Advanced Materials Research Vols. 706-708

Abstract: The purpose of this study was to prepare and characterize tinidazole-loaded poly (lactide-co-ethylene carbonate) (PLEC) microspheres. These biodegradable microspheres were prepared by solvent evaporation method. The effect of selected emulsifier, polymer type, and ratio of tinidazole to PLEC were investigated. An aqueous gelatin solution used as emulsifier resulted in uniform microspheres with spherical surfaces. The PLEC microspheres exhibited rough surface and porous internal structures when compared with the PLA microspheres. The ratio of tinidazole to PLEC (1/10) exhibited higher encapsulation efficiency and drug loading of tinidazole. The introduction of hydrophilic PEC content influenced the structure and encapsulation efficiency of microspheres. These results suggest that the novel PLEC microspheres can be useful for drug delivery systems.

Abstract: A variety of solid acid catalysts especially 12-Tungstophosphoricacid (DTP) supported on silica has been reported for the acylation of anisole, veratrole and toluene. However, the activity of this catalyst is susceptible to coke formation or poor activity. This paper reports the novelties of steam treated SiO₂-DTP core-shell nanoparticles, which exhibits tremendous stability, high activity and enhanced selectivity in the liquid-phase acylation of anisole, veratrole and toluene as compared to conventional DTP supported on silica.

Abstract: Transmission electron microscopy (TEM) can be utilized to identify some specific microstructures of metals and alloys. However, it is very difficult to precisely prepare a TEM specimen from the powder particles with several micrometers. There are more or less drawbacks in conventional preparation method. This paper describes a novel method to prepare specific specimens from the powder particles with several micrometers for TEM study. A TEM specimen approximately 5μm diameter was successfully prepared to electron transparency, which extracted from a 5μm diameter powder particle. The selected-area electron diffraction pattern (SAED) analysis was carried out.

Abstract: With water as the medium, PVP as stabilizer and ammonia as complexing agents and adjusting pH value of the solution, we report an all-aqueous synthesis of highly photoluminescent and stable ZnS quantum dots (QDs) by water-phase synthesis reaction between ZnCl2 and NaS at different temperatures and times. The optimal reaction conditions of PVP-capped ZnS QDs were obtained through experiment as follows: the concentration ZnCl2 and NaS solution both are 1 mM, (PVP):(ZnCl2) = 0.0167 (v/v), (NH3):(ZnCl2)=1:300 (v/v), the optimal reaction temperature is 40 °C, the optimal reaction time is 30 min. With ammonia as complexing agents, Zn(OH)2 can dissolve in ammonia and form to complex ions ((Zn(NH3)4)2+), which make Zn2+ release slowly to control the nucleus growth rate of ZnS, thus obtain small size of nanoparticles. The fluorescence spectra shows that the emission peaks of ZnS QDs around ~395 nm and ~470 nm on the emission spectra, which are consistent with literatures, so nano-ZnS QDs was synthesized successfully in this paper.

Abstract: Press forging forming of thick sheet metal is a combined extrusion process, which is put forward in the presently study. A new technological scheme for a two-step press forging of stepped holes in a thick metal sheet was proposed. Finite element analysis on the two-step process is carried out by using DEFORM-3D. Distributions of effective strain and effective stress were obtained. The study showed that the process not only can form the stepped holes, but also can increase the surface quality and strength of stepped holes in sheet metal parts, According to the numerical simulations process parameter, an experimental die was designed, the simulation results were in good agreement with the experimental data.

Abstract: Based on empirical electron theory of solid and molecule (EET, Empirical Electron Theory of Solids and Molecules) ,this paper calculated the Cr1 – xMxN molecular coating’s valence electron structure of the phase space and the valence electron structure of coating matrix phase out of phase interface. By analysing microscopic valence electron structure, we discussed the alloy elements’ influence on this series of coatings’ resistance. And we found that V elements can significantly increase the metal chromium nitride’s were resistance , element Ti takes the second place, element Al also has some effect.

Abstract: Some trigonal Schiff base amphiphiles with symmetric aromatic cores and different substituted headgroups were designed and their interfacial assemblies were investigated. When on the metal ions subphases, an in situ coordination can occur for all compounds. The coordinated films could be transferred onto solid substrates and subsequently characterized by morphological characterization with atomic force microscopy measurement. Depending on the trigonal molecular structures and different substituted headgroups, these amphiphiles showed distinct assembly behaviors in the organized molecular films.

Abstract: W-type hexagonal ferrite BaZn_0.6Co_1.4Fe₁₆O₂₇ was prepared by the method of coprecipitation with flux. Various products were prepared by different thermal treatments. The microstructure, element composition, crystal structure, phases and dynamic electromagnetic parameters of the products were analyzed by SEM, EDS, XRD and the microwave vector network analyzer. The formation of the ferrite was studied and the optimal thermal treatment condition was confirmed, under which pure tiny W-type hexagonal ferrite powders were achieved.

Abstract: By means of mechanical properties test，the relationship among shear ratio, concentration and electric field, magnetic field, electromagnetic field on the Ni/TiO2/SDBS EMR fluid properties have been analyzed. It had found that with increasing shear ratio，the shear stress of Ni/TiO2/SDBS EMR fluid increased for same composition, but there is a critical value. With increasing concentration，the property of EMR fluid increased for same shear ratio. Coupling electromagnetic field makes the properties improve.

Abstract: Casting defects will always occurred in the cast-steel castings. In order to eliminate the shrinkages more and more risers had been used which increased the final cost sharply. The traditional method was used to the designing process; besides that, the foundry simulation software was introduced to prove the rationality of the technique. The software helps to predict the proper position of the shrinkages. The cooling system was optimized after the analyzed and the final simulation results show the rationality of foundry technique.