• Journal of Life Science
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• v.20 no.1
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• pp.17-21
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• 2010

Phytoextraction is a method of phytoremediation using plants to clean up metal-contaminated soils. Recently, various chelating agents were used in this method to increase the bioavailability of metals in soils. Even though phytoextraction is an economic and environmentally friendly method, this cannot be applied in highly metal-contaminated areas because plants will not normally grow in such conditions. This research focuses on identifying chelating agents which are biodegradable and applicable to highly metal-contaminated areas. Copper (Cu) as a target metal and cysteine (Cys), histidine (His), citrate, malate, oxalate, succinate, and ethylenediamine (EDA) as biodegradable chelating agents were selected. Ethylenediamine tetracyclic acid (EDTA) was used as a comparative standard. Plants were grown on agar media containing various chelating agents with Cu to analyze the effect on root growth. Cys, His, and citrate strongly diminished the inhibitory effect of Cu on root growth of plants. The effect of oxalate was weak, and malate and succinate did not show significant effects. EDTA diminished and EDA promoted the inhibitory effects of Cu on root growth. These effects of chelating agents are correlated with Cu uptake into the roots. In conclusion, as biodegradable chelating agents, Cys, His, and citrate are good candidates for highly Cu-contaminated areas, while EDA can be useful in phytoextraction for Cu.

• Korean Journal of Crystallography
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• v.7 no.1
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• pp.8-19
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• 1996

Cholestryl Methyl and Propyl Carbonate(CH3OCOOC27H45, C3H7OCOOC27H45) are monoclinic, space group P21, with a=17.014(1), b=7.682(1), c=10.612(1)Å, β=103.05(1)°, Z=2, V=1351.16Å3, Dc=1.09 g/cm3 for methyl carbonate, and with a=13.683(1), b=11.864(2), c=18.904(2)Å, β=106.30(1)°, Z=4, V=2945.4Å3, Dc=1.06 g/cm3, Dm=1.06 g/cm3 for propyl carbonate. The intensity data were collected on an Enraf-Nonius CAD-4 diffractometer with a graphite monochromated Cu-Kα radiation. The structure was solved by direct methods and refined by full matrix least-squares methods. The final R factor was 0.051 for 2323 observed reflections for methyl carbonate and 0.074 for 3323 observed reflections for propyl carbonate. Compared with other cholesteryl derivatives, the cholesteryl ring and tail region of the molecules are normal. The molecules are stacked in clearly separated layers. At center of the layer, there are cholesteryl-C(17) side chain interactions. The interface region between layers is occupied by the loosely packed methyl carbonate chains. The structure of cholesteryl propyl carbonates have two propyl carbonates have two molecules(A, B) that are not related by crystal symmetry and have their tetracyclic system almost parallel to each other. Cholesteryl-cholesteryl interactions between symmetry related A-molecules, and cholesteryl-C(17) side chain interactions between symmetry related B-molecules occur at the center of the layers and these molecules stack along 2₁ screw axes. There are also C(17)chain-carbonate chain and C(17)chain-C(17)chain interactions in the interface region between layers. There is efficient packing between cholesteryl ring systems in propyl carbonates. Temperature ranges of cholesteric mesophases of cholesteryl alkyl cargonates are narrow for methyl, pentyl and hexyl carbonates, and rather broader for ethyl and propyl carbonates. Cholesteryl-isotropic transitions change very little with chain length.