Effects of ultrasonic dispersion on structure of electrodeposited Ni coating on AZ91D magnesium alloy

To obtain the refined electrodeposited nickel layer on AZ91D magnesium alloy,ultrasonic technology was applied in the processes of pre-treatment and electrodeposition.The phases of pre-treatment layer and the nickel coating were analyzed by X-ray diffractometry(XRD)and X-ray photoelectron spectroscopy(XPS),and the microstructure was observed by scanning electron microscopy(SEM).Then,the effects of ultrasonic dispersion on the microstructure of pre-treatment layer and the grain refinement of electrodeposited nickel layer were discussed.The results showed that the pre-treatment electrodeposited Cu-Sn layer with compact microstructure could be synthesized in alkaline copper-tin liquid with ultrasonic agitation,as a result,smooth and refined nickel coating formed on AZ91D magnesium alloy.On the other hand,preferred orientation in the coating decreased because of the refined grains.

Synthesis and Characterization of Suspension Polymerized Styrene-Divinylbenzene Porous Microsphere Using as Slow-Release-Active Carrier

Functional porous microspheres used for the slow release carrier of actives in cosmetics or pharmaceuticals were prepared by modified suspension polymerization of styrene （ST） with divinylbenzene （DVB） in the presence of toluene, cyclohexanol and heptane as porogenic diluents. The use of ultrasonic dispersion decreases the beads＇ size and improves the uniformity. The effects of the porogen mixture, DVB content and solvent extraction on the surface performance of the synthesized beads were studied. The microspheres were characterized by scanning electron microscopy （SEM） and BET surface area determination. It was found that a great proportion of the non-solvating porogen increases the pore diameter and the specific surface area. High DVB concentration also results in the great specific surface area and porosity. When the ratio of toluene/cyclohexanol is 1：2, DVB content is at the range of 40%-60% and methylene chloride was used as extractant, the beads with good spherical shape and pore size were obtained. The prepared porous microspheres were applied as active carriers and showed satisfactory slow release effect. Over 10h constantly sustained release was observed in vitro releasing test for hydroquinone-loaded microspheres. Great surface area promoted high concentration of released hydroquinone.

Beta-Cyclodextrin as Carbon Source for Synthesis of LiFePO_4/C with Improved Electrochemical Properties in Lithium-ion Batteries

For beta-cyclodextrin (β-CD) may form complexes with metal ions during ballmilling process, it was used as a novel carbon source to synthesize LiFePO_4/C cathode composite in lithium-ion batteries via solid-state reaction. This composite should has fine particle size and good electrochemical performances. The powders were characterized by XRD, SEM, TEM and galvanostatic charge-discharge. Compared with bare LiFePO_4 and LiFePO_4/C composite with glucose as carbon source by the same procedure and nearly the same content of carbon in the final cathode, the LiFePO_4/C composite with beta-cyclodextrin as carbon source shows much higher discharge specific capacity and more excellent rate performance. Ultrasonic dispersion between ballmilling and sinter process for 2 h was appropriate and useful for final LiFePO_4/C to reach higher discharge capacity. The SEI experiment was carried out to explore the effect of beta-cyclodextrin on the cathode materials, and the results indicate that coating with beta-cyclodextrin can improve the electrochemical performance of LiFePO_4 by decreasing the resistance of charge transfer (R_ ct) and improving the chemical diffusion coefficient (D_ Li).

A new procedure to enols of 2-acylmethyl-4,4-dimethyl-2-oxazolines underultrasonically dispersed potassium system

Various enols of 2-acylmethyl-4, 4-dimethyl-2-oxazolines were prepared in moderate yields via ultrasonically catalyzed reactions of 2, 4, 4-trimethyl-2-oxazoline with arenecarboxylic esters in the presence of UDP-t-BuCl-i-Pr2NH system.