Solid State Phenomena Vol. 294

Abstract: In this paper, the deposition and optical properties of charge-stabilized gold nanoparticles on silicon oxide substrates is studied, which have been derivatised with (aminopropyl) triemethoxysilane. Monodispersed charged-stabilized colloidal gold nanoparticles with diameters between 20-150 nm were prepared and their self-assembly and optical properties on silica substrates is studied. Atomic force microscopy (AFM) is employed to investigate the nanoparticle monolayers ex situ. Analysis of AFM images provide evidence that the formation of the colloidal nanoparticle monolayers is governed by random sequential adsorption. The results indicate that the ionic strength of the suspension influences the spatial distribution of the nanoparticles. For all sizes of the Au nanoparticles tested, optical simulations of extinction coefficients made by finite-difference time domain (FDTD) indicate a resonance peak in the range of 510-600 nm wavelength of the visible range of the electromagnetic spectrum. The results indicate a simple and inexpensive approach of assembly of plasmonic nanostructures that can find applications in metamaterials and light waveguides.

Abstract: The hen egg shells (HES) from EnShi, HuBei Province, China, which contain selenium, are used as adsorbent for the adsorption of lead ion from its aqueous solutions. The selenium in the HES could help to remove lead from its aqueous solution. The HES had been found to be the more efficient in the experiment and removed about 95% of lead from its aqueous solution. The final concentration of lead ion was found lower than the waste water quality standards from the initial concentration of lead ion 100.0 mg/L through these two steps of adsorptions. One gram of the HES can adsorb nearly 31.71±0.040 mg of lead ions. The adsorption kinetics was fitted by first-order model throughout the period. The present adsorption process is spontaneous, indicating HES can be availably used for the removal of lead ions from its aqueous solution.

Abstract: This paper reports on the synthesis and application of Fe₃O₄/TiO₂ nanocomposite. In situ attachment of TiO₂ coating to the surface of the magnetic nanoparticles (Fe₃O₄) was attained by direct condensation of titanium precursors. Characterization result suggests that the average particle size of the synthesized nanocomposite is 10-15 nm. Also, FT-IR result confirms the presence of TiO₂ layer in the surface of the magnetic nanoparticles. Furthermore, the prepared Fe₃O₄/TiO₂ nanocomposite was utilized as an active magnetic nanophotocatalyst for the degradation of cyanide. Results show that even at 5.0 mg of Fe₃O₄/TiO₂ photocatalyst, higher cyanide removal efficiency (91%) was obtained when 60 ppm CN^- was incubated with the photocatalyst for 30 minutes. Likewise, it has been demonstrated that the synthesized magnetic nanophotocatalyst can be used to degrade cyanide using sunlight as the natural light source. A 94% cyanide removal efficiency was obtained when the sample was incubated with the synthesized magnetic nanophotocatalyst for 120 minutes under sunlight irradiation. Importantly, the prepared magnetic photocatalyst can be re-used several times (up to 5 cycles) without significant changes in the cyanide removal efficiency.

Abstract: This paper aims to present the characteristic of dewatered sewage sludge (SS) and red gypsum (RG) to determine their recycling potentials into a valuable product. The materials were characterized based on their physical-mechanical-chemical properties and morphology. The results showed that dewatered sewage sludge and red gypsum could complement each other when used together to form a new material the merits of which will be investigated in subsequent studies. RG has a better performance in term of plasticity and strength than SS due to fines content in the former and therefore its ability to retain moisture that contributes to cohesion between particles. Fine prisms and closer packing particles add strength in RG leading to higher resistance in compression. Unlike RG, SS has coarser particle and more voids causing it to lose the moisture content and becomes easily disintegrated. Chemical compositions of RG and SS as determined by XRF demonstrated a significant amount of CaO in the former and SiO₂ in the latter; the formation of hydrated products in the form of CSH and CAH gel from hydration or pozzolanic reaction contributes to strength improvement of the SS.

Abstract: We report on the growth of zinc oxide/polyaniline (ZnO/PANI) nanocomposites deposited on platinum (Pt)–coated glass substrate via chemical bath deposition and dip–casting technique is reported. Scanning electron micrographs of the nanocomposites revealed that etching of ZnO nanorods takes place during growth which turn into plate–like and distorted nanostructures. We found out that increasing the concentration of NH₄OH triggered increase in nanostructure diameter. The surface morphology of nanocomposites significantly changed as the molar concentration of NH₄OH precursor varies. Fast fourier transform infrared spectroscopy results showed the interaction of ZnO and PANI by observing the shift of peaks to the higher wavenumbers. The measured optical band gap of the nanocomposites are in good aggreement with the reported values. This result indicates that the grown ZnO/PANI nanocomposites is a good material for solar cell device.

Abstract: We report on antibacterial activities of Zinc oxide (ZnO) with different structures. Fast furrier transform infrared spectroscopy ZnO nanostructures showed peaks in the range between 450–600 cm-1 indicating the successful growth through the presence of Zn-O stretching. On the other hand, impurities such as zinc complexes might be present due to the appearance of peaks at 1110 cm-1, 1390 cm-1 and 1506 cm-1. Furthermore, SEM images revealed that nanorods and sea-urchin like nanostructures are present in the produced ZnO nanostructures. Nanorods exhibit a better antibacterial response than the sea-urchin like structure. The change in structural morphology along with its purity has greatly influenced the area of bacterial inhibition zone during antibacterial testing.

Abstract: A series of Sm_0.5Sr_0.5CoO₃-CeO₂ ceramics formed by solid state-reaction method have been systematically investigated. The effects of doping the Sm site of Sm_0.5Sr_0.5CoO₃ with Ce⁴⁺ on the structural, spectral reflectance, and thermal radiation properties were also explored. The modification of the initial phase takes place can be ascribed to the dissolution of Ce from initial CeO₂ into the perovskite structure. The conductivity behavior depends critically on the Ce doping level, as was demonstrated that the recombination of holes (from Sm_0.5Sr_0.5CoO₃) and electrons (from ceria ion) could decrease electrical conductivity. Sm_0.5Sr_0.5CoO₃-CeO₂ ceramics showed continuously adjustable conductivity and infrared emittance, opening up possible applications in solar thermal conversion or thermosensitive conductivity.

Abstract: Honeycomb absorbing materials are anisotropic structural materials. Depending on the size of honeycomb lattices, the absorbent content of the impregnated layer is different, the thickness of the impregnated layer is different, and the absorbing function of the impregnated honeycomb absorbing materials is also different. For the characterization of electromagnetic parameters of honeycomb absorbing materials, this paper adopts free space method for testing, uses CST software for modeling, and inverts the electromagnetic parameters of honeycomb absorbing structures. The absorbing performance of single-layer and double-layer honeycomb sandwich structures was simulated by RAM Optimizer software. The research shows that the height of the single-layer honeycomb absorbing material is 22mm. When the absorber content is 65%, 75% and 85% respectively, the harmonic peak moves slightly to the low frequency electromagnetic wave with the increase of the absorber content, but the absorbing strength decreases with the increase of the absorber content. For the double-layer honeycomb sandwich structure, the difference of absorber content in the upper and lower honeycomb absorbing materials is smaller, and the absorbing performance is stronger. When the thickness of the wave-transparent panel is thinner, the harmonic peak of the absorbing curve moves slightly to the high frequency.

Abstract: Objectives: The aim of the study was to evaluate monomer elution from three commercial orthodontic adhesive pastes. Methods: Three monomers BPA, Bis-GMA, and TEGDMA were observed from Green Glue (Hangzhou Westlake Biomaterials Co., Zhejiang, China), GrenGloo (Ormco Co., Glendora, CA, USA), and Transbond XT (3M Unitek, St. Paul, MN, USA). The adhesive was light-cured in a cylindrical mold with 6 mm in diameter and 2 mm thick, before immediately immerse into 10 ml extraction media of 75%ethanol in a tightly sealed container at 37°C. The solution was refreshed at four intervals of time 1, 3, 5, and 7 d. The immersion medium was determined using High-performance liquid chromatography (HPLC). Results and Conclusions: BPA were found from three adhesives. Bis-GMA was found only from Transbond XT. TEGDMA were found from both Green Glue and Grengloo. Green Glue had 10-30 times higher TEGDMA elution than Grengloo. Major elution was found from all orthodontic adhesive paste within 1 d, and decrease with time to 7 d.