• Journal of Environmental Science International
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• v.21 no.4
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• pp.421-435
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• 2012

Novel $N_2O_2$ tetradentate ligands, H-3BPD and H-2BPD were synthesized. Hydrochloric acid salts of Br-3BPD, Cl-3BPD, Br-2BPD and Cl-2BPD having Br and Cl substituents at the $para$ position of the phenol hydroxyl group, were synthesized. The ligands were characterized by C. H. N atomic analysis, $^1H$ NMR, $^{13}C$ NMR, UV-visible, and mass spectra. The proton dissociation constants ($logK_n{^H}$) of the phenol hydroxyl group and secondary amine of the synthesized $N_2O_2$ ligands were shown by four step wise values. The orders of the calculated overall proton dissociation constants ($log{\beta}_p$) were Br-3BPD < Cl-3BPD < H-3BPD in case of 3BPD and Br-2BPD < Cl-2BPD < H-2BPD in case of 2BPD respectively. The order agreed well with that of $para$ Hammett substituent constants(${\delta}_p$). The stability constants($logK_{ML}$) of the complexes between the synthesized ligands and transition metal(II) ions agreed with the order of $log{\beta}_p$ of the ligands. The order of the $logK_{ML}$ value of the each transition metal (II) ion was Co(II) < Ni(II) < Cu(II) > Zn(II) > Cd(II) > Pb(II), which agreed well with that of Iriving-Williams series.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.1
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• pp.11-23
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• 1998

The purpose of this study was to survey chemical distribution of inorganic elements and ions in the submicron particles, to characterize qualitatively emitting sources by factor analysis, and finally to reveal existing patterns in terms of chemical compounds by a stepwise multiple regression analysis. Total of 141 samples were collected by a cascade impactor from 1989 to1996. Fifteen chemical species (Al, Ba, Cd, K, Pb, Cu, Fe, Ni, $Cl^-, NO_3^-, SO_4^{2-}, K^+, Mg^{2+}, Ca^{2+}, and Na^+$) were characterized by AAS and IC. The study showed that average seasonal levels of submicron particulate matters $(d_p<0.43 \mum)$ were 18.7 $\mug/m^3$ in spring, 15.5 $\mug/m^3$ in summer, 15.7 $\mug/m^3$ in fall, and 24.5 $\mug/m^3$ in winter, respectively. All of the anion concentrations in the particle were highest in the winter season. By applying a factor analysis, 5 source patterns were qualitatively obtained, such as sulfate related source, nitrate related source, oil burning source, calcium related source, and coal combustion source. Finally, when applying a stepwise multiple regression analysis, the results clearly showed that $Na^+ and Ca^{2+}, K^+ and Ca^{2+}, NO_3^-$ and relative humidity, $Cl^-$ and ambient temperature, $Ca^{2+} and Cl^-, Mg^{2+} and SO_4^{2-}, Na^+ and NO_3^-, and Ca^{2+} and NO_3^-$, respectively, are negatively contributed to each other. As a result of those statistical analysis, we could suggest that some chemical compounds in the submicron particles such as$NaNO_3, MgSO_4, Ca(NO_3)_2, and CaCl_2$ may not exist on the filter as final composing products; however, other compounds may possibly exist in the form of $Mg(NO_3)_2, CaSO_4, Na_2SO_4, K_2SO_4, MgCl_2, NaCl, and KCl$. Thus, it must be necessary to identify differences between the results of above statistical analysis and of the real world by laboratory experiments.

• The Korean Journal of Ecology
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• v.23 no.1
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• pp.9-15
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• 2000

The effects of clearcutting on soil chemical ingredients and stream water quality have been investigated at a natural deciduous forest catchment within the Seoul National University Research Forest in Mt. Paekun, Chunnam province during the periods of 1993 to 1998. Soil chemical ingredients and stream water qualities were monitored at a 13 ha clearcutting site and a non-treatment site nearby. During the first and second years after harvesting, the levels of total-N, and exchangeable ions (K/sup ＋/, Na/sup ＋/, Ca/sup 2＋/, Mg/sup 2＋/) decreased compared to the values of before harvesting. During the fifth years after harvesting, these levels were significantly higher than those during the first and second years after harvesting. But the chemical characteristics of soil were not changed at all. pH of water in the harvesting area was 6.5 in stream water. Among the nutrients, Cd, Pb, Cu, and phosphate were not found, and the level of BOD reached at the level of the domestic use suitable for drinking. Turbidity, odor, taste, NH/sub 4//sup ＋/ -N, NO/sub 3//sup -/-N, standard plate count, and coliform were also low enough to be used as the domestic use for drinking by the near villagers. During the first and second years after harvesting, BOD increased to about 1 ppm. For that reason, the harvesting planning should be built in the harvesting area in consideration of the control of water quality in the stream.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3777-3787
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• 2012

Three kinds of 3D isomorphous and isostructural coordination polymers, namely, $\{[Ln_2(PDA)_3(H_2O)_3]{\cdot}0.25H_2O\}_{\infty}$ (Ln = La(1), Sm(2), and Gd(3)) ($PDA^{2-}$ = pyridine-2,6-dicarboxylate anion) have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermal analyses and single crystal X-ray diffraction. In these MOFs, Ln(III) centers adopt eight-coordinated and nine-coordinated with the $N_1O_7$ and $N_2O_7$ donor sets to construct distorted trianglar dodecahedron geometry and tricapped trigonal prism configurations, respectively. Based on the building block of tetranuclear homometallic $Ln_4C_4O_8$ unit (16-membered ring), 1-3 are connected into highly ordered 2D sheets via O-C-O linkers and further constructed into 3D architectures through hydrogen bonds. Crystallographic parameters suggest that the lanthanide contraction effect exist in these coordination polymers. Luminescent properties of the lanthanide-based MOFs (metal-organic frameworks) have been measured at room temperature, which reveal that they presenting ionselective characters toward certain metals, such as $Mg^{2+}$, $Cd^{2+}$ and $Pb^{2+}$ ions.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1581-1586
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• 2006

A La (III) ion-selective membrane sensor has been fabricated from poly vinyl chloride (PVC) matrix membrane, containing 3-hydroxy-N'-(pyridin-2-ylmethylene)-2-naphthohydrazide (HPMN) as a neutral carrier, potassium tetrakis (p-chlorophenyl) borate (KTpClPB) as an anionic excluder and ortho-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The effects of membrane composition and pH as well as the influence of the anionic additive on the response properties were investigated. The sensor with 30% PVC, 62% solvent mediator, 6% ionophore and 2% anionic additive, shows the best potentiometric response characteristics. It displays a Nernstian behavior (19.2 mV per decade) across the range of $1.0{\times}10^{-2}-1.0{\times}10^{-7}$ M. The detection limit of the electrode is $7.0{\times}10^{-8}$ M ($\sim$10 ng/mL) and the response time is 15 s from $1.0{\times}10^{-2}$ up to $1.0{\times}10^{-4} $M and 30 s in the range of $1.0 {\times}10^{-5}-1.0{\times}10^{-7}$ M. The sensor can be used in the pH values of 3.0-9.0 for about seven weeks. The membrane sensor was used as an indicator electrode in the potentiometric titration of lanthanum ions with EDTA. It was successfully applied to the lanthanum determination in some mouth wash preparations.

• Applied Biological Chemistry
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• v.35 no.2
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• pp.82-86
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• 1992

This research was carried out to investigate antimutagent effect of peach enzymatic browning reaction products(PEBRP) obtained by reacting each of polyphenol compounds with oxidase extracted from Korea-cultivated peach. In methods, rec-assay with B. subtilis strains $H17(rec^+)\;and\;M45(rec^-)$, and Ames test with S. typhimurium TA98 and TA100 were used. The spore rec-assay of PEBRP, pyrogallol, hydroxyhydroquinone, homocatechol and caffeic acid were not showed mutagenicity. In the effects of various metal ions$(Al^{3+},\;Cu^{2+},\;Fe^{2+},\;Mn^{2+},\;Ni^{2+},\;Pb^{2+},\;Zn^{2+})$ on the rec-assay, all PEBRP except caffeic acid was increased inhibition zone(5 mm) only with $Zn^{2+}$. In paticular, the Py-PEBRP was decreased the difference of inhibition zone of growth on MMC(mitomycin C). In results of Ames test, all PEBRP were not showed mutagenicity on S. typhimurium TA98 and TA100; however, Ca-PEBRP and Hca-PEBRP were suppressed mutagenic effects on Trp-P-1 and B(a)P in the presence of S-9Mix.

• Journal of Microbiology and Biotechnology
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• v.21 no.3
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• pp.256-262
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• 2011

A 20.9-kDa metalloprotease was isolated from dried fruiting bodies of the wild basidiomycete mushroom Lepista nuda. The N-terminal amino acid sequence of the protease was seen to be ATFVLTAATNTLFTA, thus displaying no similarity with the sequences of previously reported metalloproteases. The protease was purified using a procedure that entailed ion-exchange chromatography on CM-Cellulose, Q-Sepharose, and Mono S, and FPLC-gel filtration on Superdex 75. The protease functioned at an optimum pH of 7.0 and an optimum temperature of $50^{\circ}C$. It was also noted that the protease demonstrated a proteolytic activity of 1,756 U/mg toward casein. The $K_m$ of the purified protease toward casein was 6.36 mg/ml at a pH of 7.0 and with a temperature of $37^{\circ}C$, whereas the $V_{max}$ was 9.11 ${\mu}g\;ml^{-1}\;min^{-1}$. The activity of the protease was adversely affected by EDTA-2Na, suggesting that it is a metalloprotease. PMSF, EGTA, aprotinin, and leupeptin exerted no striking inhibitory effect. The activity of the protease was enhanced by $Fe^{2+}$, but was curtailed by $Cd^{2+}$, $Cu^{2+}$, $Hg^{2+}$, $Pb^{2+}$, $Zn^{2+}$, and $Fe^{2+}$ ions. The protease also exhibited inhibitory activity against HIV-1 reverse transcriptase with an $IC_{50}$ value of 4.00 ${\mu}M$. The $IC_{50}$ values toward hepatoma Hep G2 and leukemia L1210 cells in vitro were 4.99 ${\mu}M$ and 3.67 ${\mu}M$, respectively.

• Journal of Microbiology and Biotechnology
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• v.22 no.5
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• pp.690-698
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• 2012

Cr-B2, a Gram-negative hexavalent chromium [Cr(VI)] reducing bacteria, was isolated from the aerator water of an activated sludge process in the wastewater treatment facility of a dye and pigment based chemical industry. Cr-B2 exhibited a resistance for 1,100 mg/l Cr(VI) and, similarly, resistance against other heavy metal ions such as $Ni^{2+}$ (800 mg/l), $Cu^{2+}$ (600 mg/l), $Pb^{2+}$ (1,100 mg/l), $Cd^{2+}$ (350 mg/l), $ZN^{2+}$ (700 mg/l), and $Fe^{3+}$ (1,000 mg/l), and against selected antibiotics. Cr-B2 was observed to efficiently reduce 200 mg/l Cr(VI) completely in both nutrient and LB media, and could convert Cr(VI) to Cr(III) aerobically. Cr(VI) reduction kinetics followed allosteric enzyme kinetics. The $K_m$ values were found to be 43.11 mg/l for nutrient media and 38.05 mg/l for LB media. $V_{max}$ values of 13.17 mg/l/h and 12.53 mg/l/h were obtained for nutrient media and LB media, respectively, and the cooperativity coefficients (n) were found to be 8.47 and 3.49, respectively, indicating positive cooperativity in both cases. SEM analysis showed the formation of wrinkles and depressions in the cells when exposed to 800 mg/l Cr(VI) concentration. The organism was seen to exhibit pleomorphic behavior. Cr-B2 was identified on the basis of morphological, biochemical, and partial 16S rRNA gene sequencing chracterizations and found to be Acinetobacter sp.

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1529-1532
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• 2005

A simple and cost effective method for separation and preconcentration of Ag(I) at the $10^{-7}\;mol\;L^{-1}$ level in the environmental and mineral samples is present. The method is based on the flotation of Ag(I)-iodide complex as an ion-associate with ferroin in pH of 4 from a large volume of an aqueous solution (500 mL) using nheptane. The floated layer was then dissolved in dimethylsulfoxide (DMSO) for the subsequent spectrophotometric determination. Beer's law was obeyed over a range of 2.0 ${\times}$ $10^{-7}$-4.0 ${\times}$ $10^{-6}$ mol $L^{-1}$ with the apparent molar absorptivity of 2.67 ${\times}$ $10^5$ L $mol^{-1}\;cm^{-1}$. The detection limit (n = 5) was 4 ${\times}$ $10^{-8}$ mol $L^{-1}$, and RSD (n = 5) obtained for 2.0 ${\times}$ $10^{-6}$ mol $L^{-1}$ of Ag(I) was 2.2%. The interference effects of a number of elements was studied and found that only $Hg^{2+}$ at low concentration, and $Pb^{2+}$, $Cd^{2+}$, $Cu^{2+}$, and $Fe^{3+}$ ions at moderately high concentrations were interfered. To overcome on these interference effects, the solution was treated with EDTA at a buffering pH of 4 and passed through a column containing Amberlite IR-120 ionexchanger resin, just before the flotation process. The proposed method was applied to determine of Ag(I) in a synthetic waste water, a photographic washing sample and a geological sample and the results was compared with those obtained from the flame atomic absorption spectrometry. The results were satisfactorily comparable with together, so that the applicability of the proposed method was confirmed in encountering with the real samples.

• Journal of Microbiology and Biotechnology
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• v.9 no.2
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• pp.173-178
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• 1999

The extracellular cytosine deaminase (EC 3.5.4.1) from Chromobacterium violaceum YK 391 was purified 264.7-fold with an overall yield of 14.3%. The enzyme was for the first time homogeneous by the criteria of polyacrylamide gel electrophoresis performed in the absence and in the presence of sodium dodecyl sulfate. The molecular weight of the purified enzyme was estimated to be about 156 kDa. The enzyme consisted of two identical subunits of approximate molecular weight 78 kDa. The isoelectric point of the enzyme was pH 5.55. The enzyme had a pH optimum of 7.5 and a temperature optimum of around 40 to $45^{\circ}C$. Besides cytosine, the enzyme deaminated 5-fluorocytosine, cytidine, 5-methylcytosine, and 6-azacytosine, but not 5-azacytosine. The extracellular cytosine deaminase is believed to be unique because it was active not only on cytosine but also on cytidine. The apparent $K_m$ values for cytosine, 5-fluorocytosine, cytidine, and 5-methylcytosine were determined to be 1.55 mM, 5.52 mM, 10.4 mM, and 67.2 mM, respectively. The enzyme activity was strongly inhibited by heavy metal ions such as $Fe^{2+},Pb^{2+},Cd^{2+},Zn^{2+}, Hg^{2+}, and Cu^{2+}$ at 1 mM, and completely by $\alpha,\alpha$'-dipyridyl, and $\rho$-chloromercuribenzoate at 1 mM, and weakly inhibited by 1mM ο-phenanthroline. The enzyme activity was not affected by various nucleosides and nucleotides.