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ABSTRACT: By the flow modulation growth, we suggest the existence of an intermediate layer at the surface of InP and InGaP during the growth. Its transient behavior was analyzed in connection to the surface segregation phenomena.
Indium Phosphide and Related Materials, 2005. International Conference on; 06/2005
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ABSTRACT: Obtusifoliol 14alpha-demethylase is a plant orthologue of sterol 14alpha-demethylase (CYP51) essential in sterol biosynthesis. We have prepared CYP51 antisense Arabidopsis in order to shed light on the sterol and steroid hormone biosynthesis in plants. Arabidopsis putative CYP51 cDNA (AtCYP51) was obtained from Arabidopsis expressed sequence tag (EST) library and its function was examined in a yeast lanosterol 14alpha-demethylase (Erg11) deficient mutant. A recombinant AtCYP51 protein fused with a yeast Erg11 signal-anchor peptide was able to complement the erg11 mutation, which confirmed AtCYP51 to be a functional sterol 14alpha-demethylase. AtCYP51 was then used to generate transgenic Arabidopsis by transforming with pBI vector harboring AtCYP51 in the antisense direction under CaMV35S promoter. The resulting transgenic plants were decreased in accumulation of AtCYP51 mRNA and increased in the amount of endogenous obtusifoliol. They showed a semidwarf phenotype in the early growth stage and a longer life span than control plants. This newly found phenotype is different from previously characterized brassinosteroid (BR)-deficient campesterol biosynthesis mutants.
Biochemical and Biophysical Research Communications 08/2001; 285(1):98-104. · 2.48 Impact Factor
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ABSTRACT: The transposon Tn5 carries a gene, ble, which confers resistance to bleomycin (Bm) and gives a survival advantage to its host cell. We found that the ble gene product, designated BLMT, is a binding protein with a strong affinity for Bm. BLMT quenched both the antibacterial and DNA-cleaving activities of Bm, when incubated with the antibiotic. An electron spin resonance spin-trapping analysis showed that BLMT inhibits the generation of Bm-induced hydroxyl radical, by trapping Bm but not the hydroxyl radical. Western blot analysis using an anti-BLMT monoclonal antibody revealed that BLMT is immunologically distinct from Bm-binding proteins from Streptomyces verticillus, Staphylococcus aureus and Streptoalloteichus hindustanus. Escherichia coli, transformed with a mutant ble having leucine instead of proline at N-terminal amino acid position 7, lost resistance to Bm, although the cell maintained the survival benefit. This suggests that the Bm resistance mediated by ble is independent of its ability to give a survival advantage to the host bacterium.
FEBS Letters 02/1999; 442(1):34-8. · 3.54 Impact Factor
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ABSTRACT: In selective-area MOVPE of InP, we often encounter an abnormally grown ridge near the mask edge accompanied by various facets. The effect of mask shape and growth conditions on the shape and cross-sectional area of the ridge was investigated. The cross-sectional area showed a parabolic increase with time. The direction of the stripe growth area had a significant effect on the edge growth. When the stripe was oriented to [1 0 0] or [0 1 0] direction, the cross-sectional area of the ridge showed a significant increase and was accompanied by a (1 1 0) facet, although the edge growth in other conditions was often accompanied by (1 1 1)B facets. A numerical simulation, incorporating the surface diffusion of a precursor, was introduced and the amount of the edge growth was reproduced. The effect of growth conditions on the cross-sectional area of the edge growth was interpreted in terms of the surface diffusion length of the precursor on both masks and growth areas.
Journal of Crystal Growth 287(2):668-672. · 1.73 Impact Factor
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ABSTRACT: At InGaP-on-GaAs heterointerface, transition layer is formed during metalorganic vapor phase epitaxy (MOVPE) growth that can affect device properties. Many studies of this transition layer have been done but the characterization methods used are not direct measures of the atomic structure at the heterointerface. In this study, we investigated the abruptness and thickness of the InGaP-on-GaAs transition layers by field-emission Auger electron spectroscopy, by which a depth profile with a resolution of abruptness of 30 Å or below can be obtained. The group V switching position relative to that of In goes deeper into the GaAs with increasing PH3 supply, suggesting an initial, quick replacement of As atoms with P atoms followed by a slow P diffusion into the bulk GaAs. Changes of abruptness of the As or P profiles at the heterointerface with varying PH3 supply on the GaAs surface are not observed. Furthermore, we evaluated the effect of the GaAsP-like transition layers on the turn-on voltage of an InGaP emitter HBT. A linear relationship is shown between the shift of the group V switching position and the HBT turn-on voltage, which is consistent with the assumption that current flow decreases at the transition layer. Calculated difference of conduction band energy between InGaP and the transition layer is 0.15 eV for the sample with ordered InGaP and 0.04 eV for disordered InGaP, is consistent with the difference of the band gap energies between ordered and disordered InGaP. Calculated P compositions are 0.52 and 0.35, respectively.
Journal of Crystal Growth 298:85-89. · 1.73 Impact Factor
