Preparation of M@BiFeO3 Nanocomposites (M = Ag,Au) Bowl Arrays with Enhanced Visible Light Photocatalytic Activity

High surface area BiFeO₃ (BFO) bowl arrays photocatalyst loaded with different size noble metal nanoparticles were successfully prepared by combining templates method and thermal evaporation followed by heating. The structural and optical properties of the BiFeO₃ bowl arrays and the composite M@BFO bowl arrays (M = Ag, Au) were comparatively characterized. The composite M@BFO bowl arrays showed much higher photocatalytic performance than the pure BFO bowl arrays. The enhanced photocatalytic property of the composite structure could be ascribed to the enhanced near‐field amplitudes of localized surface plasmon of the noble metal nanoparticles which boost the separation of electron–hole pairs and the transfer mechanism of electrons.     

Design and Synthesis of CdWO4:Sb3+ Phosphor Based on sp Energy Level Regularities of Sb3+ Ion

Sb³⁺‐activated CdWO₄ phosphors were designed according to sp energy levels regularities of Sb³⁺ ion in some inorganic compounds. The sp energy levels regularities of Sb³⁺ in dozens of compounds were established with the aid of the dielectric theory of the chemical bond for complex crystals: E_A = 6.2187?1.7584h_e, E_B = 7.019?1.957h_e, E_C = 7.259?1.964h_e. Environmental factor h_e of Cd site was calculated to be 1.6583 with the refined crystal structure and refractive index of CdWO₄:Sb³⁺. Sb³⁺‐doped CdWO₄ was synthesized through a precipitation method and its structure was refined with the General Structure Analysis System. The transition energy of A band of Sb³⁺ in CdWO₄ can be predicted to be 3.312 eV (374 nm), according to the relationship equation between E_A and environmental factor h_e. By monitoring the 521 nm emission band, the excitation spectrum gives a weak excitation band peaking at 355 nm, which was assigned to the ¹S₀–³P₁ transition of Sb³⁺ according to our prediction. Thus, Sb³⁺‐doped CdWO₄ phosphor was designed and synthesized successfully based on sp energy levels regularities of Sb³⁺ ion. This work is a great help to understand the spectroscopy of Sb³⁺ ion and will be useful for the design and development of Sb³⁺‐doped phosphors for applications.     

N‐halamine‐modified polyglycolide (PGA) multifilament as a potential bactericidal surgical suture: In vitro study

In this study, new cationic homopolymer and anionic copolymer were synthesized, and deposited onto polyglycolide sutures using a layer‐by‐layer assembly technique. The coated sutures were rendered antibacterial by chlorinating with dilute solution of household bleach solution at pH 7. The chlorination treatment transformed the N? H groups of anionic copolymer into N‐halamine structures. The N‐halamine‐modified sutures were challenged with Staphylococcus aureus and Escherichia coli O157:H7 bacteria at different contact times. The suture with chlorine loading of 0.22% completely inactivated both bacterial strains in 30 min contact time. Fourier transform infrared spectroscopy, scanning electron microscopy, and analytical titration confirmed the successful deposition of the N‐halamine multilayers. The effect of layer‐by‐layer coatings of polyelectrolytes on the chlorine loading and antibacterial efficacy of sutures was evaluated. The straight‐pull and knot‐pull strength tests performed on the sutures reported slight decline in tensile properties after chlorination treatment. The in vitro hemolysis and cytocompatibility tests revealed that the N‐halamines‐based antibacterial sutures were biocompatible. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42483.     

Diffusion bonding of TiAl based alloy to Ti–6Al–4V alloy using amorphous interlayer

Powder metallurgical TiAl based alloy and Ti–6Al–4V (TC4) alloy were diffusion bonded at 915 °C for 1 h under a pressure of 80 MPa. Single Ti‐based amorphous or Ni‐based amorphous foil was utilized as an interlayer during diffusion bonding process. The tensile mechanical properties of the diffusion bonded joints between TiAl based alloy and TC4 alloy were tested. The fracture surface and microstructure characteristic of these joints were also observed carefully by scanning electron microscope. The TiAl based alloy with a fully lamellar microstructure is more suitable for diffusion bonding to TC4 alloy. Adding a Ti‐based amorphous interlayer is more conducive to the element diffusion, giving rise to the improvement in the mechanical properties of the diffusion bonded joints. Results also show that the diffusion bonded joints form a metallurgical bond and fracture in a brittle manner.