Advanced Materials Research Vols. 399-401

Abstract: Sandwich structures are widely used in the aerospace field, also for primary parts. However, due to the low strength of core properties, the failure behavior under high stress concentration such as joining position is hard to evaluate. This study is, at present, a key task to enable future exploitation of the joint for structural sandwich consisted of Carbon Fiber Reinforced Polymer (CFRP) face and a Honeycomb core made of phenolic impregnated NomexTM paper. Previous experimental investigations provided the failure mechanism of sandwich plates with hard points in the form of inserts, and special attention is focused on the problem of sandwich panels with inserts of the fully potted types. Numerical simulations are achieved in this work with good correlation based on experimental test.

Abstract: This paper describes a new synthesis and separation method of nanoparticles (NPs) using a non-toxic, non-ionic surfactant systems. The purification steps did not use ethanol or acetone. Results indicate that the wild type bovine Carbonic Anhydrase (CA) activity was enhanced almost 4 times more than the CA encapsulated NPs fabricated by the traditional method. The NPs have are more hydrophilic and also have a higher zeta potential. The well dispersed CA PAA NPs with of 10-30 nm in diameter were obtained. This work also demonstrates a universal method for immobilizing fragile biomacromolecules in NP carriers for biomedical applications.

Abstract: New inorganic pigments Ce_0.95Zr_xPr_0.05-xO₂ (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05) based on CeO₂-ZrO₂-Pr₆O₁₁ solid solutions were synthesized by low-temperature combustion synthesis (LCS) method using citric acid as a reductant and metal nitrate as an oxidant. The pigments are CeO₂ solid solutions doped with praseodymium and zirconium ions, and display colors ranging from dark brown via brick red to bright cream. The prepared pigments were characterized by X-ray powder diffraction, transmission electron microscopy, ultraviolet-visible absorption spectroscopy and colorimetrical measurements. Results show that cubic fluorite structure solid solution of 100 nm Ce_0.95Zr_xPr_0.05-xO₂ particles can be obtained at 1000 °C. There was an effective absorption of visible blue and green in 600 nm, which is originated from the shift of charge transfer band in CeO₂ by doping of zirconium and praseodymium ions. Effective red hue was obtained for Ce_0.95Zr_0.02Pr_0.03O₂ composition, which exhibited better L*, a*,and b* values (57.64, 23.83 and 23.78). The coloring mechanism is based on the introduction of an additional electronic energy level of unpaired 4f electron of the lanthanide ion into the cerianite forbidden band. Furthermore, the doping of Zr in Pr-CeO₂ system raises the slope of the absorption edge with a blue shift resulting in enhanced lightness. The prepared pigments were prospective to be alternatives for toxic pigments used in coloration of plastics.

Abstract: Mesoporous anatase-TiO₂ nanoparticles mono-doped and co-doped with thulium and nitrogen were synthesized via a modified sol-hydrothermal method, and characterized by XRD, BET, XPS, FT-IR, DRS and PL techniques. The results showed that the Tm-doping inhibited both the transformation from anatase to rutile phase and the recombination of photogenerated electron-hole pairs, as well as increased the content of surface hydroxyl group, then improved the UV photoactivity of TiO2. The N-doping led to forming the N–Ti–O and N–O–Ti structures, which narrow the electronic band structure, then improved the photoactivity in the visible light region. However, the best visible light photoactivity for degradating methylene blue (MB) in aqueous solution was obtained in the N-doped sample instead of the co-doped sample, implying that no synergetic effect rises from Tm and N co-doping.

Abstract: The silver nanoparticles with 42 nm in diameter were synthesized under control of cetyltrimethyl ammonium bromide (CTAB). CTAB acted not only as reactant but also as dispersing agent. The efficient molluscicidal effect of the silver nanoparticles showed that a new way of the schistosomiasis prevention has been explored.

Abstract: TiO₂ nanomaterials were synthesized in lyotropic liquid crystal formed by nonionic surfactant TritonX-100 and TiOSO₄ aqueous solution with NH₃•H₂O as precipitator. The lyotropic liquid crystals were characterized by means of POM and Low-angle XRD. FT-IR, TGA, XRD, TEM were used to characterize the TiO₂ samples. It was found that all the lytropic liquid crystal were in lamellar liquid crysal phase and after casting the micro-structure of the LLC phase, the TiO₂ samples were self-assemble to form lamellar, sphere and rod structures. According to the characterization results, possible formation mechanism was proposed.

Abstract: Silver (Ag) semishells arrays were fabricated with a seed-mediated growth method by depositing silver films on top of self-assembly close-packed monolayer of SiO₂ nanoparticles. The surface morphologies and optical properties were characterized using TEM, SEM and UV-Vis spectroscopy. The surface-enhanced Raman scattering (SERS) activities of these nanostructures were investigated using methylene blue (MB) as probe molecule. The enhancement factor was estimated to be as large as 2.05×10¹⁰. The results revealed that these Silver nanostructures are good SERS-active substrates.

Abstract: Antimony doped tin oxide (ATO) nanoparticles were synthesized via complex-homogeneous coprecipitation. Then different drying methods (such as azeotropic distillation, infrared drying and microwave drying, etc.) were used to eliminate the agglomeration. The nanoparticles were characterized by thermal analysis, X-ray diffraction (XRD), and Brunauer-Emmett-Teller measurements (BET). The result shows that ATO nanopaticles with tetragonal rutile phase structure are all well crystallized after the drying processes above, and the average grain size is between 29.30 nm and 71.52 nm. The grain size estimated by BET method is similar to the result of Scherrer equation, and the nanoparticles prepared by azeotropic distillation have better crystallinity comparing to other methods. With the extension of the distillation time, the grain size increases, and the colour changes from grey blue to light grey. Moreover, the combination of azeotropic distillation and infrared drying can prepare smaller and better crystalline ATO nanoparticles.

Abstract: Titania nanotube films were produced by anodization of titanium foil. The titania nanotube films were annealed at different temperatures. Morphology evolution, phase transformation and electrical conductivity of the titania nanotubes were studied. Results showed that the nanotube walls became rough, porous and even collapsed after annealed at 400, 500 and 600 °C respectively. Titania anatase phase formed after annealed at 400 °C; the amount of anatase phase increased as the annealing temperature increased. The conductivity of the nanotube film annealed at 400 °C was improved greatly compared with the conductivity of the as-anodized nanotube film. However, the conductivity of the nanotube films annealed at higher temperatures decreased. The effect of the morphology on the electronic conductivity of the titania nanotube films was discussed.

Abstract: A simple solid-phase synthetic approach has been exploited for the preparation of Ni-carbon sphere composites using Ni(CH₃COO)₂•4H₂O as nickel source, and vitamin C (L-ascorbic acid) as reductant and carbon source at 500oC for 6 h. The products were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray energy dispersive spectrometer (EDS), raman spectroscopy and microwave-absorbing measurement. The results show that the products are composed of Ni-carbon sphere particles with average diameters of 1.2 µm. Each sphere particle contains embedded Ni particles with average diameters of 83 nm. The reflection loss (RL) values of the products are lower −10 dB at 2–18 GHz, displaying broad range of microwave absorption. Their minimum RL value is about −33 dB at 4.2 GHz, which exhibit good microwave absorbing properties.