Cavitation Bubble Behavior Near Solid Boundaries

In the present study the bubble behavior in the narrow space are experimentally and numerically examined as the gap between two parallel walls and the position of bubble induction were changed. The main results are as follows. (1) The effects of two parallel walls can be classified by the ratio of the gap between the walls to the maximum bubble radius. If the ratio>5.0 the bubble shape is almost sphere. The wall effect remarkably appears for the ratio<3.0 and the bubble deforms to be dumbbell- or cone-like shape. (2) When the gap between the walls is small, the single bubble is finally divided into two bubbles owing to the large lateral pressure. The rebound of each bubble causes impulsive pressure and damages the upper and lower wall surface. Especially, if the bubble is not created at the center between the walls, the collapse phase shift among the divided bubbles brings the further damage on the wall surface. (3) The computed motion of the bubble without non-condensable gases well explains the dumbbell- or cone-shaped bubble deformation

Synthesis and Atomic Characterization of a Ti₂O₃ Nanosheet

Titanium oxide nanosheets have been attracting much attention owing to their photocatalytic property. Here, we synthesized a Ti₂O₃ nanosheet by the reduction of a titania nanosheet (Ti_0.87O₂) that was one or two atoms in thickness. The atomic structure of the Ti₂O₃ nanosheet was quantitatively revealed by electron diffraction analysis, electron energy-loss spectroscopy, and high-resolution transmission electron microscopy (TEM). A titania nanosheet (Ti_0.87O₂) consisting of edge-shared TiO₆ octahedra was transformed to a Ti₂O₃ nanosheet consisting of face-shared octahedra by electron beam irradiation. This represents a stable crystal phase of titania nanosheets like the Magneli phase in oxygen-deficient environments. The atomic arrangement of the Ti₂O₃ nanosheet was directly observed by newly developed aberration-corrected TEM

Correction to “Synthesis and Atomic Characterization of a Ti₂O₃ Nanosheet”

Correction to “Synthesis and Atomic Characterization of a Ti₂O₃ Nanosheet

Exfoliated ferrierite-related unilamellar nanosheets in solution and their use for preparation of mixed zeolite hierarchical structures

[Image: see text] Direct exfoliation of layered zeolites into solutions of monolayers has remained unresolved since the 1990s. Recently, zeolite MCM-56 with the MWW topology (layers denoted mww) has been exfoliated directly in high yield by soft-chemical treatment with tetrabutylammonium hydroxide (TBAOH). This has enabled preparation of zeolite-based hierarchical materials and intimate composites with other active species that are unimaginable via the conventional solid-state routes. The extension to other frameworks, which provides broader benefits, diversified activity, and functionality, is not routine and requires finding suitable synthesis formulations, viz. compositions and conditions, of the layered zeolites themselves. This article reports exfoliation and characterization of layers with ferrierite-related structure, denoted bifer, having rectangular lattice constants like those of the FER and CDO zeolites, and thickness of approximately 2 nm, which is twice that of the so-called fer layer. Several techniques were combined to prove the exfoliation, supported by simulations: AFM; in-plane, in situ, and powder X-ray diffraction; TEM; and SAED. The results confirmed (i) the structure and crystallinity of the layers without unequivocal differentiation between the FER and CDO topologies and (ii) uniform thickness in solution (monodispersity), ruling out significant multilayered particles and other impurities. The bifer layers are zeolitic with Brønsted acid sites, demonstrated catalytic activity in the alkylation of mesitylene with benzyl alcohol, and intralayer pores visible in TEM. The practical benefits are demonstrated by the preparation of unprecedented intimately mixed zeolite composites with the mww, with activity greater than the sum of the components despite high content of inert silica as pillars

Undoped Layered Perovskite Oxynitride Li₂LaTa₂O₆N for Photocatalytic CO₂Reduction with Visible Light

Oxynitrides are promising visible‐light‐responsive photocatalysts, but their structures are almost confined with three‐dimensional (3D) structures such as perovskites. A phase‐pure Li₂LaTa₂O₆N with a layered perovskite structure was successfully prepared by thermal ammonolysis of a lithium‐rich oxide precursor. Li₂LaTa₂O₆N exhibited high crystallinity and visible‐light absorption up to 500 nm. As opposed to well‐known 3D oxynitride perovskites, Li₂LaTa₂O₆N supported by a binuclear Ruᴵᴵ complex was capable of stably and selectively converting CO₂ into formate under visible light (λ>400 nm). Transient absorption spectroscopy indicated that, as compared to 3D oxynitrides, Li₂LaTa₂O₆N possesses a lower density of mid‐gap states that work as recombination centers of photogenerated electron/hole pairs, but a higher density of reactive electrons, which is responsible for the higher photocatalytic performance of this layered oxynitride