فصلنامه نانو مواد
پیاپی 24 (زمستان 1394)

In this paper, multi-wall carbon nanotubes (MWCNTs), gold nanoparticles (GNp) and glucose oxidase (GOD) was developed for the specific detection of glucose. MWCNTs were chemically modified with the H2SO4–HNO3 preatreated to introduce carboxyl groups which were used to interact with the amino groups of poly allylamine (PAA) and cysteamine via 1-ethyl-3-(3 dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide cross-linking reaction, respectively. A cleaned Pt electrode was immersed in PAA, MWCNTs, cysteamine and GNp, respectively, followed by the adsorption of GOD, assembling the one layer of films on the surface of Pt electrode (GOD/GNp/MWCNTs/Pt electrode) and was used as working electrodes (anode) along with a platinum auxiliary electrode and the reference electrode Ag/AgCl (cathode). Working electrode was containing the phosphate-buffered saline (PBS) with pH= 4, 6 and 8 enzyme. To evaluate the performance of the constructed biosensor, it was put into a dish containing 0.05, 0.5 and 1 mmol/l (mM) glucose concentrations which were dissolved in doubly distilled water. Glucose concentration and pH design has been tested and analyzed by QUALTEK-4 software measure. According to the performed experiments and software analysis, with increasing concentration, the flow rate of current production is increased and pH deviance from neutral range reduces the flow. Optimal conditions was obtained in concentrations 1 mmol/l and pH=6, respectively. After confirmation tests in optimum conditions, the rate of production was obtained, 21.67 mA, which with respect to the expected error rate of application, it was calculated to be 8.1%. This error rate demonstrates that the accuracy of tests is with high sensitivity and accuracy.

Nanostructured transition metal oxides have received special role in the production of the anode electrode in the lithium-ion batteries. In this research, a one stage method to synthesize Cr2O3/C hybrid microspheres via solvothermal method was reported. The XRD and SEM methods were used for characterization of products. The carbon content of synthesized samples was measured by TGA method. The results showed that only Cr2O3 peaks could be observed XRD patterns, and this indicated that the carbon in the composite was amorphous. The average crystallite size is calculated by using Williamson-Hall, 36 nm. The content of carbon in the composite was 63 wt.%. The SEM images showed that the surfaces of prepared spheres were relatively smooth and carbon microspheres had an average diameter of about 2 μm. The morphologies and sizes of the microspheres change with controlled by reaction conditions solvothermal and in the size range of 0.7-3.5 μm changes.

In this study, nanocomposite Fe/TiO2-shrimpshell as adsorbent was synthesized. Fourier transform spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM) and elemental analysis (EDX) were evaluated and the results showed the Fe3 doped TiO2 nanoparticles and the shell shrimp on Fe/TiO2. Adsorption Malachite green with effective parameters adsorption kinetics, adsorption isotherms and thermodynamic parameters were studied in depth. Based on the experimental results and correlation coefficients, malachite green dye adsorption kinetics pseudo second order and isotherms of Freundlich was adopted. The negative values of standard free energy (ΔG˚) suggest that the adsorption process is spontaneous. The value of enthalpy change (ΔH˚) indicates that the removal process is endothermic.

This paper has focused on the processing, densification and microstructural investigations of hot pressed nano-ZrB2 ultrahigh temperature ceramic, without addition of any sintering aids or reinforcement phases. A design of experiment approach, Taguchi methodology, was used for the statistical analyses of hot pressing parameters (temperature, time and pressure) in order to optimize the densification conditions. The mentioned parameters, each parameter with three levels, were studied in relatively low temperatures/pressures conditions, compared to the previous research works. The relative density of the nano-ZrB2 ceramic reached >92% at the optimized hot pressing conditions, the sintering temperature of 1850 °C, the soaking time of 90 min and the external pressure of 16 MPa. The statistical analyses recognized the hot pressing temperature as the most important parameter and the applied external pressure as the less important factor affecting the densification of nano-ZrB2 ceramic.

Alumina is an inert bioceramic with improved mechanical properties in comparison to hydroxyapatite. It is possible to active the surface of the inert porous alumina. In this research, the surface of alumina scaffolds was activated with surface modification and creating of hydroxyl groups in order to silanization of scaffolds. The crystallinity degree and the lattice parameters and lattice constant and crystallite sizes of inert alumina scaffolds and activated surface one were estimated by XRD patterns. The results revealed that the intensity of peaks has been decreased after surface modification. It means the crystallinity degree has been decreased and the amorphous phase increased. As well, the theoretical calculations showed the crystallinity degree has been decreased from 77% to 66%. The crystal structures and lattice parameters of scaffolds are so close to natural corundum. The chemical structure of the alumina scaffold before and after the hydration process was characterized by FTIR instrument. The SEM images of the alumina scaffolds showed the porosities of the scaffolds are interconnected with appropriate size for bone tissue regeneration.

In this study¡ the effect of diffusion bonding process¡ and the deposition of nano particles reinforcer on microstructure and mechanical properties of nano-composites hybrid layer of nano-ZrO2 and nano-Al2O3 was investigated. First¡ stable suspensions of nanoparticles with different weight percentages were coated on aluminum sheets and scattered. The coated aluminum-sheets were heated at 635-645 C and finally pressure was hot-pressed. Study of microstructure and distribution of nanoparticles were studied by using scanning electron microscopy (SEM) and mechanical properties tests (the tensile strength and micro-hardness). The results showed that the distribution of nanoparticles deposited by suspension and the use of diffusion bonding process leads to a better distribution of reinforcing particles¡ agglomeration increased and mechanical properties reduced. Using of lower temperature range compare to liquid state process caused eliminating of high temperature chemical reaction and decreasing of shrinkage inclusions. Therefore¡ the stability¡ residue nanoparticle increased and tensile strength and micro-hardness of nano-composites improved.