Advanced Materials Research Vol. 1088

Abstract: Results of researches of structure and properties of the nanostructured carbon coatings deposited on a polyurethane substrate are presented in article. Possibility of application of the scanning probe microscope methods and sklerometry for quality control of the nanostructured carbon coatings is shown. The results of researches showing are given that the nanostructured carbon coatings deposited on polyurethane have high degree of adhesion to a substrate, reduce porosity of surface and increase its durability and wear resistance, increase elasticity and coefficient of elastic restoration at deformation.

Abstract: MWCNTs were dispersed in acetone solution of styrene-acrylonitrile copolymer (SAN). Four factors which had effect on the average particle size, including the ratio of MWCNTs to SAN, the mass percent of MWCNTs, the ultrasonic power and the ultrasonic time, were studied. The optimal dispersion conditions of MWCNTs in acetone solution of SAN were the ratio of MWCNTs to SAN 1:3, the mass percent of MWCNTs 0.25%, the ultrasonic power 100%, and the ultrasonic time 30 min.

Abstract: Multi-walled carbon nanotubes (MWCNT) were used as an efficient adsorbent to remove Paraquat (PQ) molecules from its aqueous solutions. The initial PQ concentration, adsorption time and temperature had considerable effect on the removal of PQ onto MWCNT. The adsorption of PQ onto MWCNT followed the pseudo second-order kinetic model involving the particle-diffusion mechanism. The adsorption isotherms were fitted by the Langmuir isotherm, with the maximum adsorption capacity based on the former of 79.365 mg·g-1. Thermodynamic parameters, including Gibbs free energy changes (ΔG0), as well as changes in enthalpy (ΔH0) and entropy (ΔS0), were also calculated. The results demonstrated that PQ was adsorbed onto MWCNT spontaneously and endothermically in nature.

Abstract: In this work, nanostructured magnesium oxides were formed by PEO process on cast pure magnesium and the tensile properties of thin (5.8 μm) and thick (11.2 μm) coated samples were evaluated. The results obtained by uniaxial tensile testing show that the thin PEO coating had very little effect on the ultimate tensile strength (UTS) and elongation of the cast pure magnesium, while its yield strength was somewhat decreased. For the thick coated sample, both the yield strength and UTS decreased considerably, but the variation of the elongation was moderate, compared to the uncoated sample. The microstructures characterized by SEM revealed that the high porosity content and the large size of pores in the thick PEO coating should be responsible for the significant reduction in the properties of cast pure magnesium. The relationship between the tensile properties and microstructure of the PEO coated samples suggests that the thin PEO coating should be selected to protect the pure magnesium for biodegradable applications.

Abstract: Composite nanostructures of NaYF₄:Yb³⁺, Er³⁺@Au have been successfully prepared by attaching gold nanoparticles onto the surface of NaYF₄: Yb³⁺, Er³⁺ upconversion nanoparticles (UCNPs). NaYF₄ inert shell was used to adjust the separation distance between gold nanoparticles and UCNPs. Effects of the gold nanoparticles on their upconversion luminescent (UCL), temperature sensing and photothermal therapy properties were systematically investigated. For all samples, a slight decrease of the UCL intensity was observed after gold nanoparticles attachment, suggesting that the nonradiative quenching effect is the dominant interaction between UCNPs and gold nanoparticles. However, the reduction of the UCL intensity is negligible due to the significant improvement of UCL properties by NaYF₄ shell. In addition, the gold attachment can obviously improve the photothermal conversion effect, but do not affect the temperature sensing properties of NaYF₄:Yb³⁺, Er³⁺ UCNPs, indicating their high capability for multifunctional applications in biomedical fields.

Abstract: Dendrimer used as template which can better control the size, shape and dispersion of the rare metal nanoparticles. In this paper, we comparatively studied the nanocomposites of the polyamidoamine dendrimer PAMAM/RE and hyperbranched poly (amine-ester) HPAE/RE (RE=La, Nd, and Eu) based on the molecular dynamics simulation method. It was theoretically discussed the feasibilities of the PAMAM and HPAE as templates, the results show that the system energies decreases and tends to be stable after the compositions of the template molecules PAMAM and HPAE with the rare metal atoms (La, Nd, and Eu). Among them, changes of bond stretching, bond angle bending energy and van der Waals play a key role to the potential changes. The radiuses of gyrations of the composite systems are all smaller than the corresponding template molecules. The molecular dynamic information obtained by using of molecular simulation can not only make a reasonable explanation for the macroscopic experimental phenomena, but also greatly promote the development and application of the dendrimers.

Abstract: CdS quantum dots/ Boron and Nitrogen co-doped TiO₂ photocatalyst emulsions were synthesized by a complexation-controlled hydrolysis method at room temperature. Boron compounds and Nitrogen compounds were added to TiO₂ precursor solution, and CdS quantum dots were attached to TiO₂ particles surfaces by using chemical reaction. The hybird composite photocatalysts were characterized by XRD, UV-Vis. Their photocatalytic properties were evaluated through the degradation of acid red 3R dye. The results indicate that when TiO₂ emulsion add to Boron ions, Nitrogen ions, and CdS quantum dots, the photocatalytic performance of the emulsion is the best.

Abstract: The idea of preparing the surface of chitosan layer pre-absorbed on the monodispers porous microsphere via layer by layer approach receives special relevance in enzyme technology. Moreover, the colloidal stability is not impeded by the adsorbed proteins despite the fact that up to 390.2 mg of enzyme adsorbed per gram of the carrier particles. Maximum relative activity was observed at 50 °C and pH 3.5. The activity half lives for native and bound states of enzyme were found as 14.27 d and 31.05 d, respectively. These particles, premodified with the layer of magnetic nanoparticles to impart the magnetic property, were repeatedly used as catalysts following their rapid and easy separation.

Abstract: Use of the noble metal nanoparticles in the surface-enhanced resonance Raman spectroscopy (SERRS) is a significant part the measurement. These nanoparticles are often used for SERRS measurements of silver nanoparticles prepared by reduction methods. From the literature it is obvious that the most popular methods of preparation of Ag nanoparticles are procedures which are using the chemical reduction and/or laser ablation. In this paper we discuss the comparison of SERRS spectra of water-soluble porphyrins (TTMAPP and TMPyP) in systems with Ag nanoparticles prepared by chemical reduction with sodium borohydride, sodium citrate and glucose. The comparison of different systems gives insight into the option of suitableility of using of nanoparticles with various surface ions in the production of different spectral forms of chosen porphyrins in dependence on their structures.