Seon-A Kim

Characterization of Pseudomonas sp. BCNU 171 tolerant to organic solvents.

An organic solvent‐tolerant bacterium, designated as Pseudomonas sp. BCNU 171, was isolated from industrial wastewater in Korea, on the basis of its ability to survive in the presence of benzene, toluene, propylbenzene and xylenes. Its tolerance limits were 8 mM in phenol, 20 mM in benzene and 60 M in toluene. The log P value of phenol was approximately 1.5, which indicates that Pseudomonas sp. BCNU 171 exhibits the highest tolerance to organic solvents. Pseudomonas sp. BCNU 171, a relative of P. putida, P. mosselii and P. moteillii based on phylogenetic analyses using 16S rRNA sequences, was designated as a new sp. that is tolerant to a wide spectrum of organic solvents, especially xylene isomers. These findings may facilitate the understanding of organic solvent tolerance in bacterial cells. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of A-site Excess on the Piezoelectric Properties of (K0.48 Na0.52)1+x(Nb0.55Ta0.45)O3 Thin Films

Lead-free polycrystalline (K0.48Na0.52)1+x(Nb0.55Ta0.45)O3 (x = 0, 0.01, 0.02 and 0.03) thin films have been grown on Pt(111)/Ti/SiO2/Si substrates using KrF excimer laser ablation to investigate the effects of A-site ion excess. The film at x = 0.01 exhibited good ferroelectric hysteresis loop with a remnant polarization 2Pr of 30 μC/cm2 and coercive field 2Ec of 61 kV/cm. The piezoelectric coefficient d33,f of the KNNT film with x = 0.01 was found to amount to 79 pm/V. These improved ferroelectric and piezoelectric properties were attributed to the excess of A-site Na and K ions.

Leakage Current Behaviors of SrTiO3 Capped Mn-doped Polycrystalline BiFeO3 Thin Film

The polycrystalline Mn 1% doped BFO (BFMO) thin film was deposited on Pt(111)/Ti/SiO2/Si(100) substrate by pulsed laser deposition. A thin SrTiO3 capping layer was grown on top of deposited Bi(Fe0.99Mn0.01)O3 thin film. The structural and electrical properties of STO/BFMO thin film were investigated. By capping a thin STO on top of BFMO, leakage current density of capacitor was improved greatly compare to that of the pure BFMO without degrading ferroelectricity.

Study on Pandoraea sp. BCNU 315 Isolated from Soil

Bacteria that antagonize plant pathogenic fungi were isolated from the sediment soil at the Ansan industrial estate. One isolate of them showed growth inhibition of Rhizoctonia solani, Botrytis cenerea, and Fusarium oxysporum. This strain was identified as Pandoraea sp. based on phenotypic and phylogenetic characteristics and termed Pandoraea sp. BCNU 315. Tryptone as nitrogen source and sucrose as carbon source were found to be most effective for the microbial growth. In addition, the optimum temperature and pH for microbial growth were and pH 7.0, respectively. The substances generated from Pandoraea sp. BCNU 315 were purified and analyzed by column chromatography, HPLC, GC-MS and NMR. As a result, one compound was determined to be indole, another compound was predicted as cyclopentadecaheptene. Detailed structural clarification of the all of the rest six compounds from Pandoraea sp. BCNU 315 has to be accompanied in the further studies.