Applied Mechanics and Materials Vols. 395-396

Abstract: The application of nanocapsules in pharmaceutical, cosmetic and food industries has attracted great attention from scientific research. In the food field, nanocapsules of aroma, bioactive components have been gradually widely used in food additives, beverage and nutrition and nutraceuticals, owing to their excellent sustained-release, stability and resistance to oxidation. This concise review focus on several kinds of nanocapsulation techniques, such as emulsion technique, emulsification-solvent evaporation technique, complex coacervation, inclusion complexation, supercritical fluid technique, solvent diaplacement for food ingredients, and then forwards the further development of the nanocapsulation techniques in the food industry.

Abstract: The nanoMgO and active nanoSiO₂ were prepared by the special liquid-phase precipitation method. Subsequently, Chrysotile nanotube was prepared of by hydrothermal method using the nanoMgO and active nanoSiO₂ as precursors at 220°C under 23atm in basic solution. The surface topographies and composition of the Chrysotile nanotube were characterized by XRD and TEM. Then, the dispersive property of particles modified by oleic acid was analyzed by IR. The tribological properties) were explored by adding the modified nanomagnesium silicate hydroxide to 2^# lithic-grease after dispersing uniformly. Compared with the blank sample, it can significantly reduce the friction traces of the metal surface, improve extreme pressure performance. The friction coefficient is still stable when the temperature is raised during the friction. Nanotube power can be adhered and spread on the worn metal surface. Thus self-repairing coating forms on the worn surface.

Abstract: A layer of densely distributed copper particles has been deposited on the surface of multi-walled carbon nanotubes (MWCNTs) by pretreatment including oxidation, sensitization and activation and electroless plating methods. Due to our experiments, the rate of deposition will increase by increasing the PH value and temperature of the solution bath properly. Different morphologies of coatings have been obtained with different PH values and temperatures. The most suitable PH value and temperature of the plating bath were 11.5 and 20°C, respectively.

Abstract: Silver Nanoparticles has been prepared using the complex of carboxymethyl cellulose (CMC) and Polyvinylpyrrolidone (PVP) as a template and used as SERS substrate. The effect of the ratio of CMC to PVP on silver nanoparticles was discussed. Silver Nanoparticles were characterized by UV-visible spectroscopy, transmission electron microscopy and Raman spectroscopy. The results show that the ratio of CMC to PVP plays a crucial role in the performance of nanoparticles. TEM studies reveal that particles are mostly near-spherical in shape with an average size of 60-70 nm. The SERS enhancement of these silver nanoparticles was tested by using Rhodamine 6G (R6G) as a probe molecule. The silver nanoparticles prepared with the complex of CMC and PVP as a template have been shown to provide strong enhancements in the SERS spectrum of R6G. Keywords: Carboxymethyl cellulose; Polyvinylpyrrolidone; Surface-enhanced Raman scattering; silver; Template

Abstract: Monte Carlo simulation method of microstructure evolution in nanocomposite ceramic tool materials is set up. Two-phased material systems with the same area fractions but various sizes of nanoparticles are designed, and the processes of microstructure evolution are simulated. The influences of nanoparticle size on microstructure and grain growth are observed and discussed quantitatively. It is found that the mean size of matrix grains increases with the increase of nanophase size during simulation, and intragranular-type microstructure is more difficult to form. The material Al₂O₃/nanoSiC is developed and the simulated results are verified.

Abstract: N-doped meso/macroporous carbon materials were synthesized by using melamine-formaldehyde resin as carbon precursor and silica spheres as a removable template. Scanning electron microscopy images reveal that the macropores of carbon materials can be modulated by changing the diameter of template. While the BET results verify that the template had no obvious effect to the mesopores of the materials. The as-synthesized carbon materials with a bimodal pores structure display a high surface nitrogen content of 30wt%. XPS analysis reveals that N atoms are mostly bound to the graphitic network in two forms, i.e. pyridinic and pyrrolic nitrogen.

Abstract: ZnO nanorod arrays were successfully prepared by chemical bath deposition (CBD) and hydrothermal method (HTM), respectively. The photovoltaic performance of ZnO nanoarrays as photoelectrodes in dye-sensitized solar cells (DSCs) was investigated. Experimental results show that ZnO seed crystals prepared by a sol-gol process have c axis orientation and consist of nanoparticles within the range of 50~100nm. The same particle size and orientation is well preserved in ZnO nanoarrays grown on the seed crystal layers. The photovoltaic performance of DSCs based on ZnO nanoarrays as the photoelectrodes is poor, due to the weaker adsorption bond force between ZnO and dye, and lower dye adsorption quantity. By contrast, the DSCs composed of ZnO arrays prepared by hydrothermal method have optimal performance, the corresponding short circuit photocurrent density (J_sc), open circuit voltage (V_oc), fill factor (FF) and photoelectric conversion efficiency (η) are 4.89 mA/cm², 0.650V, 0.39 and 1.25 %, respectively.

Abstract: Ni-ZrO₂-CeO₂ nanocomposite coatings were prepared by pulse electrodeposition. The effect additions of ZrO₂ and CeO₂ nanoparticles, average current density, duty ratio and frequency of pulse current on nanoparticle contents of Ni-ZrO₂-CeO₂ nanocomposites were studied. The surface morphologies and microhardness of different nanocomposite coatings (Ni-ZrO₂, Ni-CeO₂, Ni-ZrO₂-CeO₂) were analyzed. The results show that, with the average current density, duty ratio and frequency increased, the nanoparticle contents increased at first and then decreased. Compared with Ni-ZrO₂ and Ni-CeO₂, the surface morphology of Ni-ZrO₂-CeO₂ nanocomposite coating showed better smooth surface and more compact microstructure, the microhardness was also higher.

Abstract: For nanopore drilling in a membrane by transmission electron microscope, a straight through-pore is in general not the case of the fabrication result. For instance, a silicon nitride nanopore with an hourglass profile and a silicon oxide nanopore with a pyramid cross-section were reported in recent researches. The reason for not getting a straight through-pore by the electron drilling was analyzed. A hypothesis, which improving heat conduction property of the membrane would lead to a straight nanopore drilling, was proposed. And the hypothesis was confirmed true.

Abstract: Barite-fluorite metallogenic belt of southeast Sichuan is one of the important metallogenic belt in China. The initial ratio of ⁸⁷Sr/⁸⁶Sr is the good tracer in study of diagenetic mineralization process and sources of ore-forming materials. The ⁸⁷Sr/⁸⁶Sr ratio of fluorite and barite from barite-fluorite deposits in southeast Sichuan is 0.708800~0.712999, and it similar to The ⁸⁷Sr/⁸⁶Sr ratio of Cambrian carbonate rocks and ordovician limestone, but expect the lower Cambrian Niutitang group stratum, the Ba content of other layers are generally low, Therefore, the Ca source of ore-forming materials should be multisource, mainly from Cambrian-Ordovician carbonate strata , and the main Ba source of layer should be the lower Cambrian Niutitang group stratum.