Abstract: Co-immobilize enzyme by cross-linking and embedding, optimize conditions for immobilizing, determinate the enzymatic properties of co-immobilized enzyme and study the methods for preparation of genipin using co-immobilized enzyme to hydrolyze geniposide. Optimized immobilizing conditions include glutaraldehyde concentration being 0.15%, cross-linking temperature being 20°C, cross-linking time being 2 hours, the activity of co-immobilized β-glucosidase and cell reaches to 65.33U/mg and the enzyme activity recovery being 52.63%. Enzymatic properties of co-immobilized enzyme are following: optimum temperature is 55°C and optimum pH is 5.0. The transformation experiments are carried out with co-immobilized enzyme. The results show that half-life of co-immobilized enzyme reaches around 40 days, higher than the normal immobilized enzyme. The conversion rate of geniposide is above 95% after 8 hours. The genipin is isolated, purified and recrystallized to reach more than 98% of purity by High Performance Liquid Chromatography. Advantages to prepare genipin using co-immobilized enzyme include low cost, high yield, environmental friendly and easy to manufacturing.
Abstract: Eu2O3 nanoparticles were fabricated by thermal decomposition of europium propionate crystals, which can be facilely obtained via crystallization. The decomposition and morphlogy of the crystallized product were characterized by X-ray diffractionmetry (XRD), simultaneous differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) as well as scanning electron microscopy (SEM). The effects of the calcination temperature on the resultant microstructures such as crystallinity, particle size and particle dispersibility were investigated by XRD and transmission electron microscopy (TEM). The results indicated the morphology of the as-calcined products shows transmissibility compared with the precursor and that the calcination temperature of europium propionate is crucial to evolution of the resultant morphology from three-dimensional network of agglomerated nanoparticles to dispersed nanoparticles.
Abstract: The mechanism and method were deduced on surface modification of nano-ZnO by titanate coupling agent. EVADPE/ZnO nanocomposite material was prepared, and the tensile strength was tested. Three relatively optimal groups of process parameters were obtained by orthogonal experiment, BP-GA model and BP-PSO model respectively, in which the parameter obtained through BP-GA model was equal to that obtained through BP-PSO model. The iterative times of BP-PSO algorithm were smaller than that of BP-PSO algorithm. With analysis, it was showed that the group of process parameters obtained by BP-GA model and BP-PSO model based on the orthogonal experiment data were much better than that group obtained by orthogonal experiment. The optimal velocity of BP-PSO algorithm was faster than that of BP-PSO model.
Abstract: This work suggested the growth of SiC and SiO2 nanostructures from heating of rice husk ash and carbon-metal assisted. The rice husk was boiled in 1 M hydrochloric acid solution with temperature of around 90 °C for 1 hour, and then washed in distilled water and dried under the sun. The dried acid-treated rice husk was burned in the furnace with normal air for 1 hour, then high purity SiO2 was produced. The high silica ash mixed with Cu or SnO2 powder and coconut shell charcoal were grounded for mixtures powder. The mixtures powder and Si substrates were placed on the alumina boat and put in the middle of furnace. The furnace was heated at high temperature under atmosphere of argon gas. The heated products and Si substrates were studied by X-rays diffraction and scanning electron microscope. The SiC and SiO2 nanostructures were observed.
Abstract: We investigate the use of ellipse refractive index structure to enlarge photonic band-gap (PBG). The PBG structure was prepared on porous silicon with 10 unit cell. Each unit cell is consisting of 21 layers with the refractive index varying according to the envelope of the ellipse function. The width of this photonic band-gap is high to 451nm.
Abstract: Monodisperse α-Fe2O3 nanoparticles with average particle size of 110 nm were successfully prepared using olyvinylpyrrolidone (PVP) as surfactant via a novel hydrothermal route. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM). The experiments results revealed that PVP and the concentration of NH4HCO3 have played a crucial role in the formation of the monodisperse a-Fe2O3 nanoparticles.
Abstract: Vitamin A Palmitate-loaded Nanostructured Lipid Carriers were prepared by High Pressure Homogenization (HPH) technique. The influences of storage conditions such as time and temperature on the physical and chemical storage stability of VAP-NLCs were studied in details. Preparation and physicochemical properties of VAP lipid nanoparticles were investigated using various analytical equipments such as TEM, photon correlation spectroscopy (PCS), laser diffractometry (LD) and ultraviolet spectrophotometer. The respective optimal HPH pressure and cycles were 70MPa and 5 cycles, so VAP-NLC dispersions under the optimized condition gave rise to the entrapment efficiency (EE) of 99.8%, PI of 0.234, mean diameter of 144±1.7 nm (2% VAP loading capacity). In addition, VAP lipid nanoparticle has a distinct spherical shape, its particle sizes were around 60–330 nm according to VAP contents and zeta potential values -18~-23 mV. Furthermore, the pH of VAP-NLC dispersion was near to 7.0. This study showed that VAP-NLC could hopefully be applied for food products.
Abstract: The thesis selected nano-titanium dioxide compound silver antibacterial and thulium compound nanometer antibacterial as research object, whose application are the widest. Their characters to resist staphylococcus aureus, colon bacillus and Candida albicans were studied by qualitative analysis, quantitative analysis and TEM. The study indicated that nano-titanium dioxide compound silver antibacterial is dissolving antibacterial and thulium compound nanometer antibacterial is non-dissolving antibacterial. These two kinds of antimicrobials both have a minimal inhibitory concentration of the three kinds of bacteria. Different nano-antimicrobials act on bacteria, the changes of bacteria’s shape are different, and this indicates the mechanism of action is different.
Abstract: The influences of space velocity, temperature and copper content in Cu-MCM41 catalysts with high copper content up to 26.1wt.% on the catalytic activity in NO reduction by CO were investigated. Results indicated 1) the prepared materials exhibited excellent activity for NO+CO reaction, 2) the catalytic activities increased with the copper contents and NO can be fully converted to N2 for the catalyst containing 26.1wt.% Cu with the space velocity of 30,000ml•g-1•h-1 at 673K to 823K, 3) catalytic activities of the original catalysts with the temperature were volcano-type curves, however, it increased straightly with temperature over the catalysts after reacting at 723K for 1h, which might be attributed to the different active sites and different catalytic mechanisms of the catalysts at lower and higher temperature, 4) the catalytic activity did not decline after reacting at 723K for 20 h in a reactant gas mixture of 33,000 ppm NO and 66,000 ppm CO.
Abstract: In order to improve the dispersion of multi-walled carbon nanotubes (MWCNTs), MWCNTs were physically modified by the surfactant of Poly (vinyl pyrrolidone) (PVP), cetyl trimethylammonium bromide (CTAB) and sodium dodecylbenzene sulfonate (SDBS), and were chemically treated by the acid oxidation. Measuring the zeta potential of the dispersions of modified MWCNTs and surface contact angle of modified MWCNT powders, influence of acting forces on the dispersions of modified MWCNTs was analyzed. The balance of electrostatic repulsion and van der Waals forces determines the stabilization of aqueous modified MWCNT dispersions. The sufficient reactive groups, ions and long molecular chains play important roles for such balance.