• Title/Summary/Keyword: Se(-II)

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Complexation of Cadmium(II) with Soil Fulvic Acid

  • Me Hae Lee;Se Young Choi;Hichung Moon
    • Bulletin of the Korean Chemical Society
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    • v.14 no.4
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    • pp.453-457
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    • 1993
  • Cadmium(II) complexation by a well characterized soil fulvic acid (FA) from the Okchun Metamorphic Belt were studied at pH of 6.0 in 0.1 M $NaClO_4$ using the ultrafiltration technique. The conditional stability constants thus obtained were log K= 3.90${\pm}$0.15 and 3.99${\pm}$0.12 $L{\cdot}mol^{-1}$ at fulvic acid concentrations of 101 and 226 mg${\cdot}L^{-1}$ respectively. When free cadmium ion concentration was measured directly using an ion selective electrode, log K of 4.12${\pm}$0.03 $L{\cdot}mol^{-1}$ was obtained. These results show that fulvic acid forms predominately 1 : 1 complex with $Cd^{2+}$ ions. The maximum binding ability of this polyelectrolyte material was 0.886 mmol Cd/g FA. The average gram formula weight of fulvic acid was estimated to be 1130 daltons.

X-ray Structure and Electrochemical Properties of Ferrocene-Substituted Metalloporphyrins

  • Kim, Jin Won;Lee, Seok U;Na, Yong Hwan;Lee, Gi Pyeong;Do, Yeong Gyu;Jeong, Se Chae
    • Bulletin of the Korean Chemical Society
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    • v.22 no.12
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    • pp.1316-1322
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    • 2001
  • Transition metal complexes of novel mono- and di-ferrocene-substituted porphyrins have been synthesized and characterized by structural and electrochemical methods. The X-ray structures of Mn(FPTTP)Cl and Mn(DFTTP)Cl showed the distorted square pyramidal coordination geometry with syn configuration of chloride and ferrocenyl substituents. The electrochemistry of ferrocene-substituted porphyrins and their metal complexes has been determined to elucidate the ${\pi}-conjugation$ effect of the porphyrin ring. The ferrocenyl group of H2FPTTP underwent a reversible one-electron transfer process at 0.30 V, indicating the good electron donating effect of the phorphyrin ring to the ferrocene substituent. The redox potential of the ferrocenyl subunit and porphyrin ring was affected by the central metal ions of the metalloporphyrins, that is, Zn(II) and Ni(II) made the oxidation of ferrocene much easier and Mn(III) made it harder. The ferrocene subunits of H2DFTTP interacted electrochemically with each other with peak splitting of 0.21 V. The strength of the electrochemical interactions between the two ferrocenyl substituents can be controlled by central metal ions of metalloporphyrins.

Influence of Daily Water Temperature Changes on Chemiluminescent Response of Phagocytes and Mortality in Cultured Gray Mullet (Mugil cephalus L.)

  • Kim Ki Hong;Hwang Yoon Jung;Kwon Se Ryun;Huh Sung-Hoi
    • Fisheries and Aquatic Sciences
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    • v.3 no.2
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    • pp.78-82
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    • 2000
  • The influence of daily water temperature changes on chemiluminescent (CL) response of phagocytes, plasma glucose level and mortality in cultured gray mullet (Mugil cephalus) was investigated. Among three experimental temperature groups, the fish in group I and group II were maintained constantly at $27^{\circ}C$ and $29^{\circ}C$, respectively, and those in group III were suffered daily elevation of water temperature from $27^{\circ}C$ to $29^{\circ}C$ for 5 hours, then restored again to $27^{\circ}C$. After 1 week of maintaining at each experimental tank, the fish in group III showed significantly lower CL peak value (p < 0.01) and higher plasma glucose levels (p < 0.05) than those in group I and group II. The cumulative mortality of group III was $86.9\%$ within 3 days after being subjected to acute handling stress. On the other hand, the cumulative mortalities of group I and group II were $12.5\%$ and $19.2\%$, respectively. In conclusion, gray mullet farms, especially, in the vicinity of thermoelectric power plants should avoid stressing the fish during periods of high water temperature.

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Design of Swing Arm Type's for Small Sized ODD (초소형 광디스크 드라이브를 위한 스윙암 타입 엑추에이터 설계)

  • Oh, Je-Seung;Park, Se-June;Lee, Dong-Ju;Jung, Ho-Seop;Park, No-Cheol;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.70-74
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    • 2004
  • There are many researches being in process to develop the information storage devices applying to the portable devices recently. Based on this need, the information storage devices have to be satisfied with the fast access time, the robustness of the system, high data transfer rate and lower media price. The total size of the drive must design to adapt the portable devices such as CF II card or PC II card size. This paper proposes the swing arm type actuator to insert the designed actuator in the drive of the CF II size. Hereafter the research will be going on to be suitable to the physical standard and design the focus magnetic circuit newly. The swing arm type actuator including this circuit is designed to have the dynamic characteristic satisfying the mechanical specification as well as the BD 1x. Finally, the adaptability to the portable devices was demonstrated by the finite element analysis and optimization of structural part.

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Complexation of Cadmium(Ⅱ) with Humic Acids: Effects of pH and Humic Acid Origin

  • Lee, Mee-Hae;Choi, Se-Young;Chung, Kun-Ho;Moon, Hi-Chung
    • Bulletin of the Korean Chemical Society
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    • v.14 no.6
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    • pp.726-732
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    • 1993
  • A comparative study on cadmium(II) complexation with three well characterized humic acids (SHA: soil humic acid from the Okchun Metamorphic Belt; AqHA: aquatic humic acid from Gorleben underground aquifer, Germany; CoHA: commercially available humic acid from the Aldrich Co.) was carried out in 0.1 M $NaClO_4$ at different solution pH(5.0, 5.5, and 6.0) using the ultrafiltration technique. The maximum binding ability (MBA) of the humic acids for cadmium(II) was observed to vary with their origins and solution pH. The results suggest that 1 : 1 complex predominates within the experimental range, and the conditional stability constants were calculated based on the assumption of cooperative binding, yielding log K values that were quite similar (CoHA: 4.17${\pm}$0.08; AqHA: 4.14${\pm}$0.07; SHA: $4.06{\pm} 0.12\;l\;mol^{-1}$ at pH 6.0) irrespective of humic acid origins or pH. By contrast a nonlinear Schatchard plot was obtained, using the cadmium(II) ion selective electrode speciation analysis method, which indicated that humic acid may have two or more classes of binding sites, with $log\;K_1\;and\;log\;K_2$ of 4.73${\pm}$ 0.08 and $3.31{\pm}0.14\;l\;mol^{-1}$ respectively.

다당류를 이용한 중금속 이온의 흡착특성 비교

  • Kim, Se-Gyeong;Yun, Hyeon-Sik
    • 한국생물공학회:학술대회논문집
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    • 2000.04a
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    • pp.386-389
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    • 2000
  • Polysaccharides are very effective adsorbents for heavy metals. In this study, the adsorption characteristics of various polysaccharides for heavy metal adsorption were investigated. Tested polysaccharides were homogeneous polysaccharides such as curdlan, chitin, starch, cellulose, Avicel, and Solka floc and heterogeneous polysaccharides such as zooglan, locust bean gum, ghatti gum, pectin, and xylan. Lead(II) adsoption characteristic on these polysaccharides followed Freundlich isotherm and the isotherm parameters were calculated. For adsorption of lead(ll), Avicel, starch, and zooglan were found to be good adsorbents.

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