Search

To find suitable biodegradable materials for implant applications, Mg−6Zn−0.3Mn−xCa (x=0, 0.2 and 0.5, wt.%) alloys were prepared by semi-continuous casting followed by hot-extrusion technique. The microstructure and mechanical properties of Mg−6Zn−0.3Mn−xCa alloys were investigated using the optical microscope, scanning electron microscope and tensile testing. Results indicated that minor Ca addition can slightly refine grains of the extruded Mg−6Zn−0.3Mn alloy and improve its strength. When 0.2 wt.% and 0.5 wt.% Ca were added, the grain sizes of the as-extruded alloys were refined from 4.8 to 4.6 and 4.2 μm, respectively. Of the three alloys studied, the alloy with 0.5 wt.% Ca exhibits better combined mechanical properties with the ultimate tensile strength and elongation of 334 MPa and 20.3%. The corrosion behaviour, cell viability and antibacterial activities of alloys studied were also evaluated. Increasing Ca content deteriorates the corrosion resistance of alloys due to the increase of amount of effective cathodic sites caused by the formation of more Ca2Mg6Zn3 phases. Cytotoxicity evaluation with L929 cells shows higher cell viability of the Mg−6Zn−0.3Mn−0.5Ca alloy compared to Mg−6Zn−0.3Mn and Mg−6Zn−0.3Mn− 0.2Ca alloys. The antibacterial activity against Staphylococcus aureus is enhanced with increasing the Ca content due to its physicochemical and biological performance in bone repairing process.

Chilo suppressalis Walker (Lepidoptera: Crambidae) is one of the most destructive pests occurring in the rice-growing regions of Asia. Parasitoids, mainly egg parasitoids, have been of interest for several years even with practical used cases. Therefore, the potential impact of insecticides on natural enemies needs great attention. In this study, chlorantraniliprole was evaluated for its impact on C. suppressalis and two dominant parasitic wasps. Bioassays showed that chlorantraniliprole had negligible toxicity to Eriborus terebrans but was significantly toxic to Chelonus munakatae; the mortality exceeded 50% when the concentration reached 46.83 ng/cm

Based on the density functional theory method, the ab initio calculation with GGA+U was performed to investigate the electronic structure and properties of W-doped TiO 2 . The results indicated that W-doping induced ferromagnetism and shifted the absorption spectra to visible light region. The ferromagnetism derived from the spin-split of O 2p and W 5d caused by p–d orbit hybridization. Several impurity bands under the conduction band decreased the band gap. The experiment results illustrated that the ferromagnetism had occurred and the absorption spectra had a shift to visible light region in W-doped TiO 2 samples. The experiment results are consistent with the calculation ones.

boron carbide–cerium boride porous composites are prepared by hot pressed sintering, and mechanical properties and microstructure of boron carbide–cerium boride porous composites were tested. The results show that Flexibility strength of B4C-CeB6 porous composites is greatly improved compared with that of monolithic porous boron carbide. B4C react with CeO2 to completely form CeB6 in porous composites. CeB6 particles in B4C grain boundary are produced by in-situ reaction. The presence of CeB6 reinforcing particles could also suppress growth of B4C grains which normally leads to improved strength.

B4C-CeB6 porous composites are prepared by hot pressed sintering between 1900°C and 2000°C, and mechanical properties and phase composition of B4C-CeB6 porous composites were tested. The results show that the porous rate of B4C-CeB6 porous composites ranges between 30%-48% at sintering temperate 1900°C-2000°C. Porous rate of B4C-CeB6 porous composites is decreased with temperature be increased. Flexibility strength of B4C-CeB6 porous composites is greatly improved compared with that of monolithic porous boron carbide. B4C react with CeO2 to completely form CeB6 in porous composites.

Based on the density functional theory method, the ab initio calculation with GGA+U was performed to investigate the electronic structure and properties of W-doped TiO2. The results indicated that W-doping induced ferromagnetism and shifted the absorption spectra to visible light region. The ferromagnetism derived from the spin-split of O 2p and W 5d caused by p–d orbit hybridization. Several impurity bands under the conduction band decreased the band gap.

o make full use of magnesium slags, the C2AS-CAS2 composite pavement bricks were sintered by using magnesium slags, kaolin and Al2O3 at normal pressure. The phases, microscopy, size deviation, compressive strength and anti-hydration property of samples were analyzed using XRD, FE-SEM, EDS, mechanical testing and others techniques. The results show that the main phases of the samples are C2AS and CAS2; the transverse contraction is 3.5%, while the longitudinal shrinkage is 4.2%; the compressive strength is up to 65.3Mpa; the samples have well anti-hydration property. The C2AS-CAS2 composite pavement bricks have excellent properties.

The thermal shock and hydration resistance property of the light heat-insulation refractory materials is studied, which were prepared using high calcium magnesia slag as main raw materials. The phases and microscopy were characterized by means of X-Ray diffraction (XRD), field emission scanning electron microscope (FE-SEM). The results show that the main crystalline phase is CAS2, and it is with low volume density, excellent thermal shock and hydration resistance property.

For the purpose of obtaining the high-efficiency TiO2 photocatalyst carrier, the mechanism and influences of different substrates on photocatalytic activities of TiO2 membranes were investigated. Three kinds of membranes TiO2/Al2O3/Al, TiO2/Al and TiO2/glass were prepared using the dip-coating method. Methyl orange solution with pH=3 and initial concentration 20 mg/L was degraded under the UV irradiated for 2 h with three membranes. The discoloring ratios are 74.7%, 59.1%, 52.6% respectively after 1h, and become above 96% after 2 h. It indicates that Al and Al2O3/Al as carriers are able to enhance photocatalytic activities to some extent, while glass just as carrier that have no influence.

CAS2-Al2O3 (Anorthite-alumina) refractory materials were prepared with magnesium slag, kaolin from Shanxi province of China and alumina as raw materials. The effects of sintering temperature, holding time and the rate of heating on the microscopic structures were investigated. The results showed that the sintering temperature and holding time are more important to CAS2-Al2O3 refractory materials than the rate of heating in a certain extent. According to XRD and SEM analysis results, it indicates that CAS2 and Al2O3 are the main phases which occurs in the temperature ranges of 1350-1400°C. The higher the sintering temperature is, the greater the grains grow. At the same time, while the temperature rising, it tends to precipitate the alumina particles. It is appropriate to keep 2h in 4°C/min heating rate at sintering temperature. CAS2-Al2O3 refractory materials have porous mesh structure.

The hydration resistance of gehlenite-forsterite refractory material has been studied. The results show that the sample hydrated for 72h have no obvious cracks or deformation and gets a maximum weight increasing ratio of 0.073%. It suggests that it has excellent hydration resistance property. Before being hydrated, the main phases are C2AS and M2S; after being hydrated for 72h, the main phases is not changed, while the diffraction peaks slightly shift to left. With the increase of the hydration time, surface morphology change greatly. During the course of hydration, firstly, the surface attachments are sheded from the surface, the matrix is exposed; secondly, the stick big grains are generated; thirdly, the mesh grains are formed; finally, hydration products fell off or dissolved, and a new course starts.