Advanced Materials Research Vol. 650

Abstract: A rapid detection of the local anesthetic ropivacaine was measured by electrochemical impedance method. Polypyrrole (Ppy) and polypyrrole (Ppy)-graphene oxide (GO) composites were prepared by electrochemical polymerization on the gold electrode as the working electrode. The electrochemical properties of the Ppy and Ppy-GO composites electrode were characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). Various concentrations from 1 to 20 ppm of ropivacaine were prepared in 0.9% NaCl as the sample solution. Prepared Ppy and Ppy-GO were used as working electrodes, and the sample solution had been measured for a sinusoidal excitation in the frequency range of 100 Hz to 1 MHz. It exhibited the better linearity (R2=0.973) of Ppy/1% GO than Ppy (R2=0.882) from 1 to 20 ppm when the frequency fixed in 100 kHz. All the response and recovery time of 0.1 ppm local anesthetic ropivacaine can be detection in this system within 1 sec, it will be a promising composite material on electrochemical electrode.

Abstract: Organic photodiodes operating in the near-infrared (NIR) region with an operating wavelength of about 850 nm, which corresponds to GaAs-based optical devices, were fabricated by wet process. In the active layer, Copper(II)5,9,14,18,23,27,32,36-octabutoxy-2,3-naphthalocyanine was used as NIR absorption material. A wide-bandgap polymer was doped to decrease the dark current, and an n-type organic semiconductor was doped to increase optical sensitivity. To decrease the dark current further, an electron-blocking layer was added onto the anode. This bi-layer structure was found to be very useful for decreasing the dark current. We also evaluated the on/off ratio, which is very important for application to optical communication devices.

Abstract: Silicon nitride powders high in β-phase content have been prepared by direct nitriding method. The silicon powders were first milled with 30%α-Si₃N₄ and 4% FeCl₃ for 30 minutes. Then the mixture was heat-treated at 1400°C for 2 hours in the pure nitrogen gas. The phase and the microstructure of the as-prepared product were detected by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results showed that the product mainly consisted of β-Si₃N₄, whose content is more than 92%, and a little amount of α-Si₃N₄, and no silicon were detected within the detection limit.

Abstract: A novel scheme is proposed to achieve beam focus by applying the method of embedded coordinate transformation[1] in this paper. The focus degree of electromagnetic waves is determined by the structure parameters in the transformation region. Theoretical analysis and simulating results are given to demonstrate that our design is feasible and practical, and might have some potential applications in solar cell plate. Moreover, full-wave numerical simulations do further work to confirm the theoretical analysis.

Abstract: Chemically bonded solid phase materials are very important in separation chemistry. The chemically modified silica gel contains rest silanol groups that can affect the retention properties when they are used for separation of compounds. Some commercially available solid phase extraction (SPE) materials based on silica gel were analysed for rest silanol groups by near infrared spectroscopy. The combination frequency of the water molecules in the 5500- 5000 cm ^-1 region was used in identifying the nature of water molecules on the surface and the information was used to identify the types of silanol groups on the surface. Second derivative technique was employed in the detailed analysis. Nine different SPE materials including C18, C8, C₆H₅, NH₂, OH, CN, SiOH, SA (SCX) and SB (SAX) were examined by near infrared spectroscopy for rest silanol groups. The results show that the non-polar and polar stationary phases contain vicinal silanol groups and the ion exchange solid phase materials contain free, vicinal and geminal silanol groups.

Abstract: Hydrogen-charging with various current densities was used to introduce hydrogen into X80 pipeline steel. The permeability (J_∞L), the apparent diffusivity (D_app) and the solubility of hydrogen (C_app)in X80 pipeline steels which were calculated by electrochemical hydrogen permeation curves were compared with those obtained from that of X80 pipeline steels in H₂S saturated environment. Results show that in 0.5 mol/L H₂SO₄ + 3.1×10^-3 mol/L Na₄P₂O₇ (hydrogen evolution poison) solution, when hydrogen-charging current density is 30 mA/cm², the kinetic parameters of hydrogen permeation of X80 pipeline steels agree with that of H₂S saturated environment well. Another two heat-treatment specimens of X80 pipeline steel furthermore verified the reliability of the simulating results.

Abstract: The preparation of melt-blown filtration materials was studied in this paper. The effects of collection distance, screw speed, air temperature on web structure and properties were discussed, and moreover, fiber diameter, thickness, surface density, pore size, air permeability and breaking force of PP nonwoven fabrics were characterized in this paper.

Abstract: Carbon dioxide reforming of methane (CDR) can convert two greenhouse gases, methane can carbon dioxide, into useful syngas. Nickel-based catalysts have been extensively investigated due to their high activity and low cost. However, coke formation over Ni catalyst is serious and leads to rapid deactivation of the catalyst. Coke resistant Ni catalyst for CDR reaction is desired. In this paper, recent progresses in the design and preparation of coke resistant Ni catalysts supported on solid solutions, zeolite, perovskites and perovskite type oxides, hexaaluminates or substituted hexaaluminates, pyrochlore, montmorillonites, and hydrotalcites for CDR were summarized. The progresses in the use of promoters, in the effect of supporting materials and in the preparation methods have been discussed. The future development of coke resistant Ni catalysts for these processes is briefly addressed.

Abstract: A coupled numerical simulation between thermal-mechanical and microstructure evolution was realized through embedding the developed user subroutines into the FEM software DEFORM-3D system. Then the dynamic recrystallization fraction and average grain size of In718 alloy in cylindrical cup backward extrusion with different parameters was solved and analyzed. The complete dynamic recrystallization occurs in the middle of cylinder wall and the grain size is the finest. However, the grain size of top of cylinder wall changes less because of the less plastic deformation. Furthermore, higher speed of punch is useful to the DRX but it is not enough time to occur dynamic recrystallization completely with much higher speed of punch. In spite of more recrystallization occurring in the bottom, the grains grow in the cylinder wall so that much higher temperature goes against improving finer and uniform of grain size. Therefore, it is better for obtaining finer and uniform grain size with 1000(°C)-1050(°C) and 5(mm/s) in In718 alloy cylindrical cup backward extrusion according to the research.

Abstract: In this study, we present the first electrochemical investigation on the electrochromic property of poly (4-aminoazobenzene) coating prepared by oxidative coupling polymerization. A UV-vis spectrum was used to monitor the photoisomerization process of the polymer. At the same time, the electrochemical activity of the polymer was explored by cyclic voltammogram (CV) measurement, showing that the intrinsic electroactivity of the aniline structure was maintained in the polymer. Moreover, the electrochromic performance of the polymer was investigated by measuring electrochromic photographs and UV absorption spectra.