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

Discrete Element Simulation of Gas–Solid and Gas–Liquid–Solid Flows

Multiphase flow (i.e., gas–solid flow and gas–liquid–solid flow) extensively exists in industries, yet the strong coupling between different phases poses challenges in the discrete element method (DEM)-based model establishment. This work developed a fully coupled framework by combining computational fluid dynamics (CFD) with DEM, with the further extension to incorporate volume-of-fluid (VOF) to study multiphase flow systems. A smoothing method is implemented to allow the grid size to be close to or smaller than the diameter of the particles, benefiting the subsequent interphase and interfacial interactions calculation. Iso-Advector, an advanced VOF-based surface-capturing method, is further introduced to describe interface evolution and interfacial interactions effectively. The integrated model is verified in three benchmark cases, i.e., a quasi-two-dimensional spouted bed, a fully three-dimensional spout-fluid bed, and a dam-break flow. The numerical results agree well with experimental measurements, confirming the model’s reliability in simulating multiphase flow systems

Synthesis and Selective Topochemical Fluorination of the Cation and Anion-Vacancy Ordered phases Ba₂YCoO₅ and Ba₃YCo₂O_7.5

The synthesis and characterization of two cation-ordered, anion-vacancy ordered phases, Ba₂YCoO₅ and Ba₃YCo₂O_7.5, is described. Neutron powder diffraction data reveal both phases adopt structures in which octahedral Y³⁺ and tetrahedral Co³⁺ centers are ordered within a “cubic” perovskite lattice. The unusual ordered pattern adopted by the cations can be attributed to the large concentration of anion vacancies within each phase. Reaction of Ba₂YCoO₅ with CuF₂ under flowing oxygen topochemically inserts fluorine into the host material to form Ba₂YCoO₅F_0.42(1). In contrast Ba₂YCoO₅ does not intercalate oxygen, even under high oxygen pressure. The selective insertion of fluorine, but not oxygen, into Ba₂YCoO₅ is discussed and rationalized on the basis of the lattice strain of the resulting oxidized materials. Magnetization and neutron diffraction data reveal Ba₃YCo₂O_7.5 and Ba₂YCoO₅F_0.42 adopt antiferromagnetically ordered states at low-temperature, while in contrast Ba₂YCoO₅ shows no sign of long-range magnetic order

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 pH on degradation of quinclorac and growth of Q3.

<p>Both growth and quinclorac degradation of Q3 reached peak values at pH of 8.</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

Possible F4 quinclorac degradation products and pathways.

<p>Possible F4 quinclorac degradation products and pathways.</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

Growth curve and degradation curve of F4 and <i>E coli</i> Top10 (control) after different culture timed durations.

<p>Growth curve and degradation curve of F4 and <i>E coli</i> Top10 (control) after different culture timed durations.</p