Bibliografía

Reaction of the anion-deficient, cation-ordered perovskite phase Ba₂YFeO₅ with 80 atm of oxygen pressure at 410 °C results in the formation of the Fe⁴⁺ phase Ba₂YFeO_5.5. The topochemical insertion of oxide ions lifts the inversion symmetry of the centrosymmetric host phase, Ba₂YFeO₅ (space group <i>P</i>2₁/<i>n</i>), to yield a noncentrosymmetric (NCS) phase Ba₂YFeO_5.5 (space group <i>Pb</i>2₁<i>m</i> (No. 26), <i>a</i> = 12.1320(2) Å, <i>b</i> = 6.0606(1) Å, <i>c</i> = 8.0956(1) Å, <i>V</i> = 595.257(2) ų) confirmed by the observation of second-harmonic generation. Dielectric and PUND ferroelectric measurements, however, show no evidence for a switchable ferroelectric polarization, limiting the material to pyroelectric behavior. Magnetization and low-temperature neutron diffraction data indicate that Ba₂YFeO_5.5 undergoes a magnetic transition at 20 K to adopt a state which exhibits a combination of ferromagnetic and antiferromagnetic order. The symmetry breaking from centrosymmetric to polar noncentrosymmetric, which occurs during the topochemical oxidation process is discussed on the basis of induced lattice strain and an electronic instability and represents a new strategy for the preparation of NCS materials that readily incorporate paramagnetic transition metal centers

The phylogenetic tree based on 16S rDNA of strain Q3 and those of herbicide-degrading species.

<p>Q3 and other two quinclorac degrading bacteria, such as <i>Burkholderia cepacia</i> and <i>Bordetella petrii</i> are in different branches of the tree.</p

Effect of initial quinclorac concentration on Q3 growth and degradation of quinclorac.

<p>Both growth and quinclorac degradation of Q3 reached peak values when initial quinclorac concentration was 20 mg/L.</p

Bioremediation of strain Q3 on leaf length, leaf width and plant height of tobacco.

<p>Note: Values are the means and standard deviation (sd) of three replicates. Values are percentage of leaf length, leaf width and plant height of treatments compared with controls without quinclorac phytotoxicity.</p><p>Bioremediation of strain Q3 on leaf length, leaf width and plant height of tobacco.</p

Morphological characteristics of strain Q3.

<p>Colony morphology on LB plate (left) and cell morphology under electron microscope (right).</p

Mass spectrum of quinclorac degradation products of Q3.

<p>The molecular formula of quinclorac and three degradation products are labeled.</p