mitogenic to murine lymphocytes than concanavalin A.

• Journal of the Korean Ceramic Society
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• v.25 no.3
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• pp.284-292
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• 1988

Alumina-zirconia composite powders for the purpose of improving fracture toughness and thermal shock resistance of alumina were prepared by the emulsion-kerosene drying method. The average particle size of composite powders was less then 1 $\mu\textrm{m}$ and their shapes were spherical. It was shown that the average particle size of composite powders decreased with the concentration of metal-salt in solution and the amount of span 80 added when preparing emulsions. The structure of all zirconia in composite powders heat-treated at 1200$^{\circ}C$ was a tetragonal form at room temperature. This result implied that fine zirconia particles were homogeneously dispersed in the alumina matrix.