Advanced Materials Research Vols. 236-238

Abstract: An electronic detection method for DNA molecules based on an extended gate field effect transistor (EGFET) sensing chip has been presented in this paper, which consists of one gold plate electrode for molecule recognition and FET part for signal transduction. The DNA probe was prepared by first immobilization of a thiolated single-stranded oligonucleotide (T1) and then an alkanethiol such as 6-hydroxy-1-hexanethiol (6-HHT) on the gold plate. A fast cyclic voltammetry (FCV) was applied to quantification of DNA molecules by using a cathodic peak around -1.3 V at a electrode reaction, corresponding to reductive desorption in strong alkali solution. By using a 70.7 mV DC voltage onto a Ag/AgCl reference electrode, the electronic signals of EGFET were applied to detection of DNA molecules and its hybridization, and the corresponding hybridization efficient was estimated to be about 37.5%. About 1 ~ 4 DNA molecules per 100 nm² on the Au substrate of EGFET could be counted, showing a promising sensing technique for bio-molecule.

Abstract: Nano-sized composite magnetic particles MgO /Fe were in-situ combustion synthesized at 620°Cfor the Mg-70.9wt%Fe3O4 system. In this paper, we discussed the reactant ratio on the influence of micro-morphology and the magnetic properties of nanoparticles. It was indentified that: Mg(29.1wt%) was the suitable reactant ratio, the sintered composite spherical particles with mean diameter 40nm distributed evenly, particles had good soft magnetic properties, and it was the future drug carriers materials.

Abstract: Microchips appear to offer important opportunities for modern research. Microchips based on gold magnetic nanoparticles make manipulation of biomolecules more conveniently, and has the advantage of deducing reaction time. In this study, we first achieved microchips design and fabrication through CO₂ laser ablation for immunoassay, and then conjugated mouse IgG to gold magnetic nanoparticles serve as a target. Finally, HRP labeled goat anti mouse IgG binding assay and substrate reaction were performed with disposable microchips and other devices. The results indicated that the reactions carried on successfully and magnetic particles moved well in chips.

Abstract: The solidification behaviors of titania(TiO₂)-water nanofluid and deionized water (DI water) were investigated using differential scanning calorimetry (DSC) at cooling rates of 1.5—9.0 °C/min. The nanofluid with 0.3 wt% TiO₂ nanoparticles was prepared by dispersing the nanoparticles into DI water. The dispersion and stability was confirmed by a particle size and zeta potential analyzer. Experimental results show that the solidification temperature of the TiO₂-water nanofluid was higher than that of DI water at the same cooling rate. The contact angles of TiO₂ and the interior surface of the sample holder were measured, and the free energy barriers (FEB) of nucleation of the TiO₂-water nanofluid and DI water were calculated. It was found that the FEB of nucleation induced by the TiO₂ nanoparticles was lower than that by the flat surface, resulting in lower supercooling degree.

Abstract: Microstructure and mechanical properties of bulk nanocrystalline Fe₃Al based alloy with 10 wt. % Mn prepared by aluminothermic reaction after annealing at 600, 800 and 1000°C for 8 h were investigated in order to gain insights in effects of annealing. Crystal structure of the alloy did not change and a fiber phase with enriched Mn appeared in the annealed alloy. Grain size of the alloy changed a little after annealing at 600°C but increased a lot after annealing at 800 and 1000°C. The annealed alloy had plasticity in compression at room temperature and the alloy annealed at 1000°C had yield strength of 782 MPa. The alloy without annealing has creep properties in compression at 800 and 1000°C and can be easily hot rolled to strip and sheet.

Abstract: Stable silver nanoparticles were synthesized from AgNO₃ through a simple green route using biodegradable and renewable starch as stabilizing agent. Nanoparticles have been studied for their formation, structure, morphology and size using UV–vis spectroscopy, X-ray diffraction (XRD) and HRTEM analysis. XRD showed that the nanoparticles were of face centered cubic structure. UV–Vis and HRTEM revealed that the spherical particles having radius 5-20 nm are mostly stabilized by starch. Further, antibacterial properties of these starch-stabilized nanoparticles show promising results for S.aureus in growth inhibition ring test.

Abstract: A biodegradable gradient polymeric membrane based on chitosan (CS) and polyvinyl alcohol (PVA) has been prepared by microwave technique. The composition and morphology variation along the thickness direction in membrane were measured by elemental analysis and scanning electron microscope (SEM). The tensile properties of CS/PVA gradient membrane were tested. Results showed that the content of either polymer shows a gradient variation along the thickness direction. SEM photographs exhibit that morphology also evolves gradually with the varying percentage ratio of two polymers. As a result of such variations in composition and structure, the mechanical properties on both sides exhibit a significant difference. Compared with conventional isotropic membrane, gradient membrane has improved mechanical properties.

Abstract: In this paper, the magnesium alloy AZ91D as biological implant material was treated by micro-arc oxidation. The effects on the coating growth of oxidation time and terminal voltages in zirconium solution and silicate solution were investigated respectively. Immersion and electrochemical tests were applied to study the corrosion behavior of AZ91D alloy in Hank’s solution. The results revealed that the coating thickness increases and the corrosion rate in immersion test decreases as the extension of oxidation time and the rising of terminal voltage. The corrosion rate of the alloy in the immersion test treated in zirconium solution varies with the terminal voltages and that in silicate solution depends on the coating thickness. In the polarization curves test, the corrosion current of the MAO treated alloy is two orders of magnitude lower than that of original samples and the polarization curves in zirconium solution show bigger anode and cathode polarizability which indicates that the MAO coating has a strong blocking effect of the corrosion. The corrosion resistance of MAO treated magnesium AZ91D improves significantly.

Abstract: In this article, preparation approach of a novel fluorocarbon nano material was described. The molecule structure, thermal properties and morphology characterization of the fluorocarbon nano material were studied out by Fourier transform infrared spectroscopy (FTIR), thermal gravity and differential thermal analysis (TG-DTA), transmission electron microscope (TEM) and X-ray diffraction analysis (XRD). It was showed that the basic molecule structure of the fluorocarbon nano material was same as the raw material (FKM) except that a new C=C bond was produced in the fluorocarbon nano material at 1624cm^-1. It was demonstrated that the morphology of the fluorocarbon nano material was unattached particles with particle size between 40-60nm under TEM. From TG-DTA curves, it was indicated that the fluorocarbon nano material was high thermal stabile, which oxidizing decomposing temperature in air and thermal decomposing temperature in N₂ were 322°C and 295°C, respectively. The XRD pattern showed that the diffraction peak of amorphous carbon was disappeared when the fluoronano material was baked in air at 350°C, and this result validates the oxidizing decomposing of the fluorocarbon nano material at 322°C of the TG-DTA curve.

Abstract: Scorbyl palmitate is a safty and highly efficient lipophilic antioxidant.It is produced by a novel ionic liquid method: L-ascorbic acid was esterified with palmitic acid to synthesize ascorbyl palmitate,using concentrated sulfuric acid as chemical catalyst in 1-Butyl-3-methy limidazolium terafluoroborate ([BMIM]BF₄).The yield of ascorbyl palmitate reached 69.6±1%.