Advanced Materials Research Vol. 486

Abstract: The electrospinning technique was used to prepare the Polyethylene Terephthalate (PET) mats. The electrospun PET mats with different fiber diameters have many applications such as biotechnological and biomedical, functional coating, lithum-ion membrane and filtering membrane and so on. Several techniques including scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and single fiber electronic tensile strength tester were used to characterize the electrospun PET mats before/after thermal treatment. When choosing the suitable temperature, the thermal treatment could improve the tensile properties without damage the structure of electrospun PET nanofiber mat, if the suitable temperature was been choosed.

Abstract: Catalysts play a critical role in the synthesis of carbon nanotubes. In this paper, we design a series of experiments to explore the impact of contents of Mo on the products. Analysis show, when the molar ratio of Fe: Mo: Al is 1: 0.2: 16, the carbon nanotubes show the best yields and quality.

Abstract: N-doping nanoTiO2 was prepared by sol-gel method. The TEM,XRD,XPS,BET and UV techniques were used to characterize the crystalline structure.The photocatalytic oxidation effects of SO2 were studied with the fluorescence lamp illumination under the different conditions. The visible light-induced photocatalytic oxidation mechanisms of SO2 were discussed. The results showed that N-doping nanoTiO2 increase the visible-light responsive photocatalytic activity because of the increase of the surface area, O2 lacuna and small particle diameter. There are the optima of the dosage and amount of O2. The removal efficiency of SO2 was greater than 95% under the experimental conditions. The photocatalytic reactions of SO2 included two parts-adsorption and oxidation. The results provide some references for the SO2 control and further application of nanoTiO2.

Abstract: Electroporation through nanochannels has potential as a useful tool for cell transfection. This potential is due to: the low voltage required; the centralized distribution of the potential penetration; the fact that this method causes no harm to the cell membrane, and; the even expression pattern of the target gene after electroporation. Additionally, the stable production process and improved yield rate can reduce the cost of producing the nanochannels and thus make the commercialization of this technique more feasible. This study aims to investigate the relationship between the speed of DNA stretching and the yield rate of nanochannels. We found that when the length of nanochannels is 2 µm, the yield rate can exceed 90% at a stretching speed of 2.3 mm/s . With a similarly high yield rate, longer nanochannels (3 µm) displayed a wider range of stretching speed. We have determined that the stretching speed can influence the adhesion of DNA and the subsequent fabrication of nanochannels. Therefore, this speed must be appropriately controlled.

Abstract: A micro silicon cantilever actuated by ZnO thin film was designed, fabricated and characterized. The ZnO thin film was deposited by RF sputtering at room temperature. The transverse piezoelectric constant d₃₁ was found to be-4.66 pC/N. Time and frequency responses of the cantilever actuator were investigated by means of a laser Doppler vibrometer. The actuator has a sensitivity of 12 nm/V at 15 kHz. Its 1^st bending resonance was observed at 53 kHz. The bandwidth was found to be 27 kHz with damping of 0.35%. The cantilever demonstrated capability of high frequency actuation on a nanometer level.

Abstract: Palladium (Pd) nanoparticles were incorporated into a nylon 6 film via a dry process which consisted of simultaneous vaporization, penetration and reduction processes of palladium (II) bis (acetylacetonate, Pd (acac)₂) at 180°C for various exposure time. The even dispersion of the generated Pd nanoparticles were observed by transmission electron microscope (TEM) and the Pd loading weight of about 15~43 wt% was measured by thermogravimetric analysis (TGA). In order to study the catalytic effect of Pd nanoparticles on the thermal degradation kinetics of nylon 6, TGA data at various heating rates were introduced to Flynn & Wall equation. The thermal degradation activation energy for neat nylon 6 was ca. 162~178 kJ/mol over the thermal degradation fraction of 0.05~0.40 while that of the nylon 6/Pd (26.5 wt%) nanocomposite was ca. 110~169 kJ/mol over the same fraction range. It meant the Pd nanoparticles were acted as a catalyst on the depolymerization of amide group in nylon 6. It was also found that the activation energy decreased slightly with the increasing Pd loading weight.

Abstract: Authors investigated the relationship among processing parameters, microstructures, electrical conductivity and mechanical property of injection molded nanoparticle filled polymer composites at present study. Standard tensile specimens were injected under different injecting pressures and packing pressures. The molded specimens were removing five layers from the surface to observe the microstructures at different positions of the moldings. The electrical properties were measured with a two-terminal standard resistor under DC condition at room temperature, and the mechanical properties of the moldings were measured by INSTRON 5580 Universal testing machine. The results showed that filled nanoparticles may form the best conductive path under the higher packing pressure matched with higher injection pressure. The mechanical properties of the molding depend on not only the concentration of the nanofiller, but processing conditions as well.

Abstract: A zinc oxide (ZnO) nanoparticle gas sensor was formed by spin coating. We annealed the film at 400, 600, and 800°C for 1 h in air to create a gas sensor. The responses of the gas sensor to ethanol under UV light illumination were investigated. We found that the ZnO nanoparticle film annealed at 800°C had the highest sensitivity. This can be attributed to the fact that the defects of ZnO nanoparticle film annealed at 800°C are considerably more than those for the film annealed at other temperatures. This study demonstrates that ZnO nanoparticles have potential applications as room-temperature ethanol sensors.

Abstract: White carbon films with sp¹-hybridization of carbon were synthesized by microwave plasma chemical vapor deposition. The surface morphology of the deposited film, which consisted of nanograins and nanofibers, was observed by scanning electron microscope. The x-ray diffraction peak at 2θ=21.69^o corresponds to the (110) facet of β modifications of white carbon material. The peak position at 283.2 eV in x-ray photoelectron spectrum represents binding energy of C_1s core level of sp¹-hybridization of carbon. Field electron emission properties of the film were tested by using a diode structure in a vacuum chamber. The turn-on field of 2.3V/μm and the emission current density of 360μA/cm² at electric field of 7V/μm were obtained.