Advanced Materials Research Vol. 787

Abstract: Charge trapping properties of Au nanocrystals (NCs) with various sizes and densities embedded in metal oxide semiconductor (MOS) were investigated. Comparing with the Nc size, experimental results show that the NC spacing is more influential in electron trapping. Au NCs with the size of 8~13nm have larger memory window than the Au NCs of 13-17nm and 6-8nm, which can be ascribe to the higher field-enhancement effect caused by the larger NC spacing. Optimized NC size can improve the specific characteristic of memory device effectively.

Abstract: Ordered Co-Ni nanowires have been fabricated by alternating current (AC) electrodeposition method using anodic porous alumina as a template. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) test results reveal that the samples are polycrystalline with uniform diameters around 50 nm and lengths up to several micrometers. X-ray diffraction (XRD) pattern indicate the crystalline structure change from fcc to hcp as the Co composition increasing. Magnetic measurements show that the nanowires have high magnetic anisotropy with their easy axis parallel to the nanowire arrays. The coercivity (H_c) and squareness (M_r/M_s) are found to increase with the increase of ferromagnetic Co component.

Abstract: The article describes prospective composite biocompatible titania coatings modified with hydroxyapatite nanoparticles and obtained on intraosseous implants fabricated from commercially pure titanium. Consistency changes of morphological characteristics and crystalline structure, mechanical properties and biocompatibility of experimental titanium implant coatings obtained by the combination of oxidation and surface modification with hydroxyapatite during induction heat treatment are defined.

Abstract: A facile low-cost non-vacuum process for fabrication of high quality CuInSe₂ (CIS) films is described, which indicates a promising way for the application in thin film solar cells. First, citrate-capped Cu₁₁In₉ alloy nanoparticles are synthesized by hot-injection method after a system research on the different reaction time and Cu-In ratio of the raw materials. From the TEM and XRD results, we can see that uniform spherical nanoparticles with dominant Cu₁₁In₉ phase and less particle-to-particle agglomeration are successfully achieved in this study. Then, employing spray and RTP selenization process, high quality CIS films with dense and big grains are obtained, which show the single chalcopyrite structure and the preferred (112) orientation. An energy band gap about 1.01 eV is measured through the absorption spectroscopy measurement in our work.

Abstract: The nanocrystalline FeCoNbB films are made by magnetron sputtering. The magnetization saturation of the filmes increase with the film thickness. The complex permeability spectra of the samples vary with the thickness of the film as well. The relaxation frequency is much higher than that of FeCoNbB ribbons because of magnetocrystalline anisotropy. The amplitude of the real part of the permeability decreases with the rising thickness of the film. This phenomenon suggest that the random anisotropy theory is to somewhat applicable for thin films. The X-ray diffraction pattern and the shape of the hysteresis loop show the crystal grains grow with the increase of the film thickness and also result a deterioration in magnetic softness.

Abstract: In 6 mol/L HCl medium, TeO₄^2- is reduced by NaH₂PO₂ to Te that catalyze NaH₂PO₂ reducing HAuCl₄ to form gold nanoparticles (AuNPs), which exhibited a strong resonance Rayleigh scattering (RRS) peak at 370 nm. With the TeO₄^2- concentration increased, the catalytic reaction enhanced and formed more AuNPs that resulting in the RRS peak increased. Under the chosen conditions, the RRS intensity at 370 nm enhanced linearly with the concentration of TeO₄^2- in the range of 12.5-287.5 nmol/L. This RRS method was sensitivity, selectivity, and simplicity.

Abstract: In the HCl medium of 0.90 mol/L, Se (IV) was reduced by NaH₂PO₂ and generated selenium nanoparticles, and there is a resonance Rayleigh scattering (RRS) peak at 588 nm. Under the selected conditions, with the increased of Se (IV) concentration, generated selenium nanoparticles increased, the resonance Rayleigh scattering peak intensity (ΔI_588nm) at 588 nm was increased, and the ΔI_588nm had good linear relationship to Se (IV) concentration in the range of 0.1-1.5 mg/L, with a linear regression equation of ΔI_588nm= 489.9C + 9.0, the detection limit of 12.0 μg/L.

Abstract: Hemin aptamer was used to modify gold nanoparticles (AuNPs) to obtain a stable aptamer-nanogold probe (AussDNA). In the condition of pH 8.0 Tris-HCl buffer solution containing 50mmol/L NaCl, the substrate chain of AussDNA was cracked by hemin to produce a short single-stranded DNA(ssDNA) and then further combined with hemin to form a stable hemin-ssDNA conjugate. The AuNPs released from AussDNA would be aggregated in the condition of 50mmol/L NaCl and exhibited a strong resonance Rayleigh scattering (RRS) peak at 368nm. Under the selected conditions, the increased RRS intensity (ΔI_368nm) was linear to hemin concentration in the range of 5-750nmol/L, with a detection limit of 66 pmol/L. This RRS method was applied to determination of residual hemin in serum samples, with satisfactory results. The remnant AussDNA in the solution exhibited a strong catalytic activity on the gold particle reaction of HAuCl₄-vitamine C (VC) that can be monitored by RRS technique at 368 nm. When the hemin concentration increased, the AussDNA decreased, the catalysis decreased, and the RRS intensity at 368nm decreased. The decreased RRS intensity ΔI_368nm was linear to the hemin concentration in the range of 1-200nmol/L, with a detection limit of 54 pmol/L. Accordingly, a sensitivity, selectivity, and simplicity new method of resonance Rayleigh scattering spectra to detect hemin using aptamer-modified nanogold as catalyst was established.

Abstract: Nanoparticles are presently being studied for optical and biomedical applications such as medical imaging and drug delivery. Nanoparticles impact the cellular environment due to many variables such as size, shape, and composition. How these factors affect cell viability is not fully understood. The purpose of this study is to test the toxicity effects of silver coating (Ag@) Barium Titanium Oxide (BaTiO₃) nanoparticles on Rhesus Monkey Retinal Endothelial cells (RhRECs) in culture. The addition of silver to the nanoparticles increases their nonlinear optical properties significantly, making the Ag@BaTiO₃ nanoparticles good candidates for nonlinear microscopy contrast agents. We hypothesize that by silver coating nanoparticles, there will be an increase in cell viability at higher concentrations when compared to non-silver coated nanoparticles. RhRECs were treated with BaTiO₃ and Ag@BaTiO₃ at concentrations of 0, 1.0, 10.0, and 100μg/ml for 24 hours at 370C + 5%CO₂. After 24 hour incubation with respective nanoparticles, cell viability was determined using the trypan blue dye-exclusion method. Treatment with 0, 1.0 and 10.0μg/ml of Ag@BaTiO₃ had minimal effect on cell viability, with 90% viable cells remaining at the end of the 24 hours treatment period. However, cells treated with 100μg/ml of Ag@BaTiO₃ resulted in a decrease to 51% viable cells. Comparatively, cells treated with 0, 1.0 and 10μg/ml of BaTiO₃ had no significant effect on cell viability (90% viable cells after treatment) while the 100μg/ml treatment resulted in a decrease to 29% viable cells. These results show that silver coating of BaTiO₃ nanoparticles has a protective effect on cellular toxicity at high concentrations.

Abstract: Two kinds of polyester bis (p-hydroxybenzoic acid) butanediolatepolyester (BDPET) and bis (p-hydroxybenzoic acid) diethylene glycol (DGPET) were synthesized through melting transesterification reaction.Then the epoxy resins were modified with BDPET or DGPET,and nanoTiO₂. The composites were characterized by DSC and SEM. The experimental results showed that the polyester can act as an effective toughening modifier for the epoxy resin. The mechanical properties of the composites were greatly improved and reached to the maxium at 4wt.%PET. The PET/EP system modified by adding suitable amount of nanoTiO₂ have better performance.The glass transition temperature (Tg) of PET/EP and nanoTiO₂/PET/EP system improved about 20°Cand 27.8°C,respectively.