• Journal of the Korean Chemical Society
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• 제31권5호
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• pp.444-451
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• 1987

The dependence of polarographic parameters on the pressure for the reduction of copper(II), cadmium(II), and zinc(II) complex ions with ethylenediamine, propylenediamine, and diethylenetriamine has been studied. In this study the dropping mercury electrode, the mercury pool electrode, and helix type of platinum wire were used as the working, the reference, and the auxilary electrode, respectively. With increasing the pressure from 1 atmosphere to 1,500 atmospheres, the reduction half-wave potentials of metal complex ions are shifted to the negative values and the diffusion currents become considerably larger, in keeping with the theory on the change of the physical properties of the electrolytic solution such as the density, the viscosity, the dielectric constant, and the electrical conductance, etc. The slope values of the logarithmic plot are increased with increasing the pressure, which indicates the more irreversible reduction. The temperature coefficients of diffusion current observed over the range of the temperature from 25$^{\circ}$C to 35$^{\circ}$C are about two percentage with increasing the pressure, therefore the polarographic reduction under the high pressure is controlled by diffusion. The linear relationships between diffusion current and concentration of metal complex ions are established over all pressure range.

• Carbon letters
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• 제6권3호
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• pp.158-165
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• 2005

Room temperature kinetics of degradation of nerve agent simulants and sarin, an actual nerve agent at the surface of different carbon based adsorbent materials such as active carbon grade 80 CTC, modified whetlerite containing 2.0 and 4.0 % NaOH, active carbon with 4.0 % NaOH, active carbon with 10.0 % Cu (II) ethylenediamine and active carbon with 10.0 % Cu (II) 1,1,1,5,5,5-hexafluoroacetylacetonate were studied. The used adsorbent materials were characterized for surface area and micropore volume by $N_2$ BET. For degradation studies solution of simulants of nerve agent such as dimethyl methylphosphonate (DMMP), diethyl chlorophosphate (DEClP), diethyl cyanophosphate (DECnP) and nerve agent, i.e., sarin in chloroform were prepared and used for the uniform adsorption on the adsorbent systems using their incipient volume at room temperature. Degradation kinetics was monitored by GC/FID and was found to be following pseudo first order reaction. Kinetics parameters such as rate constant and half life were calculated. Half life of degradation with modified whetlerite (MWh/NaOH) system having 4.0 % NaOH was found to be 1.5, 7.9, 1206 and 20 minutes for DECnP, DEClP, DMMP and sarin respectively. MWh/NaOH system showed maximum degradation of simulants of nerve agents and sarin to their hydrolysis products. The reaction products were characterized using NMR technique. MWh/NaOH adsorbent was also found to be active against sulphur mustard.

• Korean Journal of Microbiology
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• 제50권1호
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• pp.22-26
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• 2014

Protocatechualdehyde (PA) is phenolic compound having antioxidative and antitumor activities. PA was purified from supernatant of Streptomyces lincolnensis M-20. In the presence of copper ion, PA acted as pro-oxidant. The antioxidant activity was assessed with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, and the pro-oxidant effect of PA on DNA damage as pBR322 plasmid DNA-cleaving agents in the presence of Cu(II) ions was investigated. The involvement of reactive oxygen species (ROS) in the DNA damage was confirmed by the inhibition of the DNA breakage by using glutathione (GSH), specific scavenger of ROS. When the increase in ROS reaches a certain level (the toxic threshold), it may trigger cell death. The formation of the PA/Cu(II) chelate complex was confirmed by reaction with ethylenediamine-tetraacetic acid (EDTA), a well-known chelating agent for metal ions, by using UV/Vis spectroscopic analysis.

• Korean Journal of Animal Reproduction
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• 제18권4호
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• pp.285-297
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• 1995

The mammalian oviduct is a place where ontogeny of an animal begins. Nowadays, however, it is possilbe to manipulate a part of physiological events occurring in the oviduct so that fertilization of gametes and early embryonic development of zygotes could proceed outside oviductal environment. Rabbit zygotes readily develop to blastocysts in a conventional culture condition. Most of the mouse fertilized eggs do so when cultured under a specific environment, e.g., in a medium containing ethylenediamine tetraacetic acid. Similarly, a significant number of zygotes from rat, sheep, pig or cattle can develop to blastocysts if they are cultured in the presence of particular component which appear to be somewhat species-specific. Instead of changing the components of medium, somatic cells including oviductal epithelial cells, have widely been used to improve mammalian embryonic development in vitro. Many investigators have reported that mammalian zygotes, whether fertilized in vivo or in vitro, could develop to blastocysts when they were cultured on a monolayer of various kinds of somatic cells or even in a somatic cell-conditioned medium. While little is known about the nature of embryotrophic factor(s) produced in vitro by somatic cells, the existence fo oviduct-specific protein(s) has consistently been demonstrated in many laboratories. Some of these proteins are reported to be associated with oviductal eggs. However, the physiological role of these proteins has still to be determined. Recently we observed that the perivitelline space of mouse oocytes was fluorescently stained with various fluorochrome-protein conjugates following ovulation into the oviducts or upon their expossure to oviductal extracts. Furthermore, it was also found that cattle or pig oviductal fluid gave similar results when examined using mouse ghost ZP. These observations lead to suggest that mammalian oviduct induces changes of biochemical properties of oocytes. Further studies are needed to clarify the nature of oviductal factor(s) and the physiological meaning of the reaction.

• Korean Journal of Food Science and Technology
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• 제25권5호
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• pp.517-520
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• 1993

As the pH of ground pork increased from 5.0 to 7.0, the corresponding development of 2-thiobarbituric acid reactive substance (TBARS) during storage at $4^{\circ}C$ decreased significantly (p<.001). At the 4th day of refrigerated storage, with the increase in pH of ground pork from 5.0 to 7.0, the release of free iron decreased significantly (p<.05) from 1.50 to .99 ppm. The decrease in free iron content of pH 7 pork well explains the decrease in TBARS absorbances. The fact that the addition of 2% ethylenediamine tetraacetic acid (EDTA) to pH 5 ground pork decreased the oxidative rancidity development (p<.001) strongly supported the above finding that the increased free iron content of pH 5ground pork catalyze the oxidation during storage. The activity of glutathione peroxidase (GPx) at the 4th day of refrigerated storage decreased significantly (p<.05) when the pH of ground pork decreased from 7.0 to 5.0. Both the lower free iron content and the higher activity of GPx were proved to be important factors in controlling the oxidative rancidity of high pH ground pork.

• Korean Journal of Food Science and Technology
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• 제44권2호
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• pp.191-195
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• 2012

Aminated gelatin microparticles were prepared with fucoidan at concentrations ranging from 0.5 to 2.0%. In order to acquire a higher primary amino group content regarding gelatin, gelatin was synthesized by using 1,2-ethylenediamine and free amino groups of aminated gelatin microsphere sample uncrosslinked or crosslinked with fucoidan have been determined by using trinitrobenzensulfonic acid (TNBS) methods. At the smallest fucoidan concentration, the free amino group content of the aminated gelatin microparticles was highest and decreased when fucoidan concentrations were increased. Furthermore, as concentration of fucoidan increased, the release from microparticles decreased. The $in$ $vitro$ gastric mucoadhesion of microparticles were evaluated by using fluorescent-labeled microparticles in an isolated and perfused mouse stomach. The gastric mucoadhesion of the aminated gelatin microparticles was significantly improved compared with that of gelatin microparticles.

• Journal of the Korean Chemical Society
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• 제25권6호
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• pp.394-398
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• 1981

Two types of Ni(II)-polyethyleneimine (PEI) complexes, [Ni(PEI)]$Cl_2$ and [Ni(P-EI)$Cl_2$] were synthesized and their catalytic activities in the decomposition reaction of hydrogen peroxide were investigated. For the purpose of comparison, the corresponding monomeric complexes, $[Ni(en)_3]Cl_2$ and $[Ni(en)_2Cl_2$ were also prepared; it was observed that their activities increase in the following order; $0{\approx}[Ni(en)_3]Cl_2{\le}[Ni(en)_2Cl_2]<[Ni(PEI)]Cl_2<[Ni(PEI)Cl_2]$ On the basis of structural analysis by means of visible and infrared spectroscopy, the catalytic activiy of these Ni(II)-PEI complexes is assumed to depend on the bond strength between the ligand and the nickel ion.

• Journal of the Korean Applied Science and Technology
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• 제33권1호
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• pp.23-29
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• 2016

Zinc oxide of hexagonal wurzite, is known as n-type semiconductor. It has a wide band gap energy of 3.37 eV and large exciton binding energy of 60 meV. It can be widely applied to gas sensors, laser diodes, dye-sensitized solar cells and degradation of dye waste. The use of microwave hydrothermal synthesis brings a rapid reaction rate, high yield, and energy saving. Amine additives control the different particle shapes because of the chelate effect and formation of hydroxide ion. In this study, zinc nitrate hexahydrate was used as zinc precursor. In addition, ethanolamine, ethylenediamine, diethylenetriamine, and hexamethylenetetramine are used as shape control agent. The pH value was controlled as 11 by NaOH. The shapes of zinc oxide are star-like, rod, flower-like, and circular cone. In order to analyze physical, chemical, and optical properties of ZnO with diverse amine additives, we used XRD, SEM, EDS, FT-IR, UV-Vis spectroscopy, and PL spectroscopy.

• Journal of Ecology and Environment
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• 제30권3호
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• pp.271-276
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• 2007

A simple and efficient protocol was developed for culturing Cu-tolerant and Cu-accumulating plants via pre-adaptation to Cu during plant tissue culture. We induced multiple shoots from begonia (Begonia evansiana Andr.) leaf explants on MS medium supplemented with naphtaieneacetic acid and benzyladenine. After 3 months, small plantlets were transferred to MS medium supplemented with $100{\mu}M\;CuCl_2$ for pre-adaptation to Cu and cultured for 5 months. Then, these plantlets were individually planted in pots containing artificial soil. An additional 500 mg of Cu dissolved in 1/4 strength MS solution was applied to each pot during irrigation over the course of 2 months. We planted pre-adapted and control begonias in soil from the II-Kwang Mine, an abandoned Cu mine in Pusan, Korea, to examine their ability to tolerate and accumulate Cu for phytore-mediation. Pre-adapted begonias accumulated $1,200{\mu}g$ Cu/g dry root tissue over the course of 45 days. On the other hand, non-Cu-adapted controls accumulated only $85{\mu}g$ Cu/g dry root tissue. To enhance Cu extraction, chelating agents, ethylenediamine tetraacetic acid (EDTA)-dipotassiun and pyridine-2,6-dicarboxylic acid (PDA), were applied. While the chelating agents did not enhance accumulation of Cu in the roots of control begonias, EDTA application increased the level of Cu in the roots of pre-adapted begonias twofold (to $2,500{\mu}g$ Cu/g dry root tissue). Because pre-adapted begonias accumulated a large amount of Cu, mainly in their roots, they could be used for phytostabilization of Cu-contaminated soils. In addition, as a flowering plant, begonias can be used to create aesthetically pleasing remediation sites.

• Journal of the Korean Chemical Society
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• 제32권3호
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• pp.227-232
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• 1988

A kinetic study was made to determine the mechanism of the aquation of $cis-[Co(en)_2(NH_3)Cl]^{2+}\;in\;Hg^{2+}$ aqueous solution. The progress of reaction was followed UV/vis-spectrophotometrically by a measurement of the absorbance at a specific wave length (530nm) of $cis-[Co(en)_2(NH_3)Cl]^{2+}$ as a function of time. The experimental results have shown that the reaction rate is dependent upon the concentration of $Hg^{2+}$ that act as a catalyst. And it was found that the overall reaction proceed with second order, first order with respect to Co(III) complex and $Hg^{2+}$. Activation parameters, ${\Delta}H^{\neq}\;and\;{\Delta}S^{\neq}$, were obtained as 12.9 kcal/mol and -19.3 e.u., respectively. We have proposed a plausible reaction mechanism which is consistent with the observed rate equation.