• Journal of Environmental Science International
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• v.11 no.2
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• pp.131-137
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• 2002

The chemical behavior and properties on the redox state of environmental pollutant has been investigated by electrochemical methods. We carried out to measure the variations in the redox reaction of differential pulse polarogram and cyclic voltammogram. The results observed the influences on redox potential and current of various factors with temperature and pH. These were established factors as the effect of the redox reaction. It can be clearly recognized that the electrode reaction are from qusi-reversible to irreversible processes. Also, it was mixing with reaction current controlled. The bits-phenol A in the waste water was made to compound with cobalt ion and it take away from the separation into compound. The $Co(BPA)_2$ compound was not found to be dissociation in waste water. However, this compound is avery unstable(K=1.02) and for a while, it was to be a dissociation. Therefore, we believed that it was likely to a toxic substance.

• Journal of Embryo Transfer
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• v.30 no.1
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• pp.17-21
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• 2015

Alteration in ion channel or transporter expression levels affects cell volume which is produced by movement of water and ion across the plasma membrane. In particular, aquaporin (AQP) channels among ion channels play a crucial role in movement of water across the cell membrane. This study was performed to identify whether AQP expression is changed in bovine follicular cystic follicles using microarray, RT-PCR and Western blotting analyses. In microarray data, AQP4 expression was decreased, whereas AQP7 was increased in cystic follicles. Additional experiments were focused on the AQP7 expression increased in cystic follicles. The microarray data was confirmed by semi-quantitative polymerase chain reaction (PCR) and Western blot analysis. AQP7 mRNA and protein expressions were significantly increased in the cystic follicles (p<0.05). Application of estrogen ($10{\mu}g/ml$) to bovine ovarian cells showed a trend of increase in AQP7 expression. From these results, we suggest that the increase in AQP7 expression in cystic follicles may play an important role in movement of water in bovine ovary. In addition, AQP7, a aquaglyceroporin permeating water and glycerol, could be a good target in development of methods for the cryopreservation of bovine ovary.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06a
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• pp.5-18
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• 1996

The solid state cesium ion source os alumino-silicate based zeolite which contains cerium. The material is an ionic conductor. Cesiums are stably stored in the material and one can extract the cesiums by applying electric field across the electrolyte. Cesium ion bombardment has the unique property of producing high negative ion yield. This ion source is used as the primary source for the production of a negative ion without any gas discharge or the need for a carrier gas. The deposition of materials as an ionic species in the energy range of 1.0 to 300eV is recently recognized as a very promising new thin film technique. This energetic non-thermal equilibrium deposition process produces films by “Kinetic Bonding / Energetic Condensation" mechansim not governed by the common place thermo-mechanical reaction. Under these highly non-equilibrium conditions meta-stable materials are realized and the negative ion is considered to be an optimum paeticle or tool for the purpose. This process differs fundamentally from the conventional ion beam assisted deposition (IBAD) technique such that the ion beam energy transfer to the deposition process is directly coupled the process. Since cesium ion beam sputter deposition process is forming materials with high kinetic energy of metal ion beams, the process provider following unique advantages:(1) to synthesize non thermal-equilibrium materials, (2) to form materials at lower processing temperature than used for conventional chemical of physical vapor deposition, (3) to deposit very uniform, dense, and good adhesive films (4) to make higher doposition rate, (5) to control the ion flux and ion energy independently. Solid state cesium ion beam sputter deposition system has been developed. This source is capable of producing variety of metal ion beams such as C, Si, W, Ta, Mo, Al, Au, Ag, Cr etc. Using this deposition system, several researches have been performed. (1) To produce superior quality amorphous diamond films (2) to produce carbon nitirde hard coatings(Carbon nitride is a new material whose hardness is comparable to the diamond and also has a very high thermal stability.) (3) to produce cesiated amorphous diamond thin film coated Si surface exhibiting negative electron affinity characteristics. In this presentation, the principles of solid state cesium ion beam sputter deposition and several applications of negative metal ion source will be introduced.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.272-272
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• 2013

The attractive features of photosynthetic reaction center proteins for energy application make them useful in solar energy conversion to hydrogen fuel or electrical energy. Almost unity charge separation quantum yield and its rapid speed of ~1ns, absorbance region in visible light (480~740 nm) and high proportion of photosynthetically active solar energy of 48.5% allowed photosystem1 to exploited as a bio-material for photo-energy devices. Directionality of photosystem1 in electron transfer can solve main problem in two-step water splitting process where back reaction deteriorates the overall efficiency. In the study, photosystem1 was extracted from spinach and the photo-induced excited electron in the reaction center was utilized in various field of light energy application. First, hydrogen evolving system realized by photodeposition of platinum at the end of the electron transfer chain, with combining specific semiconductor to oxidize water in the first step of Z-scheme. The evaluation by gas-chromatography demonstrated hydrogen evolution through the system. For the further application of photoelectrical material on electrode, photosystem1 have been controlled by copper ion, which is expected to assemble photosystem in specific orientation followed by maximized photoelectrical ability of film. The research proposed concrete methods for combining natural protein and artificial materials in one system and suggested possibility of designing interface between biological and inorganic materials.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.7 no.2
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• pp.141-146
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• 2021

With increasing interest in fluorinated compounds, nucleophilic fluorination reaction has been generally used for synthesizing fluorine-containing chemicals. However, alkali metal fluorides (MFs) generally have low solubility and reactivity in organic solvent. To overcome these problems, various phase transfer catalysts (PTCs) have been investigated. Calix-arene is known as to capture the metal cation(M⁺), and therefore in this review, we would like to introduce several kinds of calix-arene based PTCs, such as bis-tert-alcohol-functionalized crown-6-calix[4]arene (BACCA), oligo-ethylene glycol linked bis-triethyleneglycol crown-5-calix[4]arene (BTC5A), and ionic liquid functionalized calix-arene based catalyst, as well as ion-pair receptor crown-6-calix[4]arene-capped calix[4]pyrrole.

• Journal of the Korean Chemical Society
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• v.38 no.10
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• pp.705-709
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• 1994

The kinetics of the oxidation reaction of malonic acid by ceric ion in 1 M sulfuric acid solution at $20^{\circ}C$ have been investigated by spectrophotometric method. The reaction rate at a large excess of malonic acid was found to be pseudo-first order. The observed pseudo-first order rate constants, $k_{obs}$, are dependent on the concentration of malonic acid, [MA], of which relationship has been found to be $k_{obs}$ = (0.592[MA])/(1+14.5[MA]$^2$). A mechanism for the reaction has been suggested on the basis of the above rate equation. The rate determining step may be the electron transfer reaction between enolate type malonate anion, which is formed by the acid dissociation reaction of malonic acid, and Ce(IV). The rate depression in the range of high concentration of MA has been explained by the formation of 1 : 2 chelate between Ce(IV) and malonate. According to the mechanism, the pH dependence of the rate, which was studied by Sengupta et al., has also been explained.

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.64-71
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• 1992

New type dioxygen bridged complexes of palladium were prepared by using $KO_2$ as a source of superoxide ion($O_2{^-}$). The method is completely different from the traditional one which has adopted the oxidative addition of molecular oxygen to prepare the dioxygen complexes. This reaction proceeds via nucleophilic displacement followed by electron transfer reaction. Three new type dioxygen complexes of palladium having amine ligands were prepared and characterized by the application of the reaction of $O_2{^-}$.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.581-588
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• 2018

In this article, electrochemical investigation of the transfer reaction of ionizable cefotiam (CTM), an antibiotic molecule across a polarized water/1,2-dichloroethane (water/1,2-DCE) interface was studied. Ion partition diagram providing the preferred charged form of CTM in either water or 1,2-DCE phase was established via the voltammetric evaluation of the transfer process of differently charged CTM species depending upon the pH variation of aqueous solutions. Thermodynamic information including the formal transfer potential and formal Gibbs transfer energy values in addition to important pharmacokinetics including partition coefficients of ionizable CTM were also evaluated. In particular, the current associated with the transfer of CTM present at pH 3.0 aqueous solution proportionally increased with respect to the CTM concentration which was further used for developing CTM sensitive ion sensor. In order to improve the portability and convenient usage, a single microhole interface fabricated in a supportive polyethylene terephthalate film was used of which hole was filled with a polyvinylchloride-2-nitrophenyloctylether (PVC-NPOE) gel replacing 1,2-DCE, a toxic organic solvent. A dynamic range of $1-10{\mu}M$ CTM was obtained.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.506-512
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• 2017

The transfer reaction characteristics of tetracycline (TC) across a polarized water/1,2-dichloroethane (1,2-DCE) interface was studied via controlling both pH and ionic strength of the aqueous phase in conjunction with cyclic and differential pulse voltammetries. Formal transfer potential values of differently charged TC ionic species at the water/1,2-DCE interface were measured as a function of pH values of the aqueous solution, which led to establishing an ionic partition diagram for TC. As a result, we could identify which TC ionic species are more dominant in the aqueous or organic phase. Thermodynamic properties including the formal transfer potential, partition coefficient and Gibbs transfer energy of TC ionic species at the water/1,2-DCE interface were also estimated. In order to construct an electrochemical sensor for TC, a single microhole supported water/polyvinylchloride-2-nitrophenyloctylether (PVC-NPOE) gel interface was fabricated. A well-defined voltammetric response associated with the TC ion transfer process was achieved at pH 4.0 similar to that of using the water/1,2-DCE interface. Also the measured current increased proportionally with respect to the TC concentration. A $5{\mu}M$ of TC in pH 4.0 buffer solution with a dynamic range from $5{\mu}M$ to $30{\mu}M$ TC concentration could be analyzed when using differential pulse stripping voltammetry.

• Journal of the Korean Chemical Society
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• v.39 no.4
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• pp.275-280
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• 1995

The electron transfer reactions between cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2-(Y=EDTA, PDTA, CyDTA) have been investigated in the presence of hydrogen ion. From the kinetic data, it has been found that electron transfer reactions between cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2- proceed via inner-sphere pathway by catalysis of hydogen ion. The stereoselectivity in the electron transfer reactions between optically active △-cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2- produced 6.0, 2.9, 3.0% e.e.(e.e.=enantiomeric excess) of △-[Co(EDTA)]-, △-[Co(PDTA)]- and △-[Co(CyDTA)]-, respectively. Based upon this observation, it seems that △-cis-[Co(en)2(NO2)2]+ is associated with rac-[Co(Y)]2- at first, and followed by the electron transfer reaction. Therefore, it was suggested that stereoselective electron transfer reaction between △-cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2- proceed through both inner-sphere by the proton catalysis and outer-sphere with ionic association.